Prevalence and determinants of Non-Nutritive Sucking on ...

Prevalence and determinants of Non-

Nutritive Sucking on Anterior Open

Bite in Children Attending Primary

School

Liyana Tanny

A dissertation submitted in requirements for the research degree

Masters of Philosophy (Honours)

Faculty of Science

School of Dentistry and Health Sciences

Charles Sturt University

Wagga Wagga

Australia

January 2020

II

STATEMENT OF AUTHENTICITY

I, Liyana Tanny, hereby declare that this submission is my own work and that, to

the best of my knowledge and belief, it contains no material previously published

or written by another person nor material which to a substantial extent has been

accepted for the award of any other degree or diploma at Charles Sturt University

or any other educational institution, except where due acknowledgement is made

in the dissertation. Any contributions made to the research by colleagues with

whom I have worked at Charles Sturt University or elsewhere during my

candidature is fully acknowledged.

I agree that the dissertation be accessible for the purpose of study and research

in accordance with the normal conditions established by the University Librarian

for the care, loan and reproduction of the thesis.

07/01/2020

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Signature Date

III

ACKNOWLEDGMENTS

I would like to first and foremost thank the supreme power the Almighty God

(Allah) who has guided me throughout my academic life and immersed me with

blessings which allowed me to be where I am today.

I want to take this opportunity to express my sincere gratitude to my supervisors

who have guided and mentored me throughout this journey, without their valuable

input and complete support, this would not have been possible. Dr Boyen Huang

for his initial support in commencing this project and his valuable ideas and

concepts for making this project a reality. Dr Geoff Currie for his ongoing and

unfailing support when times get rough and his exceptional input into the

statistical analysis of this project. Dr Ashraf Shaweesh, for his valuable and

knowledgeable input on the content of this dissertation.

I am extremely grateful to my parents (Mustafa & Nariman) for their unconditional

love and ongoing support. Their limitless care and sacrifice in educating me and

preparing me for my future has been tremendous. I want to thank my parents-in-

law (Hazim & Maiwaa) for their continuous support throughout this journey.

I want to express my deepest gratitude to my loving husband and soulmate,

Ahmed Al-Humairi. The holistic support he provided me with is exceptional and

everlasting, and without him this would not be a reality. Lastly, I would like to

thank my beautiful children, Miral and Hamza who have been a big part of this

journey.

IV

ABSTRACT

Introduction

Anterior open bite (AOB) is a malocclusion that is depicted by lack of contact

between the anterior teeth when the jaw is in maximum closure. It is one of the

most complex malocclusions to treat and manage and it has been proven to affect

speech, mastication and aesthetic appearance of the face. Aetiological factors of

anterior open bite include unfavourable growth capacity and heredity, enlarged

anatomic structures such as the tongue, tonsils or adenoids and environmental

factors involving non-nutritive sucking (thumb/pacifier). The reported prevalence

suggests that there is inconsistency in the extent of occurrence frequency of this

occlusion as well as aetiological factors associated. The aim of this current study

was to investigate the prevalence of non-nutritive sucking habits and

determinants of AOB in Australian children aged seven to 12 years.

Methods

A cross-sectional study was carried out involving 208 primary school children in

the regional town of Orange, New South Wales, Australia. A questionnaire

addressing sociodemographic data, medical conditions known to be associated

with malocclusion, data of nutritive and non-nutritive sucking habits, and

illustrations of different malocclusions to be selected for the child was

administered to parents/guardians of children enrolled in primary schools in

Orange New South Wales. Data analysis involved descriptive statistics,

inferential, multivariate and neural analysis. Chi square tests (p <0.05) and odds

ratio calculations were used for inter-variable comparisons. The impact of non-

nutritive sucking and duration of non-nutritive sucking on anterior open bite were

analysed using neural analysis.

V

Results

According to the information provided by the parents, the prevalence of AOB was

24.1% and of those AOB cases, 76% reported to have carried out thumb-sucking

habits. No statistical significance was noted between the type of malocclusion

and child’s aged at presentation (P=0.1786), the child’s gender (P=0.918) or

whether the child had orthodontic intervention (P=0.1217). Of the children who

commenced thumb-sucking at age two to five years, 100% had developed an

AOB. No child with a duration of six months or less of thumb-sucking had

developed AOB. Children who were bottle-fed were 1.9 times more likely to

develop AOB than breastfed children. Children whose parents had lower levels

of education were three times more likely to develop an abnormal bite. Neural

analysis confirmed that both thumb-sucking and duration of thumb-sucking

presented the highest association with anterior open bite.

Conclusions

Socioeconomic factors and sleeping issues were linked to malocclusions. A

significant relationship between abnormal bite and the need for tonsillectomy

and/or adenoidectomy surgery was identified. Thumb-sucking and duration of

thumb-sucking represented the strongest predisposing factors for anterior open

bite. Breastfeeding provided a protective effect against the development of an

abnormal bite, and conversely, bottle-fed children were more likely to develop an

abnormal bite. Longer duration of breastfeeding and cessation of non-nutritive

sucking habits, particularly thumb-sucking needs to be encouraged.

VI

TABLE OF CONTENTS

Statement of Authenticity II

Acknowledgements III

ABSTRACT IV

List of Figures IX

List of Tables X

List of Abbreviations and Acronyms XI

1 BACKGROUND 1

1.1 Introduction 2

1.2 Dental Occlusion 4

1.2.1 Definitions and Classifications 5

1.2.2 Structures Involved in Occlusion Development 9

1.2.3 Development of Dental Occlusion 10

1.3 Malocclusion 14

1.3.1 Anterior Open Bite (AOB) 14

1.3.1.1 Prevalence of AOB 17

1.3.1.2 Development of AOB 20

1.3.1.3 Aetiology of AOB 21

1.3.1.3.1 Skeletal 22

1.3.1.3.2 Oral Habits 23

1.3.1.3.3 Other Aetiological Factors 24

1.3.1.4 Treatment of AOB 24

1.3.2 Other Malocclusions 27

1.4 Factors Affecting Malocclusion 29

2 LITERATURE REVIEW 31

2.1 Open Bite Malocclusion 32

2.1.1 Prevalence of AOB 34

2.1.2 Prevalence of Non-Nutritive Sucking Habits 35

2.1.3 Correlations of AOB and Determinant Factors 37

2.1.4 Treatment Options 39

2.1.5 Burdens of AOB on the Community 43

2.2 State of the Problem 44

VII

3 METHODS 46

3.1 Research Question 47

3.2 Aims and Objectives 47

3.3 Study Variables 47

3.4 Overview of Method 47

3.5 Data Collection 48

3.6 Selection Criteria 50

3.7 Statistical Analysis 52

3.8 Ethical Considerations 53

4 RESULTS 54

4.1 Descriptive Analysis 55

4.2 Inferential Analysis 59

4.3 Multi-Variate Analysis 62

4.4 Neural Analysis 65

4.4.1 Combined Deep Bite and Open Bite 65

4.4.2 Open Bite Only 68

4.4.2.1 Method 69

4.4.2.2 Results 71

5 DISCUSSION 73

5.1 Demographics 75

5.2 Questionnaire 78

5.3 Prevalence 80

5.4 Non-Nutritive Sucking 84

5.5 Feeding Modalities 86

5.6 Sleeping Issues 89

5.7 Limitations 90

5.8 Recommendations 92

5.9 Conclusions 93

REFERENCES 95

APPENDICES 111

VIII

LIST OF FIGURES

1.1 An illustration of facial and intra-oral photographs displaying the features of a patient with AOB (Kim & Sung, 2018, p. 284).

2

1.2 An illustration of the temporomandibular joint showing the difference in mandibular position between a CO (solid line) and CR (broken line) (Shildkraut, Wood, & Hunter, 1994, p. 336).

7

1.3 Functional anatomy of the temporomandibular joint illustrating the position of the mandible to the maxilla with the intra-articular disc is in place (Helland, 1980, p. 147).

8

1.4 Representation of occlusion development of the first molar with illustration of the terminal plane at approximately 5 years of age, and initial contact at approximately 6.5 years and final occlusion at about 12 years (Moyers, 1973, p. 135-137).

11

1.5 Representation of an open-bite pattern using a cephalometric tracing of landmarks and planes (Cangialosi, 1984, p. 30).

16

1.6 This diagnostic flow chart demonstrates the possibilities and relationships between skeletal and dental relationships in open bite malocclusion (Ngan & Henry, 1997, p. 91-98).

17

2.1 Comparison between ideal class I anterior occlusion (A) and anterior open bite malocclusion (B) (Ackerman & Proffit, 1969, p. 445).

33

2.2 An illustration of AFH: Anterior facial height, and PFH: Posterior facial height, the objective of treatment is to maintain AFH and to improve PFH (Horn, 1992, p. 181).

33

2.3 Maxillary palatal crib. The extensive dimension vertically allows ample incorporation of the open-bite region (Torres et al., 2006, p. 612).

41

2.4 Lingual bonded spurs. a and b are examples of lingual bonded spurs bonded to the maxillary and mandibular incisors. C is an example of lingual bonded spurt appliance used to correct anterior tongue posture or digit-sucking habits. d the same subject as in photograph a and b with 8 spurs bonded to the upper and lower incisors. Note the difference in aesthetic between the spurs in and b in comparison to c (McRae, 2010, p. 6).

42

2.5 An illustration of chin cup therapy to correct malocclusion which led to the decrease of the gonial angle (Torres et al., 2006, p. 612).

43

4.1 Incidence of various bites in the sample population (centre), and prevalence of thumb sucking for bite cluster (green indicating there is no history of thumb sucking and red indicating a history of thumb sucking).

58

IX

4.2 Factor analysis and eigenvalues highlighting four or perhaps five key variables.

63

4.3 Scree plot with eigenvalue cut-offs suggesting four principle values for deeper exploration.

64

4.4 The final architecture inclusive of eight variables and a binary outcome

67

4.5 ROC plot with AUC of 0.86 68

4.6 Initial neural network architecture using only 2 inputs, 2 hidden layers of 2 and 1 nodes respectively, and a single binary output

70

4.7 The logistic activation function defines the output of each node based on its input for a single probabilistic layer.

71

4.8 Final neural network architecture using only 2 inputs, 2 hidden layers of 1 node respectively, and a single binary output

71

X

LIST OF TABLES

1.1 Incidence of terminal molar relationships at three stages of occlusion development (Moyers, 1973, p. 135-137).

12

4.1 Demographic characteristics of the sample population. 55

4.2 Descriptive Statistics Summary of the variables and occurrence frequency in the sample population.

57

4.3 Statistical relationship between variables and the type of bite. 59

4.4 Neural analysis and rank of variables against the binary outcome. 66

4.5 Neural analysis and rank of variables against the binary outcome 69

4.6 Validation error tests for the final architecture 72

XI

LIST OF ABBREVIATIONS and ACRONYMS

< Less than

> More than

N Number

% Percentage

AFH Anterior Facial Height

AOB Anterior Open Bite

AUC Area Under Curve

CI Confidence Interval

CO Centric Occlusion

CR Centric Relation

EPI Epidemiological Information

ICP Intercuspation Position

JMP Statistical Analysis Program

NSW New South Wales

OMT Orofacial Myofunctional Therapy

OR Odds Ratio

OSA Obstructive Sleep Apnoea

PFH Posterior Facial Height

ROC Receiver Operating Characteristic

SD Standard Deviation

SDB Sleep Disordered Breathing

SPSS Statistical Package for Social Sciences

TAD’s Temporary Anchorage Device

TAFE Technical and Further Education

TMD’s Temporomandibular Disorders

XII

TMJ Temporomandibular Joint

VHA Vertical Holding Appliance

WHO World Health Organisation

1

CHAPTER ONE

BACKGROUND

2

1.1 INTRODUCTION

Anterior open bite (AOB) is a term used to describe the absence of an anterior

occlusion when all remaining teeth are in occlusion (Proffit, Fields Jr, & Sarver,

2014). It forms one of the main symptoms of an overall dentofacial deformity

(Figure 1.1) (Kim & Sung, 2018). AOB can be complex to diagnose, treat and

stabilise due to abundant interrelated aetiologic factors (Greenlee et al., 2011).

There are two categories that identify this malocclusion; dental/acquired open

bite and skeletal open bite with superimposed craniofacial dysplasia (Lin, Huang,

& Chen, 2013).

Figure 1.1: An illustration of facial and intra-oral photographs displaying the features of a patient with AOB (Kim & Sung, 2018, p. 284).

There is a discrepancy among how AOB has been defined in the literature and

this is reflected in the prevalence ranging between 2.0% and 46% (Peres, Barros,

Peres, & Victora, 2007; Sousa, Ribeiro, et al., 2014; Stahl, Grabowski, Gaebel, &

3

Kundt, 2007; Ciuffolo, Manzoli, Attilio et al., 2005). Nonetheless, most

investigators concur that there needs to be lack of contact between anterior teeth

for it to be classified as an AOB (Cozza, Mucedero, Baccetti, & Franchi, 2005; G.

J. Huang, Justus, Kennedy, & Kokich, 1990; Shapiro, 2002). The variability in

incidence of this malocclusion is likely to reflect variations in age, socioeconomic

status, external environmental and other factors, and may be partly due to the

causative factors (Kharbanda, Sidhu, Shukla, & Sundaram, 1994; Kobayashi,

Scavone Jr, Ferreira, & Garib, 2010; Todor, Vaida, Csep, & Iurcov, 2015).

Non-nutritive sucking habits had been extensively reported in the literature and

was suggested to have an association with craniofacial deformities, mouth-

breathing and malocclusion (Gelgör, Karaman, & Ercan, 2007). It has been

reported that prolonged durations of non-nutritive sucking habits with tongue-

thrust tendencies formed a mechanical obstacle in the anterior teeth eruption

which led to development of malocclusions such as AOB (Helle & Haavikko,

1974; Katz, Rosenblatt, & Gondim, 2004; E. Larsson, 1985; Melsen, Stensgaard,

& Pedersen, 1979).

There are a number of other oral habits that influence development of

malocclusion, including digit and/or thumb sucking, tongue thrusting and forward

posture of tongue, pacifier use, and sucking other objects or toys (Cozza,

Baccetti, Franchi, Mucedero, & Polimeni, 2005; del Conte Zardetto, Rodrigues,

& Stefani, 2002; Góis et al., 2008; Helle & Haavikko, 1974). These habits link to

the age of the child, where it is postulated that as the child advances with age,

the prevalence of malocclusion decreases due to the cessation of non-nutritive

sucking behaviors (Vasconcelos et al., 2011). It is crucial that non-nutritive

4

sucking habits cease at an early age to prevent craniofacial deformities and the

development of malocclusions such as AOB.

1.2 DENTAL OCCLUSION

Following an extensive journey throughout the history of dental practice and

science, occlusion has conquered its role as ‘the medium of dentistry’ (Ricketts,

1969). The study of dental occlusion has been a major subject of interest

throughout the advancement of dentistry (Angle, 1899; Okeson, 2014; Ramfjord

& Ash, 1966; Washburn, 1925). Assessment of occlusion, therefore forms a

clinically significant aspect of all dental disciplines (Gray, 2004).

Occlusion can be simply outlined as the contacts between teeth. Before

illustrating the significance of the various ways in which occlusal contacts are

made, the occlusion needs to be put into context. The masticatory

(stomatognathic) system is predominantly considered to be made up of three

units; the teeth, the periodontal tissues and the articulatory system (Davies &

Gray, 2001). The articulatory system is a congregation that is connected or

interdependent so as to shape a complex unit where the temporomandibular

joints act as hinges, the masticatory muscles as the motors and the dental

occlusion as the contacts (Davies & Gray, 2001).

In mechanical terms, it is evident that the elements of the articulatory system are

inevitably connected. Furthermore, it can be considered that they are obviously

interdependent because an alteration in any part will, therefore, affect the other

two parts, but this effect will not necessarily be adverse (Davies & Gray, 2001).

5

1.2.1 Definitions and Classifications

The term ‘occlusion’ relates to the arrangement of maxillary and mandibular teeth

and the way in which the teeth make contact (Türp, Greene, & Strub, 2008). A

simplified definition of occlusion includes such phrases as the static relationship

(Aidsman, 1977) or any contact (McNeill, 1997) between the incising or

masticating surfaces of the maxillary and mandibular teeth or tooth analogues

(Aidsman, 1977). With epidemiological and clinical but not anthropological

focuses, this study adopted the definition of occlusion as “the static relationship

between the incising or masticating surfaces of the maxillary or mandibular teeth

or tooth analogues” (Ferro et al., 2005).

In a broader sense, the definition of occlusion is not restricted to morphological

tooth contact relationships, but rather encompasses the dynamic morphological

and functional relationships between all constituents of the masticatory system

(Davies & Gray, 2001). This includes teeth and their supporting tissues as well

as the neuromuscular system, temporomandibular joints (TMJs) and the

craniofacial skeleton (Klineberg & Jagger, 2004; McNeill, 1997; Mohl, 1988).

Angle’s classification of malocclusion in the 1890s was an important step in the

development of orthodontics because not only did it subdivide major types of

malocclusion but it also outlined the first clear and simple definition of normal

occlusion in the natural dentition. Angle’s claim was that the maxillary first molars

were the key to occlusion and that the maxillary and mandibular molars should

be related so that the mesiobuccal cusp of the maxillary molar occludes in the

buccal groove of the mandibular molar (Angle, 1900). If the teeth were arranged

6

on a smoothly curving line of occlusion and this molar relationship existed, then

normal occlusion would result (Angle, 1900).

There are two sub-categories of occlusion; static and dynamic (Davies & Gray,

2001). The static occlusion refers to simply when teeth are in contact where the

mandible is closed and stationary, while dynamic occlusion refers to contacts

between teeth when the mandible is moving relative to the maxilla (Davies &

Gray, 2001). When taking into consideration a patient’s static occlusion it is

essential to identify if centric occlusion (CO) occurs in centric relation (CR)

(Davies & Gray, 2001). CO is defined as the occlusion the patient makes when

they fit their teeth together in maximum intercuspation or intercuspation position

(ICP); it is the occlusion that the patient nearly always makes when asked to close

their teeth together (Davies & Gray, 2001). CR is not an occlusion and has

nothing to do with teeth because it is only the ‘centric’ that is reproducible with or

without teeth present (Davies & Gray, 2001). CR is a jaw relationship; it describes

a conceptual relationship between the maxilla and mandible (Figure 1.2) (Davies

& Gray, 2001). CR is outlined in three ways; anatomically, conceptionally (Angle,

1899), and geometrically (Davies & Gray, 2001).

7

Figure 1.2: An illustration of the temporomandibular joint showing the difference in mandibular position between a CO (solid line) and CR (broken line) (Shildkraut, Wood, & Hunter, 1994, p. 336).

Anatomical CR is illustrated as the position of the mandible to the maxilla, with

the intra-articular disc in position, when the condyle head is against the

uppermost part of the distal facing incline of the glenoid fossa (Figure 1.3).

Conceptual CR can be depicted as that position of the mandible relative to the

maxilla, with the articular disc in position, when the muscles that support the

mandible are at their most relaxed and least strained form (Davies & Gray, 2001;

Helland, 1980). This definition is applicable to the perception of ‘ideal occlusion’.

As for geometrical CR, it is defined as the position of the mandible relative to the

maxilla, with the intra-articular disc in place, when the condyle head is in terminal

hinge axis (Davies & Gray, 2001; Helland, 1980).

8

Figure 1.3: Functional anatomy of the temporomandibular joint illustrating the position of the mandible to the maxilla with the intra-articular disc is in place (Helland, 1980, p. 147).

To understand this frequently used definition, it is simple to take into

consideration only one side of the mandible initially. The mandible first opens by

a rotation of the condyle and then a translation that is downwards and forwards

(Davies & Gray, 2001). Hence, when the mandible closes, the terminal closure is

essentially rotational (Davies & Gray, 2001). At this closure phase, the mandible

is implementing a simple arc as the centre of its rotation remains stationary, which

provides the ‘terminal hinge point’ of rotation of the one side of the mandible

(Davies & Gray, 2001). Due to the mandible structure being one bone with two

connected sides, these two terminal hinge points are linked by an imaginary line

known as the terminal hinge axis, which is visualised by imagining the stationary

centres of rotation of each condyle during movement of the mandible in the

rotational phase of movement (Davies & Gray, 2001).

9

1.2.2 Structures Involved in Occlusion Development

To further expand on the extent of structures involved in the development of

occlusion, one needs to take into consideration the soft tissue anatomy and

function, airway function, size of the maxilla and mandible, tooth anatomy

(including malformation), arch form, congenitally missing teeth and rotation of all

teeth (Vu, Roberts, Hartsfield, & Ofner, 2008). All of these parameters need to

be incorporated in the notion of occlusion (Vu et al., 2008). On the other hand,

malocclusion is possibly simpler to define; where one can describe it as a

significant deviation from normal occlusion. Nevertheless, this definition is only

beneficial if one takes into consideration the multiple factors contained in such a

definition. Genetic influences, among many other causes, are suggested to have

a role on the dynamic concepts of the normal occlusion and malocclusion (Davies

& Gray, 2001).

Another factor that plays a role in manipulating the occlusion is known as

macroglossia, which refers to a larger than normal tongue size (Ayers & Hilton,

1976; Reynoso et al., 1993). Congenital macroglossia, which is caused by an

overdevelopment of the lingual musculature or vascular tissues, becomes more

apparent with growth of the child (Ayers & Hilton, 1976; Reynoso et al., 1993). A

tongue that is disproportionately large may lead to both an abnormal growth

pattern of the jaw and malocclusion (Ayers & Hilton, 1976; Reynoso et al., 1993).

10

1.2.3 Development of Dental Occlusion

To simplify the occlusion and malocclusion dynamics further, good insight on the

growth and pattern of occlusion should be understood. The normal range of

overjet in the deciduous dentition ranges between 0 and 4 mm (Leighton, 1977).

One of the morphological differences between deciduous and permanent teeth is

the long axis of the tooth. Generally, overbite and overjet during the deciduous

stage of dentition do not undergo substantial changes unless they are influenced

by environmental factors including habits, dental caries and trauma (Dean, 2015).

The evidence that the width of the palate increases rapidly in the first six postnatal

months, is not necessarily conclusive of a change in the overjet, as the former

appears to play mediolaterally and the latter anteroposteriorly (Dean, 2015).

By three years of age, the occlusion of 20 primary (deciduous) teeth is generally

established. There are three categories that classify the relationship of the distal

terminal planes of opposing second primary molar teeth. A flush terminal plane,

or known as flush terminus is where the anterior-posterior positions of the distal

surfaces of opposing primary second molars are in the same vertical plane

(Leighton, 1977). A mesial step terminus is described as a mandibular second

primary molar terminal plane that is mesial to the maxillary primary terminus

(Leighton, 1977). In addition, distal-step terminal plane outlines the relationship

in which the mandibular second primary molar terminus is distal to the upper

second primary molar terminus. Statistical studies have shown that percentage

of prevalence of these terminal planes are 49% for mesial-step terminus, 37%

are flush-terminus and approximately 14% are distal-step primary terminus

(McDonald, Avery, Stookey, Chin, & Kowolik, 2011).

11

Figure 1.4: Representation of occlusion development of the first molar with illustration of the terminal plane at approximately 5 years of age, and initial contact at approximately 6.5 years and final occlusion at about 12 years (Moyers, 1973, p. 135-137).

The first permanent teeth to develop and arise are the first permanent molars and

are clinically visible at approximately six years of age (Moyers, 1973). The

relationship of permanent first molars is illustrated by one of four categories when

initial occluding contacts occurs during eruption (Figure 1.4) and is classified in

classes (Moyers, 1973). The relationship where the mesial-buccal (m-b) cusp of

the upper first permanent molar contacts at or near the buccal groove of the lower

first permanent molar is known as a class I relationship and occurs in about 55%

of cases. An end on end relationship is where both m-b cusps of both molars

oppose one another and occurs in approximately 25%. A class II relationship is

12

where the upper m-b cusp is anterior (in front of) to the lower m-b cusp, and

incidence is reported in 19% of cases. Class III relationship, occurring 1% of the

population, is where the upper m-b cusp positioned posterior (behind of) to the

lower buccal groove (Carlsen & Meredith, 1960).

Table 1.1: Incidence of terminal molar relationships at three stages of occlusion development (Moyers, 1973, p. 135-137).

Primary terminal place (Age 5 years)

Initial permanent first molar occlusion (6.5 years)

Final occlusion (approx. 12 years)

1% Class III 3% Class III

49% Class I (ms) 27% Class I 59% Class I

37% Flush 49% End-on 39% Class II

14% Class II (ds) 23% Class II

The notion of ideal occlusion development had been explained by Friel (1927),

and by Lewis and Lehman (1929). In addition, Sanin and Savara (1972) had also

outlined that ideal occlusion at a young age predisposes to an ideal occlusion in

adulthood. The occlusion that’s most desirable is a class I ICP, and several

features in the primary dentition, when accurately detected, can establish clinical

signs as to whether a class I relationship of the dentition will ultimately take place.

Foreseeing subsequent arch relationships cannot be utilised as a consistent

diagnostic standard through gum pad relationships due to the dominance of

respiratory and swallowing functions, which are great at birth and hence

unpredictable adjustments in maxillary and mandibular positions occur in first few

years of life (Sanin & Savara, 1972). At three years of age, there is establishment

of the maxilla and mandible relationship with the overall maxilla-mandibular

pattern does not alter substantially thereafter (Sanin & Savara, 1972).

13

One major diagnostic characteristic regarding future occlusion status is the

relationship of the primary terminal planes. The prospect of a class I relationship

developing in the permanent dentition is utmost when a mild mesial-step terminus

exists during the primary dentition stage (Figure 1.4) (Moyers, 1973). A class III

permanent molar relationship will form if there is an exaggerated mesial step in

the primary molars. The likelihood that a class I relationship developing from a

distal-step primary terminus is practically non-existent (Moyers, 1973). The

presence of a distal step is therefore largely prognostic of a developing class II

permanent molar relationship.

On the other hand, another significant diagnostic trait that is prophetic of later

occlusion status is the relationships of the first permanent molars during initial

occluding contact. These erupt at approximately six years of age and the chance

that a class I ICP of the dentition will develop is greatest when a class I

relationship is observed at initial permanent first molar occluding contact (Moyers,

1973). It can be said that occlusion relationship of upper to lower dentition

persists nearly the same throughout the growth period (da Silva & Gleiser, 2008).

Other factors can contribute to this and allow for exceptions. These factors

include environmental, premature loss of primary teeth and congenitally missing

teeth (Northway, Wainright, & Demirjian, 1984).

The developments of dental arch malocclusion or clinically acceptable dental

arches are predictable. The condition of the dental arch at mid-adolescence is

reliant on clinical characteristics that can be simply predicted during the transition

phase dentition (Moyers, 1973). A straightforward technique of evaluating the

dental arch for traits that predispose to malocclusion is to compare the patient’s

14

mixed dentition dental arch with an ideal dental arch pattern. For a seven year

old child, the ideal dental arch pattern should have no rotations, be in tight

proximal contacts, possess specific buccal-lingual axial inclinations and specific

mesial-distal axial inclinations, have even marginal ridges vertically, flat occlusal

plane and excess (positive) leeway space (Anderson, 2007).

Wassell et al., (2008) suggests that the concept of a morphologically correct or

incorrect ICP does not exist. Wassell et al., (2008) further mentions that all of the

orthodontic “classes” are common, including class I relationships being rarely

perfect. There are many normal variations which are consistent with satisfactory

function and oral health (Wassell et al., 2008).

The positions and shapes of teeth define the ICP. In most people, the cusps of

the posterior teeth in one arch fit into the fossae and onto marginal ridges on the

opposing arch in a unique way, just as key fits a lock, providing an ICP that is

highly reproducible and stable (Wassell et al., 2008). A minority of people are

unable to find a single position due to their teeth arrangement and therefore do

not possess a stable ICP (Wassell et al., 2008). The axial inclination is not taken

into consideration to define the “ideal” occlusion. For the majority of people, when

they close their teeth together they always and smoothly end up n ICP (Wassell

et al., 2008). It is further illustrated that the ICP is only consistent and stable when

there are enough teeth in order to define it (Wassell et al., 2008).

15

1.3 MALOCCLUSION

1.3.1 Anterior Open Bite (AOB)

Open-bite relationships are characterized by lack of the teeth in both arches to

contact properly (Figure 1.5) (Cangialosi, 1984). Open bites can be detected in

the anterior or posterior region and may be attributable to supra-eruption of the

adjacent teeth or infra-eruption of the teeth in the area of question. Open bites

can be outcomes of abnormal habits, deviant growth patterns, or an abnormal

tongue position.

Diagnosis of open bites should be viewed first in the context of skeletal structures.

Sassouni (1969) classified open bites into skeletal and dental open bites. The

latter have no significant skeletal abnormality. When the skeletal morphology in

the vertical dimension has been classified successfully, it can be determined

whether or not a dental open bite accompanies the skeletal relationships. Figure

1.6 (Ngan & Henry, 1997) shows that there are multiple variants of this problem.

16

Figure 1.5: Representation of an open-bite pattern using a cephalometric tracing of landmarks and planes (Cangialosi, 1984, p. 30).

Involving AOB, it must be decided whether the open bite is a true skeletal

dysplasia or a habitual problem involving only the dentoalveolar structures. In

addition, any means of identifying the skeletal pattern of an open bite may be

helpful in the possible prevention or early treatment of this condition and also be

a guide in assuring that the mechanics employed will not aggravate the condition.

Many studies have been carried out yielding extensive information regarding the

morphologic characteristics and specific areas of this dysplasia (Cangialosi,

1984).

17

Figure 1.6: This diagnostic flow chart demonstrates the possibilities and relationships between skeletal and dental relationships in open bite malocclusion (Ngan & Henry, 1997, p. 91-98).

1.3.1.1 Prevalence of AOB

In the deciduous dentition, prevalence of malocclusions may be divided into four

major categories: deviations in available space, deviations in the vertical plane,

deviations in the sagittal plane, and deviations in the transversal plane (Koch &

Poulsen, 2009). In the primary teeth, space conditions possess a different

meaning than in the permanent teeth (Table 1.1).

In the deciduous dentition, spacing between the anterior teeth is a normal

anatomical characteristic, while small spaces or crowding in the deciduous front

teeth indicate that this may proceed into the permanent dentition as well. The

18

permanent central incisors will likely resorb both central and lateral primary

incisors during eruption, shifting the lack of space distally in the dental arch. This

lack of space should not be treated in the primary dentition, but closely monitoring

the eruption of the permanent successors is necessary (Koch & Poulsen, 2009).

Vertical plane malocclusions (Table 1.1) do not represent to be problematic in the

deciduous dentition.

Open bite descriptions vary among different authors and researchers. Several

orthodontic specialists define an open bite to be present when there is less than

an average overbite, while others believe an edge-to-edge relationship between

anterior teeth to be an open bite (Subtelny & Sakuda, 1964). In addition, many

researchers have postulated that a certain degree of openness must be present

to classify as an open bite (Subtelny & Sakuda, 1964). Due to varying definitions

of open bite, the occurrence of reported cases vary also and in turn altering

statistics representing the frequency with encountered cases of this abnormal

dental occlusion in the orthodontic practices (Subtelny & Sakuda, 1964).

The prevalence of AOB is high, but is almost always dentoalveolar and most likely

due to sucking habits. AOB closes in most cases when sucking habits diminish

(Moss & Salentijn, 1971). Studies report the range of prevalence for AOB to be

from 6% to 50% for AOB (Akbari et al., 2016; Alonso Chevitarese, Valle, &

Moreira, 2003; Carvalho et al., 2011; Ciuffolo et al., 2005; Corrêa-Faria, Ramos-

Jorge, Martins-Júnior, Vieira-Andrade, & Marques, 2014; Paola Cozza, Manuela

Mucedero, et al., 2005; Dos Santos et al., 2012; Gelgör et al., 2007; Macena,

Katz, & Rosenblatt, 2009; Moss & Salentijn, 1971; Parker, 1971; Sousa, Ribeiro,

19

et al., 2014; Stahl et al., 2007; Urzal, Braga, & Ferreira, 2013; Zuroff et al.,

2010).

This variance is possibly due to different cultural and economic standards

internationally, which may impact on the habits and behaviours of their respective

population (Corrêa-Faria et al., 2014; Sousa, Pinto-Monteiro, Martins, Granville-

Garcia, & Paiva, 2014; Sousa, Ribeiro, et al., 2014). Factors such as ethnicity,

socioeconomic background, environmental influences, and age can impact on

the prevalence. Furthermore, the prevalence differs substantially among studies

depending on how authors describe this abnormal occlusion. Another impact of

low socioeconomic status to take into consideration was accessibility and

affordability of preventative or treatment methods to manage malocclusions such

as AOB.

According to the findings by Ng, Wong, & Hagg (2008), they noted that sucking

habits tend to diminish while oral function matures with age, while individuals from

low socioeconomic backgrounds tend to develop this malocclusion more so due

to mothers needing to work full-time and are unable to provide breastfeeding for

the advised duration. There is, however, no supporting evidence in other studies

to suggest that mothers of only low socioeconomic backgrounds needing to work

and therefore, did not breastfeed for the recommended duration.

The primary dentition stage is the utmost ideal phase for preventive and

interceptive measures (Kobayashi et al., 2010). Gender did not have any impact

on AOB (Machado et al., 2014; Peres, Barros, et al., 2007; Sousa, Lima,

Florêncio Filho, Lima, & Diógenes, 2007), while school type was closely linked,

20

showing those who attended public schools were more likely to develop AOB

than private schools ( Sousa, Pinto-Monteiro, et al., 2014).

1.3.1.2 Development of AOB

The primary dentition role in the formation of permanent occlusion is well

recognised. The substance of primary teeth as “space maintainers” for the

permanent teeth is distinct, particularly following early loss of the primary second

molars due to caries or ectopic eruption of the first permanent first molars.

Nevertheless, the deciduous dentition also acquires its own malocclusions,

which, if untreated, may be transmitted to the permanent dentition (Cameron &

Widmer, 2013). Several of the malocclusions, in particular anterior and posterior

functional cross bites and scissor bites, have the additional disadvantages that

may influence facial growth and development of the occlusion when untreated

(Cameron & Widmer, 2013).

The open bite must be evaluated as a deviation in the vertical relationship of the

maxillary (upper) and mandibular (lower) dental arches. There should therefore

be a certain lack of contact, in the vertical direction, between opposing segments

of teeth. The degree of openness may differ from patient to patient but an edge-

to-edge relationship or some form of an overbite cannot be technically classified

as an open bite (Subtelny & Sakuda, 1964).

Dental open bites are attributed to the unfavourable behavioural habits involving

digit sucking, pacifier use and forward posture of tongue (English, 2002). This

can lead to an under eruption caused by an obstruction prevention the eruption

of the incisor teeth, removing the unfavourable habit will essentially lead to self-

21

correction of the open bite (English, 2002). While, skeletal open bite generally

displays super eruption of the maxillary teeth with an increase in dentoalveolar

heights (English, 2002). A study by Cangialosi (1984) demonstrated that skeletal

open bites display more eruption of molars and incisors in comparison to dental

open bite.

1.3.1.3 Aetiology of AOB

There are several proposed aetiologic factors linked with open bite;

1. Vertical growth deficiencies, these are usually outlined despite varying

beliefs of locating exact area suggesting this deficiency (Subtelny &

Sakuda, 1964). Most authors suggest that the vertical deficiency is located

in the anterior portion of the maxilla (Ackerman & Proffit, 1969; Bergersen,

1988; Samir E Bishara & Jakobsen, 1998; Paola Cozza, Tiziano Baccetti,

Lorenzo Franchi, Manuela Mucedero, & Antonella Polimeni, 2005),

2. Disproportionate muscle growth or abnormal muscle function with an

enlarged, extremely fronted or protrusive tongue function is believed to

inhibit complete eruption of anterior dental units or apply a disfiguring

influence on the sculpting of the anterior denotalveolar processes

(Subtelny & Sakuda, 1964), and

3. Oral habits such as thumb or digit sucking can also play a role (Subtelny

& Sakuda, 1964). If these aetiologic factors are taken into consideration

within the fundamental orthodontic principles, it is not mistaken to suggest

that there seldom will be one single aetiologic factor (Subtelny & Sakuda,

1964).

22

1.3.1.3.1 Skeletal

In a study conducted by Hellman (1931), involving 43 patients with AOB identified

that the treated group of patients displayed equivalent percentage of success to

those who had spontaneous self-corrections in the untreated group. Based on

these observations, he proposed that the skeletal growth deficiencies were the

primary cause of open bite. On the other hand, other authors have suggested

that the main cause of open bite to be due to tongue thrusting (Straub, 1960;

Swinehart, 1942). They have also suggested that this open bite can be corrected

through retraining the tongue and eliminating muscle dysfunction. In contrast,

Subtelny (1973) stated that muscular activity during deglutition is primarily

determined by form. This means that the reason the tongue is thrust forward is

so that it acts as an oral seal which is necessary for deglutition. Hence, Subtelny

(1973) suggested that it is questionable whether the tongue causes this open bite

or acts in reverse.

Furthermore, growth factors and age also play vital roles in the AOB. Worms,

Meskin, and Isaacson (1971) conducted a study involving 1,408 Native American

children. They identified that there was a spontaneous correction of AOB’s in 80%

of the sample as children grow from seven to nine year age group. In addition,

other studies have suggested the tongue to play a major role in swallowing up to

the age of 10 years (Fletcher, Casteel, & Bradley, 1961; Ward, Malone, Jann, &

Jann, 1961). Following this age, this mode of swallowing is decreased remarkably

which aids in the spontaneous correction of AOB (Fletcher et al., 1961; Ward et

al., 1961).

23

In summary, the skeletal open bite is often due to the excessive vertical growth

of the dento-alveolar complex, in particular in the posterior molar region. AOB is

usually caused by a combination of both dental and skeletal factors, it is difficult

to classify it as either skeletal or dental. Aetiology of AOB is caused by a

combination of genetic, anatomic and environmental factors (Lin et al., 2013).

1.3.1.3.2 Oral Habits

Oral habits that affect the dental occlusion include non-nutritive sucking

behaviours such as using a pacifier or finger/thumb sucking. Digit sucking can

develop an asymmetrical AOB which is more pronounced on the side the digit is

being sucked on (Lin et al., 2013). It is duration and frequency of digit sucking is

what leads to AOB.

It has been suggested that six hours or more of daily digit sucking can lead to

malocclusion (Lin et al., 2013). Furthermore, it has been noted that thumb-

sucking behaviours are considered normal in a child that is under the age of three

years (Warren & Bishara, 2002). Prolonged habits of thumb and/or finger sucking

with or without tongue thrusting tendencies can result in obstructing proper

eruption of permanent anterior teeth (Warren & Bishara, 2002).

Some even suggest that oral habits can lead to protrusion of the upper anterior

teeth, leading to lack of contact and thus being classified as an AOB as a result

(Bishara, Warren, Broffitt, & Levy, 2006). Another study found that oral habits

were highly linked to the development of malocclusions such as posterior cross-

bites (Facciolli Hebling et al., 2008; Macena et al., 2009; Scavone-Junior,

Ferreira, Mendes, & Ferreira, 2007). There seems to be an agreement in the

24

literature in that cessation of the unfavourable oral habits such as sucking on

pacifiers, fingers or thumb can lead to self-correction of the AOB (Cardoso, Bello,

Vellini-Ferreira, & Ferreira-Santos, 2014).

1.3.1.3.3 Other Aetiological Factors

There has been an agreement among numerous authors to suggest that non-

nutritive sucking habits as being the consequences of modernization and

industrialization, where more women worked and thus undertaken shorter breast-

feeding periods, favoring the adoption of non-nutritive sucking behaviors

(Vasconcelos et al., 2011). This led to development of AOB malocclusion.

Furthermore, some authors had proposed that AOB is influenced by factors such

as age, ethnicity and dentition (Ciuffolo et al., 2005; del Valle, Dave-Singh,

Feliciano, & Machuca, 2006; Øgaard, Larsson, & Lindsten, 1994; Peres, De

Oliveira Latorre, et al., 2007).

1.3.1.4 Treatment of Anterior Open Bite

Environmental and/or genetic factors may lead malocclusions to develop and a

large number of malocclusions will persist in the permanent dentition, unless they

are treated. Oral habits, reduced activity in jaw muscles, hypertrophic tonsils and

adenoids, dental trauma, early loss of deciduous teeth, and severe chronic

disease in childhood are all categorised under the environmental factors

(Cangialosi, 1984).

During childhood, there is an inconsistency between tongue volume and available

space in the oral cavity. In addition, adenoids are often large in size. Through

reduction of adenoids size and increased oral space during growth, a large

25

number of these AOB’s spontaneously close. While skeletal open bite may be the

result of a posterior rotation of the mandible during growth (Cangialosi, 1984).

AOB treatment is complex in orthodontics. There are several approaches in

treating this malocclusion used in current orthodontic practices. It has been

suggested to be favourable that patients cease oral habits such as thumb/finger

sucking before commencement of orthodontic treatment (Dellinger, 1986; Ngan

& Fields, 1996). While orthognathic surgery is indicated in non-growing patients

with a skeletal AOB. The aim of utilising orthognathic surgery is to reduce the

vertical skeletal growth with intra-oral and extra-oral forces (Dellinger, 1986; Ngan

& Fields, 1996). For the growing patients, few techniques have been suggested

to maintain vertical growth, including vertical holding appliance (VHA), posterior

bite blocks and functional appliances such as activators, bionators and Fränkel

regulators (Dellinger, 1986; Ngan & Fields, 1996).

In adult patients, orthognathic surgery is often indicated for significant open bites

and aesthetic needs. Surgeries involve both the maxilla and mandible, anterior

maxillary and mandibular surgeries as well as combine surgeries of mandible and

temporary anchorage devices (TADs) (Bell & Dann, 1973; Brammer et al., 1980;

Hiranaka & Kelly, 1986; Taylor, Mills, & Brenner, 1967; Togawa, Iino, & Miyawaki,

2010).

Other mechanisms that correct functional habits include the prevention of the

tongue to rest on the anterior teeth ( Haryett, Hansen, Davidson, & Sandilands,

1967). These are best identified as lingual or palatal cribs (Subtelny & Sakuda,

1964) and spurs (Justus, 2001; Meyer-Marcotty, Hartmann, & Stellzig-

26

Eisenhauer, 2007). There is an agreement until automatic movements are

established, these devices should be fixed to re-educate the oral function (Meyer-

Marcotty et al., 2007; Nogueira, Mota, Nouer, & Nouer, 2005b). The palatal or

lingual cribs are designed to prevent the tongue from resting on the teeth and in

turn correcting the AOB (Subtelny & Sakuda, 1964).

These structures are smooth and purposefully enable the tongue to rest on them

so that in several cases it may block the functional re-education of the tongue.

Hence the tongue then returns to its original position resulting in relapse of AOB

(Rogers, 1927). While spurs stimulate a change in the tongue resting position,

hence enabling tooth eruption and closure of the open bite. This change of tongue

position modifies sensory perception by the brain, thus creating a new motor

response which can be permanently imprinted by the brain (Justus, 2001; Meyer-

Marcotty et al., 2007). This clarifies the permanent change in tongue posture

created by spurs and resulting in AOB treatment stability (Justus, 2001; Meyer-

Marcotty et al., 2007).

Other treatments include behavioural modifications to eradicate oral habits or

abnormal functions. Orofacial myofunctional therapy (OMT) is utilised to modify

function and is composed of a set of exercises that re-educate orofacial muscles

in swallowing, speech and resting posture (Franco, Araújo, & Habib, 2001; Miller,

1969; Subtelny & Sakuda, 1964). These are generally combined with orthodontic

treatment that involves extruding the anterior teeth or intruding the molars, and

surgical treatment of the basal bones (Greenlee et al., 2011). The only

agreement that seems to be established is that treatment of the AOB is

27

demanding and has poor stability (Denison, Kokich, & Shapiro, 1989; Huang et

al., 1990; Lopez-Gavito, Wallen, Little, & Joondeph, 1985; Zuroff et al., 2010).

1.3.2 Other Malocclusions

There are wide variations of the epidemiological data on malocclusion. This is

partly due to the population being screened, and partly on the method of

recording these malocclusions (Tschill, Bacon, & Sonko, 1997). Tooth to jaw

divergence is one of the most common features seen in modern society. The

genetic factors as well increased outbreeding have been suggested to have

impact on the prevalence of crowding in the dentition in today’s populations

(Tschill et al., 1997).

Numerous studies have been published on the prevalence of malocclusions in

various populations. The reported incidence is suggested to range from 39% to

93% (Johannsdottir, Wisth, & Magnusson, 1997; Kerosuo, Laine, Nyyssonen, &

Honkala, 1991; Otuyemi & Abidoye, 1993; Tschill et al., 1997), identifying that the

majority of children have irregular teeth alignment and occlusal relationships that

diverge from the ideal. It is noted that ethnic groups, different demographics as

well as difference in the recording criteria are the most important factors outlining

these differences in incidence rates.

It is noted that the prevalence of crowding in Caucasian populations to be at its

highest levels later in life (Helm, 1968; Infante, 1976; Thilander & Myrberg, 1973).

Individuals who display contact between their maxillary primary teeth are more

likely to develop crowding in the permanent dentition (Helm, 1968; Infante, 1976;

Thilander & Myrberg, 1973). Leeway space as well as surface remodelling that

28

accompanies the eruption of the maxillary permanent central incisors may result

in development of space conditions that prevents crowding from taking place

(Tschill et al., 1997).

A study by Tschill et al. (1997) examining malocclusion of children aged four to

six years found that a normal protrusion of the maxillary incisors (overjet of 1-

3mm) accounted for 76% of their studied population, while an excessive overjet

(6mm or more) was found in only 3.7% of the same studied population. The same

conditions were noted in a Finnish study of children aged three years, which

found 2.1% of the population to have an excessive overjet of 6mm or greater

(Järvinen & Lehtinen, 1977). It is suggested that the frequency of excessive

overjet for the deciduous dentition is an inaccurate replication of conditions

accompanying the permanent dentition, where it is expected that prevalence of

malocclusions such as excessive overjet to increase with maturation (Tschill et

al., 1997).

There were no differences noted on the prevalence of Angle Classes II and III in

Europeans and white Americans (Thilander, Pena, Infante, Parada, & de

Mayorga, 2001). The noted difference, however, was between the developmental

stages where there was a decreased prevalence of Class II, but increased

prevalence of Class III, from the late mixed to the permanent dentition (Thilander

et al., 2001). This is possibly due to a growth spurt in the mandible. The reported

prevalence of class III malocclusion was estimated to be 3.7% with an increase

in prevalence with ageing (Thilander et al., 2001). While class II occlusions (i.e.

deep bite) had a reported prevalence of 19% to 36% (Foster & Hamilton, 1969;

Humphreys, 1950; Infante, 1975; Ravn, 1975; Tschill et al., 1997).

29

1.4 FACTORS AFFECTING MALOCCLUSION

Medical studies have outlined the significance of innate psychological attributes

such as self-esteem and its role in predicting the effect of health conditions on

the quality of life (Foltz, 1987; Katz, Rodin, & Devins, 1995). There are several

studies that have examined the associations between self-esteem, effects on

quality of life and dental occlusion. A Brazilian study of school children identified

that children from lower socioeconomic backgrounds were more aware and

sensitive to the aesthetic impacts of their malocclusion (Marques, Barbosa,

Ramos-Jorge, Pordeus, & Paiva, 2005). In another study in Nigeria, similar

findings were reported in that children from higher socioeconomic backgrounds

did not express concerns regarding their malocclusion ( Onyeaso, 2003).

Furthermore, socioeconomic inequalities remains to be a challenge in both

developed and underdeveloped countries (Cardak & Ryan, 2006; Marks,

Cresswell, & Ainley, 2006). In Australia, there is significant under-representation

of people from low socioeconomic backgrounds in higher education (James,

2000; McMillan & Western, 2000). Moreover, one of the most crucial issues of

health in the Australian population is the large geographical area and the

population dispersal. The high cost of dental treatment and lack of services

available is seen in numerous regional, rural and remote locations in Australia

(Steele, Pacza, & Tennant, 2000).

It is also suggested that individuals residing in communities where the closest

public health clinics to be more than 200km away were those from lower

socioeconomic backgrounds and at higher risk for health issues, including oral

30

health (Perera, Kruger, & Tennant, 2010). Hence individuals with limited

disposable incomes and geographic location are disadvantaged from regular

access to healthcare. The majority of dental practitioners reside in urban

communities, with fewer numbers seen in regional, rural and remote locations

(Steele et al., 2000). This thus leads to increased dental care costs as well as

lack of proper access respective of the population need in the regional, rural and

remote communities.

The sample population chosen for this study is from Orange, a regional town in

New South Wales, located in the central west of the state, a diverse community

of people with high socioeconomic status and people with low socioeconomic

status. The regional town has a dental school as well as private and public dental

services.

31

CHAPTER TWO

LITERATURE REVIEW

32

2.1 OPEN BITE MALOCCLUSION

For over a century, issues relating to dental occlusion have been widespread

controversies. Such controversies have impacted on the health of the oral cavity

at varying degrees, commencing with orthodontic matters during childhood and

proceeding to occlusal evaluations of adult patients in general dental practice.

Furthermore, the necessity to carry out complex restorative dentistry demands

critical thinking to establish optimum results.

Restorative dentistry is the restoration of a tooth to or close to its original form by

means of metallic, porcelain, synthetic, resin or inlay materials. In addition,

patients whose masticatory system has developed pain and dysfunction

(temporomandibular disorders, TMDs), there seems to be a high likelihood that

their problems would be assessed and managed with some occlusal concept

(Türp, Greene, & Strub, 2008).

On the other hand, the dental open bite is generally accompanied by normal

craniofacial configurations, with incisors that are proclined (protruding forward)

and under-erupted anterior teeth as well as a normal molar height with thumb-

sucking or other oral habits (Beane, 1999). The majority of open bites contain

both dental and skeletal characteristics (Beane, 1999). While dental open bites

can be treated with orthodontic or behaviour shaping strategies, the skeletal open

bite requires a more complex approach combining orthodontic and orthognathic

surgical procedures to reach function, aesthetics and stability (Frost, Fonseca,

Turvey, & Hall, 1980; Lawry, Heggie, Crawford, & Ruljancich, 1990).

33

Figure 2.1: Comparison between ideal class I anterior occlusion (A) and anterior open bite malocclusion (B) (Ackerman & Proffit, 1969, p. 445).

Figure 2.2: An illustration of AFH: Anterior facial height, and PFH: Posterior facial height, the objective of treatment is to maintain AFH and to improve PFH (Horn, 1992, p. 181).

34

2.1.1 Prevalence of AOB

Given the above definitions, the prevalence of AOB differs substantially among

studies depending on how authors describe this abnormal occlusion. The word

‘malocclusion’ can be subjective, as the notion of ‘ideal’ occlusion is a rare

incident and hence slight occlusal variations do not necessarily lead to specific

health risks. Having said that, the AOB is described as abnormal as it impacts on

the patient’s function, speech, mastication, future dental health risks and

aesthetics (Mohlin & Kurol, 2002). Reported prevalence in the population is

estimated to range from 2% to 46% (Akbari et al., 2016; Alonso Chevitarese et

al., 2003; Carvalho et al., 2011; Ciuffolo et al., 2005; Corrêa-Faria et al., 2014;

Cozza, Mucedero, et al., 2005; Dos Santos et al., 2012; Gelgör et al., 2007;

Grabowski, Stahl, Gaebel, & Kundt, 2007; Macena et al., 2009; Moss & Salentijn,

1971; Parker, 1971; Sousa, Ribeiro, et al., 2014; Stahl et al., 2007; Urzal et al.,

2013; Zuroff et al., 2010).

Numerous factors affect the open bite, including age, gender, non-nutritive

sucking habits, to mention a few. Factors such as age can impact on prevalence,

as sucking habits and oral function mature with age. At the age of six, the AOB

presents as low as 4.2%, while at age 14 years the prevalence declines to 2%

(Cozza, Mucedero, et al., 2005). In the American population, the prevalence

detected was ethnicity-dependent with 3.5% present in Caucasian children while

16.5% in Afro-descendent children (Zuroff et al., 2010). Although the prevalence

is low, the necessity to treat this malocclusion is very common with around 17%

of orthodontic cases having AOB (Zuroff et al., 2010). Another study found that

prevalence of AOB to be 21% in children aged three to five years (Sousa, Ribeiro,

et al., 2014).

35

There are many factors that can influence the discrepancy in the prevalence

(Heimer, Tornisiello Katz, & Rosenblatt, 2008; Macena et al., 2009). Varying

cultural and economic standards, socioeconomic backgrounds, ethnicity, age,

location and other social demographics and environmental influences all

contribute to the alteration of the reported prevalence in the population (Machado

et al., 2014; Øgaard et al., 1994; Sousa, Ribeiro, et al., 2014).

2.1.2 Prevalence of Non-Nutritive Sucking Habits

Sucking behaviours among infants and young children primarily originate from

the physiological need for nutrients. The current understanding of child

development also suggest that the sucking behaviours also develop from the

psychological needs. Infants possess the natural biological drive for sucking

(Johnson & Larson, 1993). This sucking urge can be satiated through nutritive

sucking (breastfeeding and/or bottle-feeding), as well as non-nutritive sucking

(finger/thumb-sucking, pacifier use, or toys). These behaviours are considered

normal in infants and young children, however persisting behaviour for a long

duration may impact on the developing orofacial structures and occlusion (Adair,

Milano, Lorenzo, & Russell, 1995; Larsson, 1983; Lindner & modѐer, 1989;

McRae, 2010; Øgaard et al., 1994; Ravn, 1976).

An early Swedish study on prevalence of non-nutritive sucking habits found a

pacifier sucking prevalence to be 12%, while digit sucking prevalence to be 50%.

Higher proportions of thumb-sucking habits were reported from other locations

with either little or no pacifier use (De Boer, 1976). Over the decades, these

36

trends have dramatically changed, and prevalence of pacifier use up to 70% has

been more commonly evident (Larsson & Dahlin, 1985; Ravn, 1974).

A Danish study on non-nutritive sucking habits prevalence found that from 70%

to 90% of Danish children had history of some form of non-nutritive sucking

behaviours. (Ravn, 1974). Another study by Svedmyr (1979) involving three to

five year old Swedish children, found that only 14% of children had non-nutritive

sucking habits. Out of the 14%, 62% had history of pacifier use. While another

Swedish study noted the prevalence of non-nutritive sucking habits of four year

old children was 88%, with 48% continuing this habit at the age of four, but also

found the majority or participants had pacifier use habits, accounting for 78% of

those with habits (Modёer, Odenrtck, & Lindner, 1982). This study is in agreement

with the Danish study in the extent of prevalence in the studied population, but in

agreement with the earlier Swedish study on the pacifier use predominance of

non-nutritive sucking habit.

There is an equal distribution of non-nutritive sucking prevalence among boys

and girls. It has also been noted that when infants initially develop the pacifier

sucking habits, its intensity is generally low in the first few weeks (Larsson, 1983;

Larsson & Dahlin, 1985). And most children tend to cease the pacifier habits at

age two to three years. In a retrospective study involving 920 Swedish children

aged nine years, Larsson (1986) reported that 351 out of the 412 (85%) children

who displayed pacifier sucking habits had ceased prior to turning four years. After

six years of age, 11 (3%) were still using pacifiers, and, at age nine, only one girl

still continued the habit (Larsson, 1986).

37

In recent societies, literature reported between 10% and 34% of children carry

out thumb/finger sucking during their first year of life (Bishara et al., 2006;

Cardoso et al., 2014; Franco & Gorritxo, 2012; Heimer et al., 2008). While in more

traditional societies, digit/thumb-sucking habits are not commonly present. There

are comparatively very few studies carried out in the United States on prevalence

of non-nutritive sucking habits. Infante (1976) investigated children aged two to

five years and found that 19% had active finger/thumb-sucking habits, with a

higher proportion being girls displaying this habit. While pacifier use was not

recorded, it was suggested that the majority of these children used pacifiers (

Infante, 1976).

2.1.3 Correlations of AOB and Determinant Factors

Several aetiologic factors linked with open bite have been proposed. These

include genetic, anatomic and environmental factors. When taking the genetic

factors into consideration, the open bite is mainly associated with patients’

unfavourable growth capacity and heredity (Björk, 1969; Sassouni, 1969;

Subtelny & Sakuda, 1964). A detailed family history as well as radiographic and

cephalometric analyses are hence necessary to identify whether there is a

genetic factor present (Ellis & McNamara, 1984).

The anatomic factor includes size and position of the tongue has been suggested

to affect both the dental and skeletal factors (Kawakami, Yamamoto, Noshi,

Miyawaki, & Kirita, 2004). Furthermore, macroglossia, which is an unusually

enlarged tongue, has also been proposed to influence AOB (Miyawaki, Oya,

Noguchi, & Takano-Yamamoto, 2000). Reports identify that in individuals with

AOB, a strong relationship between the angle of the mandible plane, mandibular

38

ramus height, or the maxillary anteroposterior dimension and front section of the

dorsal surface of the tongue movement during swallowing (Fujiki et al., 2004).

In addition, several anatomic ailments including enlarged tonsils and/or

adenoids, swollen nasal turbinates and nasal septums that are deviated may

impact on normal upper respiratory nasal function (Watson, 1981). Consequently,

due to upper airway obstruction, mouth-breathing can take place and, in turn lead

to AOB; however, a direct link has not yet been proven (Vaden & Pearson, 2002).

In contrast, environmental factors such as thumb and finger sucking, forward

posture of tongue and tongue thrust have all been suggested to cause AOB

(Popovich & Thompson, 1973; Straub, 1960, 1961, 1962). Digit sucking had been

said to cause an asymmetrical AOB that is worst on the side where the digit

sucking takes place. Having said that, not all thumb or finger suckers acquire an

AOB; this is more dependent on frequency and duration of the habit (Lin et al.,

2013).

Earlier studies suggests a relationship between non-nutritive sucking habits and

occlusal abnormalities, particularly AOB, increased overjet (protrusion) and

Angle’s class II canine and molar relationship (E. Larsson, 1978). Furthermore, it

has been reported that those who suck for duration of six hours or longer a day

leads to considerable malocclusions (Lin et al., 2013; Popovich & Thompson,

1973). A forward tongue posture, which describes the state where the tongue

rests between the incisors may lead to obstruction of incisor eruption can cause

AOB (Lin et al., 2013; Straub, 1960, 1961). In addition, tongue thrust, whereby

39

the tongue moves forward during deglutition can also lead to AOB (Lin et al.,

2013; Straub, 1962).

2.1.4 Treatment Options

Due to the above mentioned etiologic factors, several treatment options have

been proposed for treatment and/or management of the AOB malocclusion. The

treatment options include behavioural modifications to eradicate oral habits or

abnormal functions and re-educate oral muscles during swallowing and

deglutition (Barbre & Sinclair, 1991; Benkert, 1996; Huang et al., 2015; Huang et

al., 1990; Ngan & Fields, 1996; Smithpeter & Covell, 2010; Van Dyck et al., 2016),

orthodontic treatment that involves extruding the anterior teeth or intruding the

molars (Bondemark et al., 2007; Cooke, 1980; Epker & Fish, 1977; Haralabakis

& Papadakis, 2005; Ng et al., 2008; Swinnen et al., 2001), and surgical treatment

of the basal bones (Epker & Fish, 1977; Greenlee et al., 2011; Haralabakis &

Papadakis, 2005; Haymond, Stoelinga, Blijdorp, Leenen, & Merkens, 1991;

Swinnen et al., 2001). The only agreement that seems to be current is that

treatment of the AOB is demanding and has high rates of relapse (Denison et al.,

1989; Huang et al., 1990; Lopez-Gavito et al., 1985; Zuroff et al., 2010).

Other mechanisms that correct functional habits include the prevention of the

tongue to rest on the anterior teeth (Haryett et al., 1967). These are best identified

as lingual or palatal cribs (Figure 2.3) (Subtelny & Sakuda, 1964; Torres et al.,

2006) and spurs (Justus, 2001; Meyer-Marcotty et al., 2007). Cribs are usually

attached to the palatal surface of the upper arch and allow the sucking to stop as

they act as a digit-inhibiting tool (Cozza, Baccetti, Franchi, & McNamara, 2006;

Haryett, Hansen, & Davidson, 1970; Huang et al., 1990; Parker, 1971; Villa &

40

Cisneros, 1996). The palatal or lingual cribs are also designed to prevent the

tongue from resting on the teeth and in turn correcting the AOB (Subtelny &

Sakuda, 1964). These structures are smooth and purposefully enable the tongue

to rest on them so that in several cases it may block the functional restoration of

the tongue. Hence the tongue then returns to its original position resulting in

relapse of AOB (Rogers, 1927)

There is an agreement until automatic movements are established, these devices

should be fixed to restore the oral function (Meyer-Marcotty et al., 2007;

Nogueira, Mota, Nouer, & Nouer, 2005). A study conducted by (Giuntini, Franchi,

Baccetti, Mucedero, & Cozza, 2008) described the use of crib therapy with two

different approaches; fixed with a quad-helix, or removable using a removable

plate. The crib attachment to the quad-helix showed greater effectiveness than

the removable plate with fixing the AOB.

This could be due to factors such as compliance, where the removable plate

depends on duration of patients wearing it, while the quad-helix is fixed and has

free-compliance factors (Cozza et al., 2006). In spite of a not so significant

difference between both methods, a previous study proved that the quad-helix to

be clinically successful in 90% of patients with AOB as opposed to 60% for the

removable plate with the crib attachment (Cozza et al., 2006).

41

Figure 2.3: Maxillary palatal crib. The extensive dimension vertically allows ample incorporation of the open-bite region (Torres et al., 2006, p. 612).

Spurs on the other hand were first described by Rogers in 1927 in treating three

AOB cases (Rogers, 1927). These spurs were bonded to a palatal arch and

positioned from canine to canine (Figure 2.4) (McRae, 2010). All cases were fixed

through normalising the tongue posture. Numerous types of comparable

apparatuses were later explained in which spurs can be welded to the lingual

surfaces of maxillary incisor bands or attached to palatal or lingual arches or,

otherwise fused to the lingual or palatal surfaces of the incisors (Nogueira et al.,

2005).

In spite of their effectiveness, treatments of AOB using spurs are sometimes seen

as traumatic (Parker, 1971; Subtelny & Sakuda, 1964) even though no reports

have yet to mention any pain of injury caused to the tongue (Justus, 2001). Spurs

stimulate a change in the tongue resting position, hence enabling tooth eruption

and closure of the open bite (Justus, 2001).

42

Figure 2.4: Lingual bonded spurs. a and b are examples of lingual bonded spurs bonded to the maxillary and mandibular incisors. C is an example of lingual bonded spurt appliance used to correct anterior tongue posture or digit-sucking habits. d the same subject as in photograph a and b with 8 spurs bonded to the upper and lower incisors. Note the difference in aesthetic between the spurs in and b in comparison to c (McRae, 2010, p. 6).

Research had previously shown that tongue activity and position to play a key

role in the challenges associated in reaching long-term stability of AOB treatment

(Dung & Smith, 1988; Haryett et al., 1967; Nogueira et al., 2005). It was hence

decided that utilising banded-spur appliances correct the anterior tongue

pressure and preserve long-term stability of modifying the AOB (Haryett et al.,

1967; Huang et al., 1990). Using the lingual spurs had led to AOB closure through

preventing the tongue pressure on the anterior dentition as well as influence on

the patient to discontinue digit-sucking by functioning as a barrier (Haryett et al.,

1967; Huang et al., 1990).

A study conducted by Cassis, de Almeida, Janson, de Almeida-Pedrin, and de

Almeida (2012) showed significant improvement in the correction of AOB with

43

spur treatment. There was significant reduction in the gonial angle, increased

overbite, palatal tipping of the maxillary incisors and vertical dentoalveolar

development of the mandibular and maxillary incisors (Cassis et al., 2012).

Moreover, when a chincup was incorporated in the treatment it led to a greater

decrease of the gonial angle (Cassis et al., 2012; Huang et al., 1990).

Figure 2.5: An illustration of chin cup therapy to correct malocclusion which led to the decrease of the gonial angle (Torres et al., 2006, p. 612).

This change of tongue position modifies sensory perception by the brain, thus

creating a new motor response which can be permanently imprinted by the brain

(Justus, 2001; Meyer-Marcotty et al., 2007). This clarifies the permanent change

in tongue posture created by spurs and resulting in AOB treatment stability

(Justus, 2001; Meyer-Marcotty et al., 2007).

2.1.5 Burdens of AOB on the Community

Literature have shown a strong association between self-esteem and

malocclusion, particularly AOB, protrusion (overjet) and Angles Class III

44

malocclusions. It is suggested that early treatment of children with hyperdivergent

skeletal phenotypes, such as in AOB, is beneficial in that it enhances physical

appearance and improve self-esteem for the child (English, 2002). Furthermore,

prolonged non-nutritive sucking habits, which essentially leads to malocclusions

such as Angles Class II and AOB is not socially accepted. This can generate

negative response and thus affect the child’s self-esteem.

In contrast, children who had undergone surgical and/or orthodontic treatments

to correct AOB have reported to have significant improvement in their facial

appearance, self-confidence and social interactions (Hoppenreijs et al., 1999). In

addition to the physical appearance issues, there is a financial burden associated

with the management and treatment of AOB, in that treatment requires

multidisciplinary approach, in which individuals from regional, rural and remote

communities are unable to afford or access in terms of their geographic location

and disposable incomes.

2.2 STATE OF THE PROBLEM

In terms of the research methodologies, all studies displayed various prevalence

rates of AOB in the respective populations studied as well as the link and effects

of several determinants, including, but not limited to digit/thumb sucking, bottle-

feeding, pacifier use, mouth-breathing tendencies, and social demographics.

AOB has long been regarded as a complex malocclusion to treat/manage with

correction being highly prone to relapse and thus prevalence is difficult to assess

(Burford & Noar, 2003; Epker & Fish, 1977; Subtelny & Sakuda, 1964). This is

due to a multifactorial aetiology, involving skeletal, dental, neurologic, habitual

and respiratory (Burford & Noar, 2003; Cooke, 1980; Subtelny & Sakuda, 1964).

45

Furthermore, very limited literature discussed the extent of prevalence associated

with AOB amongst children with mixed dentition and its relation to the causes by

environmental factors such as finger or thumb-sucking oral habits. Moreover, to

the best of our knowledge, there is a lack in the literature regarding the

prevalence of AOB and non-nutritive sucking in children living in regional and/or

rural communities. In this study, the growing patient (age seven to 12 years) will

be the target group, where children from the regional town of Orange, New South

Wales, Australia, will be involved in identifying prevalence of this malocclusion

amongst this age range.

In conclusion, this review suggests that there is considerable evidence on the

influence of thumb sucking on the development of AOB. There is a paucity of

research that outlines the main cause of AOB as well as the prevalence of it in

the population, with some suggesting the prevalence of AOB to range from 1.5%

to 46%.

There is also limited literature on effects of AOB on the community, particularly in

regional and rural geographic locations. There is a need for a robust study to

evaluate the association between non-nutritive sucking habits, particularly thumb-

sucking and AOB, and that the prevalence of AOB in those individuals. The

current study will assess the association between non-nutritive sucking habits on

AOB and take into consideration environmental influences.

46

CHAPTER THREE

METHODOLOGY

47

3.1 RESEARCH QUESTION

The purpose of the research was to identify the prevalence of the non-nutritive

sucking habits (such as finger/thumb-sucking, pacifier, and other objects) and

determinants on AOB in primary school children aged seven to 12 years.

3.2 AIMS and OBJECTIVES

1. To report and evaluate the prevalence of oral habits and AOB in children

aged seven to 12 years.

2. To investigate the clinical occlusal relationship and oral habits in children

aged seven to 12 years.

3. To investigate the association between non-nutritive sucking and AOB in

children aged seven to 12 years.

3.3 STUDY VARIABLES

The dependent variable in the present study was AOB. AOB was measured

against all other variables, including thumb-sucking, duration of thumb-sucking,

age of onset of thumb-sucking, non-nutritive sucking such as pacifier use or other

objects, feeding modalities (breastfed, bottle-fed, mixed-fed), sleeping issues,

surgical procedures and orthodontic intervention. Furthermore, child’s age,

gender, sequence within their family household and the highest level of education

of the parent completing the form were assessed.

3.4 OVERVIEW OF METHOD

The sample was chosen from a regional town located in the central west of New

South Wales that is representative of many regional towns in Australia in terms

of population size and distribution of social demographics. It has been reported

48

that there is lack in number of healthcare services and affordability in regional,

rural and remote towns of Australia. Australia is one of the most sparsely

populated countries in the world, comprising of only two individuals per square

kilometre, with the majority of the population (86%) concentrated in urban

locations (Perera et al., 2010). It is noted that Australians are one of the healthiest

populations in the world, but there are well-documented proof to suggest that

there is inequality and inequity of distribution to healthcare service access, with

oral health being one of them (Spencer, 2004; Spencer & Harford, 2007). These

aspects led to the selection of Orange, New South Wales.

3.5 DATA COLLECTION

The data collection took place between August and December 2018. All public

and private primary schools in Orange, New South Wales were invited to

participate in the study, which comprised of 6 public and 6 private primary

schools. Data on the schools present in the region were obtained from The

Department of Education New South Wales. Data on enrolment numbers of

children in those schools were extracted from Extracted from NSW Health

Education Public Schools and NSW Public School February Census Enrolment

data.

Each school was provided with an information sheet on the research project. An

appointment with the school principal was made to formally introduce the

research and purpose of the research. The principal was then given an

information sheet and a consent form to complete and return by mail if agreeing

to participate in the study. One primary public school accepted to participate in

the study. Children enrolled were all given an information sheet, consent form

49

and questionnaire inside an envelope to take home. Parents/guardians of

children enrolled, who accepted to participate completed the questionnaire and

consent form. They then returned it in the return envelope provided and were

instructed to place it in a collection box at the school office.

The questionnaires included questions regarding age and sequence of child

within their family household, highest schooling level of parent completing the

questionnaire, child’s milk feeding patterns (natural and/or artificial), respiratory

aspects, history of ear disease, adenoids or tonsil removal, non-nutritive sucking

habits (pacifier use, digit/thumb-sucking) as well as duration and frequency of the

habits (Appendix 3). Parents/guardians were also given illustrations of different

dental bites and were provided with step-by-step instructions on how to identify

and select which category best describes their child’s dental bite (Appendix 4)

(Proffit et al., 2014). A contact number was provided to parents in the event of

requiring some clarification on any aspect of the questionnaire.

Socio-demographic factors, level of parents’ education, as well as the child’s date

of birth and gender were collected to obtain accurate information on the

prevalence based on age, gender and socioeconomic determinants. In addition,

factors regarding both method and duration of the infant feeding modality (Galán-

Gónzalez, Aznar-Martin, Cabrera-Dominguez, & Dominguez-Reyes, 2014).

Concerning the non-nutritive sucking, parents/guardians were asked whether

their children regularly sucked on pacifiers and/or developed finger sucking

habits.

50

Data were then analysed. The participants who were included in the study were

children attending a public primary school in Orange, New South Wales. The

children targeted were between the ages seven and 12 years (males and

females). The questionnaire as well as the inclusion and exclusion criteria were

designed based on previous studies (Cardoso et al., 2014; Charchut, Allred, &

Needleman, 2003), but were slightly modified to fit the purpose of the present

study.

3.6 SELECTION CRITERIA

Children with grossly decayed anterior teeth, cleft lip/palate, as well as language

barrier, non-compliant and intellectual disability, were excluded from the study. In

the protocol for the pilot study, dental decays were to be examined and identified

by the researcher; the clinical examination was replaced with a parent report and

none of the parents reported any grossly decayed anterior teeth in the child’s

mouth. Decayed teeth were identified as extensive tooth decay that results in

near complete destruction/loss of the crown due to caries. The criteria were

based on excluding any variations that may influence the occlusion of those

children. Furthermore, excluding language barrier allows for fully informed

consent by parents/guardians and children in the participation of this study.

The criteria aimed to prevent deviations and minimise errors (Lochib, Indushekar,

Saraf, Sheoran, & Sardana, 2015). The inclusion criteria were based on young

children that are old enough to have coherence to comply with the study and have

a mixed dentition and young enough to not be indicated for orthodontic treatment.

At the age of 12, children who still present with a non-functional dental bite

(malocclusion) are indicated for orthodontic intervention (Proffit et al., 2014). The

51

prevalence of the occlusal disharmony which includes AOB, overjet (protrusion),

cross-bite and deep bite were noted. The terms in lay language were used in the

questionnaire to help parents and guardians to understand and consequently

‘overjet’, ‘under bite’ and ‘over bite’ were used to indicate protrusion, cross-bite

and deep bite, respectively.

52

3.7 STATISTICAL ANALYSIS

The statistical analysis was undertaken using JMP software (JMP®, Version 14.

SAS Institute Inc., Cary, NC, 1989-2019). An artificial neural network was

developed and trained using Neural Designer Software (Neural Analyser version

2.9.5) to better understand the multi-variate relationship amongst variables.

The statistical significance was calculated using Chi-Square analysis for nominal

data and Student’s t test for continuous data. The Pearson Chi Square (X2) test

was employed for categorical data with normal distribution and the Likelihood

Ratio Chi-Square (G2) test for categorical data without normal distribution. The F

test analysis of variances was used to determine statistically significant

differences within grouped data. A P value less than 0.05 was considered

significant.

53

3.8 ETHICAL CONSIDERATIONS

The research study was first approved by the Ethics committee, Charles Sturt

University, protocol number H17123 (approved end date November 2019).

Participants had the right to refuse participation in the study and the right to pull

out of the study at any point during the research being conducted. No personal

information was collected or distributed. All data collected were kept in a safe,

password protected file, accessible only by the research team.

54

CHAPTER FOUR

RESULTS

55

4.1 DESCRIPTIVE ANALYSIS

A total of 208 children aged between seven to 12 years participated in the study.

The demographic characteristics are summarised in Table 4.1. The mean age of

the participants was nine with a 95% confidence interval (CI) of the mean of 8.8-

9.2 years. Of the 208 participants, 51.4% were female, 47.1% male and 1.4% did

not identify by gender. With respect to the sequence within the family unit each

child was born, 68 (32.9%) were second-born, 54 (26.1%) were third-born, 53

(25.6%) first-born, 25 (12.1%) fourth-born, six (2.9%) fifth-born and only one

sixth-born. The highest educational level for the parents of the participants

involved included 28 (13.5%) completing secondary school, 108 (51.9%)

completed TAFE qualifications, 53 (25.5%) completed tertiary education and 19

(9.1%) completed postgraduate education (Table 4.1).

Table 4.1: Demographic characteristics of the sample population.

Characteristics Frequency (n) Percentage (%)

Age (years)

Mean ± SD

9 ± 0.2

___

Gender

Female Male

107 98

51.4% 47.1%

Sequence of child

First-born Second-born Third-born Fourth-born Fifth-born Sixth-born

53 68 54 26 6 1

25.6% 32.9% 26.1% 12.1% 2.9% 0.5%

Parent’s highest educational level

Secondary TAFE Tertiary Post-graduate

28 108 53 19

13.5% 51.9% 25.5% 9.1%

In relation to the oral habits of the participants, 47 (22.6%) have reported to have

had carried out thumb-sucking habits (Table 4.2). Of those that reported thumb-

sucking, 29 (61.7%) had carried out the habit for 12 months or more, 11 (23.4%)

56

had carried out the habit for more than 6 months but less than 12 months, while

7 (14.9%) had carried out the habits for six months or less. A number of the

participants reporting thumb sucking (18 or 38.3%) had commenced this habit at

the age of six months, while 12 (25.5%) had commenced the habit at 12 months

and 13 (27.7%) commenced at the age two to five years.

A total of 88 (42.5%) participants have had mixed feeding between breastfeeding

and bottle-feeding, while 62 (30.0%) were exclusively breastfed and 57 (27.5%)

exclusively bottle-fed (Table 2). Furthermore, a total of 93 (44.7%) participants

have used a pacifier, while 49 (23.6%) participants had not displayed any non-

nutritive sucking behaviour. In addition, 31 (14.9%) participants have used both

pacifier and thumb-sucking while 24 (11.5%) used other objects as non-nutritive

sucking behaviours, and only 11 (5.2%) have used thumb-sucking exclusively.

Amongst the 208 participants, 32 (15.4%) had snoring issues during sleep, 36

(17.3%) had both snoring and mouth-breathing issues during their sleep, mouth-

breathing alone reported in 16 (7.7%) participants, six (2.9%) reported snoring

and sleep-apnoea, and four (1.9%) reported sleep-apnoea alone. With respect to

surgery, 27 (13.0%) reported tonsils and adenoids being removed, 12 (5.8%) had

only tonsils removed, 18 (8.6%) had grommet surgery, eight (3.8%) had grommet

and adenoid surgery and four (1.9%) had adenoid surgery. There were 188

(90.4%) of participants who had not had or were undergoing any orthodontic

treatment or intervention, while 20 (9.6%) were or have had some orthodontic

intervention carried out. The frequency of dental occlusion present in the sample

included 72 (35.5%) participants with an overbite, 49 (24.1%) had AOB, 23

57

(11.3%) had protrusion, six (3.0%) had a cross-bite and 53 (26.1%) had a normal

class I occlusion (Figure 4.1).

Table 4.2: Descriptive Statistics Summary of the variables and occurrence frequency in the sample population.

Characteristics Frequency (n) Percentage (%)

Oral Habits

Thumb-sucking Duration of thumb-sucking Age commenced thumb-sucking

≤6 months 6-12 months >12 months 6 months 12 months 2-5 years

47 Total 7 11 29 18 12 13

22.6% 14.9% 23.4% 61.7% 38.3% 25.5% 27.7%

Feeding modalities

Breastfed Bottle-fed Mixed-fed

62 57 88

30.0% 27.5% 42.5%

Sleeping issues

Mouth breathing Snoring Sleep apnoea Snoring & mouth breathing Snoring & sleep apnoea

16 32 4 36 6

7.7% 15.4% 1.9% 17.3% 2.9%

Surgical procedures

Adenoidectomy Tonsillectomy Grommets Adenoidectomy & tonsillectomy Adenoidectomy & grommets

4 12 18 27 8

1.9% 5.8% 8.6% 13% 3.8%

Orthodontic intervention (previous or current)

20 9.6%

Occlusion

Normal Angle’s Class I Protrusion cross-bite Overbite Anterior open bite

53 23 6 72 49

26.1% 11.3% 3.0% 35.5% 24.1%

58

Figure 4.1: Incidence of various bites in the sample population (centre), and prevalence of thumb sucking for bite cluster (green indicating there is no history of thumb sucking and red indicating a history of thumb sucking).

59

4.2 INFERENTIAL ANALYSIS

No statistically significant relationship was noted between the type of bite (normal,

cross-bite, protrusion, over bite or open bite) and the child’s age at presentation

(P=0.1786), the child’s gender (P=0.918) or whether the child had orthodontic

intervention (P=0.1217) (Table 3). A statistically significant correlation was noted

between the sequence a child was within their family structure (first born, second

born etc.) and type of bite (P=0.0109). Children born after the first child in a family

unit (second to sixth) were 5.2 times more likely to have an abnormal bite that a

first child. The second child demonstrated 6.8 times higher likelihood of having a

cross-bite compared to all other children. Children who were not first born

(second to sixth in their family sequence) were 2.3 times more likely than first

born children to develop an overbite or AOB, and 2.1 times more likely to

specifically develop an AOB (Table 4.3).

Table 4.3: Statistical relationship between variables and the type of bite. Item P value Odds ratio (OR)

For abnormal bite* Odds ratio (OR) for

anterior open bite or over bite

Age of child (years) 0.1786 - -

Gender (Male/Female) 0.918 - -

Sequence of child 0.0109 5.15 (2nd to 6th born) 2.3 (2nd to 6th born)

Schooling level of parent (Secondary/TAFE or Tertiary/Postgraduate)

<0.001 3.0 (Secondary/TAFE) 1.4 (Secondary/TAFE)

Thumb sucking <0.001 - 4.3

Duration of thumb-sucking (<6 months, 6-12 months, >12 months)

<0.001 5.15 (more than 6 months) -

Age of onset of thumb-sucking (<6 months, 6-12 months, >12 months, 2-5 years)

0.0334 - -

Feeding modalities (breast, bottle, mixed)

0.002 5.2 4.2

Non-nutritive sucking behaviours

<0.001 1.8 1.5

Sleeping issues (snoring, mouth-

<0.001 6.2 5.1

60

breathing, sleep apnoea

The need for surgical procedures (tonsillectomy, adenoidectomy, grommets)

<0.001 3.4 2.7

*Abnormal bite comprises all malocclusions assessed in this study (open-bite, deep bite, cross-bite and

protrusion)

A statistically significant difference was noted in bite against the parent’s level of

schooling (P<0.001) with a 3.0 odds ratio (OR) of developing an abnormal bite

for children whose parents’ highest level of schooling was Secondary/TAFE than

Tertiary/Postgraduate levels of education. More specifically, a 1.4 OR was

determined for developing a deep/open bite for children whose parents’ highest

level of schooling was Secondary/TAFE compared to the Tertiary/Postgraduate

levels of education.

Thumb sucking also demonstrated a statistically significant correlation with

abnormal bite (P<0.001) (Table 4.3). There were no cases of development of a

deep bite or open bite in the absence of thumb sucking. All reported cases of

thumb sucking reported an abnormal bite (either protrusion, deep bite or open

bite). Thumb sucking was 4.3 times more likely to lead to an over or open bite

than no thumb sucking. Indeed, the presence of thumb sucking was able to

predict the presence of a deep or open bite with a sensitivity of 97.9% although

the specificity of 51.9% indicates not all thumb suckers develop a deep or open

bite. While there were fewer cases of open bite, thumb sucking had a 44.4 times

higher probability of developing an open bite than for non-thumb suckers. The

sensitivity and specificity of thumb sucking in predicting open bite of 78.7% and

92.3% respectively supports a predictive relationship. The presence of thumb

sucking increased the risk of a protrusion by 2%, a deep bite by 19% and an open

bite by 78.7%.

61

Similarly, the duration of thumb sucking demonstrated a statistically significant

association with bite (P<0.001) (Table 4.3). No child with a duration of thumb

sucking less than six months developed an open bite. While all children who

reported thumb sucking developed a bite abnormality, a duration of thumb

sucking of more than six months saw 92.5% develop an open bite. The age at

which thumb sucking started also showed a statistically significant correlation

with bite (P=0.0334) with the earlier onset increasing risk for protrusion by 8.3%,

deep bite by 25.0% and open bite by 66.7%. 100% of children in whom thumb

sucking commenced between the ages of two to five years developed an open

bite.

With respect to feeding methods, a statistically significant correlation was

demonstrated with bite (P=0.002). Children who were bottle-fed were 1.9 times

more likely to have an open bite than children who were breastfed. Furthermore,

children who were fed with mixed-methods or were bottle-fed combined were

15.2 times more likely to have an open bite than breastfed children. Breast

feeding a child provides a protective effect for the development of abnormal bites

with an OR of developing an abnormal bite of 0.2 compared to an OR of 5.2 for

developing an abnormal bite for those that were bottle fed. More specifically,

bottle feeding had a 4.2 OR for developing a deep or open bite compared to

breast feeding.

Non-nutritive sucking behaviours demonstrated a statistically significant

relationship with abnormal bite (P<0.001). Use of a pacifier as opposed to no non-

nutritive sucking was associated with 1.8 OR for developing an abnormal bite, 1.5

62

specifically for a deep or open bite, but only 1.3 OR for open bite. When a pacifier

was used in combination with thumb sucking, however, the OR for developing a

deep or open bite was 15.1 and specifically for an open bite of 10.8.

Children who snored were 6.2 times more likely (OR) of having an abnormal bite

and 5.1 times more likely to have an open bite than those with no sleeping issues

(P<0.001) with 37.5% of children reporting an open bite also having snoring

issues during their sleep. Moreover, children who had snoring issues and were

also mouth-breathers were 19.3 times (OR) more likely to have an open bite than

children with no sleeping issues; 69.4% of children who had an open bite

displayed both snoring and mouth-breathing sleeping issues.

A statistically significant relationship was also noted between abnormal bite in

children and the need for surgery (P<0.001) (Table 4.3). Any surgery associated

with tonsils, adenoids or grommets had an OR for developing a bite abnormality

of 3.4 and deep or open bite of 2.7. Specifically surgery for tonsils and/or

adenoids has an OR for developing a deep or open bite of 6.2, and for open bite

specifically of 7.7.

4.3 MULTI-VARIATE ANALYSIS

Given the nature of the data is largely nominal rather than continuous, correlation

parameters and traditional multi-variate analysis is inappropriate. There is some

merit to principal component analysis using factor analysis to produce

eigenvalues with eigenvalues representing the relative contribution to total

variability of the dataset (Figure 4.2).

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Figure 4.2: Factor analysis and eigenvalues highlighting four or perhaps five key variables.

While this provides an insight into the cumulative effects of data, it does not

provide a deep insight into the interaction amongst variable. This is probably best

done with neural network analysis. The scree plot (Figure 4.3) suggests that there

are four main factors to consider. These factors present outcomes independently

and show a strong correlation with one another. Factors with eigenvalues of less

than 1.0 were not considered, as it may weaken the overall predictive power.

The scree plot is a procedure that is used to identify a number of factors to retain

in factor analysis which was proposed by Cattell (1966). The eigenvalues are

plotted against their ordinal numbers and an analysis is done to identify where a

break or a levelling of the slope of the plotted line takes place. Tabachnick and

Fidell (2001) referred to the break point to be the point where a line drawn through

the points changes direction. The number of factors is indicated by the number

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of error variance. An eigenvalue is the amount of variance that a particular

variable or component contributes to the total variance. This corresponds to the

equivalent number of variables that the component represents (Tabchnick and

Fidell, 2001).

Figure 4.3: Scree plot with eigenvalue cut-offs suggesting four principle values for deeper exploration.

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Excluding relationships amongst variables against the child’s bite outlined above,

no statistically significant differences or relationships were noted across variables

for the sequence the child was born in the family nor gender, (P > 0.05). Thumb

sucking was statistically higher for children whose parents had secondary or

tertiary as their highest level of education (P=0.0005) compared to TAFE and

post graduate with no thumb sucking reported amongst the latter population. The

type of feeding also has a statistically significant variation based on parents level

of schooling (P<0.001) with an OR of breast feeding of 8.2 for secondary levels

of education compared to all other levels (tertiary, TAFE, post graduate). The

highest likelihood of sleep issues was reported where TAFE was the highest level

of education and lowest for secondary education (P<0.001). Post graduate

education levels for parents had a statistically higher likelihood of surgery

(P<0.001).

Breastfed children were less likely to thumb suck (P<0.001) with a protective OR

of 0.12. Thumb sucking is 11.3 (OR) times more likely in the presence of sleep

issues (P<0.001) and 3.0 times (OR) in those who had surgery (P<0.001). The

age of onset and duration of thumb sucking were strongly associated with earlier

onset suggesting longer duration (P<0.001) although later onset with prolong

duration of thumb sucking being a significant predictor of open bite.

4.4 NEURAL ANALYSIS

4.4.1 Combined Deep Bite and Open Bite

A neural network was developed and trained using Neural Designer Software to

better understand the multi-variate relationship amongst variables. The bite was

converted to a binary outcome (target) of the child having and deep bite or open

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bite (yes) or having another type of bite (no). All other variables were classified

as input variables. A correlation matrix was produced and this identified

redundancy in the variables. That is, multiple variables that independently predict

the outcome, but which show a strong correlation with one another, may weaken

the overall predictive power because the eigenvalues are less than 1.0. Thus,

eliminating redundancy can identify principal components and minimise

predictive error. The strength of the logistic relationship between each input and

binary output was determined and ranked (Table 4.4). While key variables were

identified, no specific redundancy was determined.

Table 4.4: Neural analysis and rank of variables against the binary outcome.

Variable Deep Bite and Open Bite

Thumb Sucking 0.568

Sleep Issues 0.503

Surgery 0.393

Feeding Type 0.33

Duration of Sucking 0.254

Sequence 0.18

Non-nutritive sucking 0.174

Parents Level of School 0.135

Age 0.0968

Ortho 0.0626

Age of Habit 0.0497

Gender 0.0391

The quasi-Newton method is used as the training algorithm and is based on

Newton's method but does not require calculation of second derivatives. Instead,

the quasi-Newton method computes an approximation of the inverse Hessian at

each iteration of the algorithm, by only using gradient information. The final

architecture of the neural network can be written as 8:6:4:1 (Figure 4.4).

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Figure 4.4: The final architecture inclusive of eight variables and a binary outcome.

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A good way to evaluate the predictive efficacy of the model is to plot a ROC

(Receiver Operating Characteristic) curve. This predictive capability is measured

by calculating the area under curve (AUC) which in this model was 0.86. That is,

using these variables and the neural network provides identification of children

with a deep or open bite with 86% accuracy (Figure 4.5).

Figure 4.5: ROC plot with AUC of 0.86.

4.4.2 Open Bite Only

A similar neural network was developed and trained where the bite was converted

to a binary outcome (target) of the child having an open bite (yes) or having

another type of bite including deep bite (no). All other variables were classified

as input variables. A correlation matrix was produced and no redundancy

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detected. The strength of the logistic relationship between each input and binary

output was determined and ranked (Table 4.5). The neural network resulted in a

final architecture the same (Figure 4.4) but an AUC for the ROC of 1.0. That is,

for predicting open bite, an accuracy of 100% was achieved using calibrated

weightings for the input variables. This neural network is programmable in python

language and readily incorporated into a mobile (phone) app for risk assessment

for parents.

Table 4.5: Neural analysis and rank of variables against the binary outcome.

Variable Open Bite

Thumb Sucking 0.754

Duration of Sucking 0.574

Orthodontic intervention -0.474

Feeding Type 0.291

Parents Level of School 0.261

Sleep Issues 0.24

Age 0.183

Gender 0.177

Surgery 0.156

Non-nutritive sucking 0.128

Age of Habit 0.113

Sequence 0.0233

4.4.2.1 Method

The data was evaluated using an artificial neural network (Neural Network version

2.9.5). There were 15 input variables and a single binary output of reported open

bite or no reported open bite. Following logistic regression and principal

component analysis, 15 inputs were reduced to just 2; thumb sucking (0.754) and

duration of thumb sucking (0.574).

The network architecture included 2 scaling layer inputs, 2 hidden layers of 3 and

1 node respectively using a logistic activation function (Figures 4.6 and 4.7)

(defines the output of each node based on its input) for a single probabilistic layer

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(binary). The weighted squared error method was used to determine the loss

index. A Quasi-Newton training method was employed using gradient information

to estimate the inverse Hessian for each iteration of the algorithm (no second

derivatives). The loss function (0.531) associated with the training phase

estimates the error associated with the data the neural network observes. The

selection loss (0.307) is a measure of the neural networks agility; generalisability

to new data. This indicates the need to optimise the number of hidden layers /

iterations in the final architecture. The final training architecture identified 2

scaling layer inputs, 2 hidden layers of 1 node each and a single probabilistic

layer (binary).

Figure 4.6: Initial neural network architecture using only 2 inputs, 2 hidden layers of 2 and 1 nodes respectively, and a single binary output.

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Figure 4.7: The logistic activation function defines the output of each node based on its input for a single probabilistic layer.

4.4.2.2 Results

Figure 4.8: Final neural network architecture using only 2 inputs, 2 hidden layers of 1 node respectively, and a single binary output.

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A number of metrics can be employed to test the errors in the neural network.

The final architecture was evaluated using a number of tests (Table 6) indicating

robust validation. Using receiver operator characteristics (ROC) analysis

demonstrated an area under the curve of 0.889. This correlates with a sensitivity

of 77.8%% and specificity of 100% and this is reflected in the confusion matrix

(77.8% true positives, 100% true negatives, 22.2% false negative and 0% false

positive).

Table 4.6: Validation error tests for the final architecture.

Training Selection Testing

Mean squared error 0.165321 0.128456 0.0919856

Cross-entropy error 0.482252 0.410326 0.310291

Weighted squared error 0.723807 0.385368 0.367942

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CHAPTER FIVE

DISCUSSION

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The aetiology of malocclusion is linked to both hereditary and environmental

influences (Corruccini & Potter, 1980; Heimer et al., 2008; Peres, Barros, et al.,

2007; Vig & Fields, 2000). Environmental variables include tongue posture,

pacifier use, finger/thumb-sucking habits as well as other social determinant

factors (Chevitarese et al., 2003; Hebling et al., 2008). Genetic Influences include

formation and development of the orofacial structures (Corruccini & Potter, 1980).

In this study, AOB has been shown to have a very strong correlation between

both nutritive (feeding modalities) and non-nutritive (thumb-sucking, pacifier use)

sucking habits. The clinical interest to better understand the aetiology and early

diagnosis of AOB malocclusion lead to the construction of this study. There is a

need to take into consideration that AOB malocclusion may require professional

assistance to aid in cessation of unwanted, causative, behavioural habits in the

early stages of life. These may include counselling and/or orthodontic

interventions to name a few.

The logistics regression model used in this study allowed for distinct calculations

of OR values for the different variables associated and analysed. The results from

this study found a very strong association between thumb sucking, duration of

thumb sucking and AOB. Those who sucked their thumb had a distinct Odds

Ratio of 4.3 times more likely to develop an AOB or deep bite. Furthermore, those

who sucked their thumb for a duration of 6 months or longer, were 5 times more

likely to have an abnormal bite. It was also noted that the presence of pacifier

use did little in the causative effect on AOB unless combined with thumb-sucking

habits with an OR of 1.8 to lead to an abnormal bite and an OR of 1.5 to result in

AOB or deep bite. Sousa, Ribeiro, et al. (2014) outlined the link between duration

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of pacifier use and AOB, where a duration longer than 36 months resulted in a

larger prevalence of AOB. Other studies found a relationship between pacifier

sucking for a long period and AOB (Bishara et al., 2006; Peres, Barros, et al.,

2007) while this current study identified the thumb-sucking to be the more

significant influence to developing AOB.

Feeding modalities also yielded an OR of 5.2 of bottle-fed children to have an

abnormal bite and 4.2 specific to AOB and deep bite. This suggests that those

who were bottle-fed or mixed-fed were more likely to develop a malocclusion than

breastfed children. Romero et al. (2011) identified that the analysis of the

relationship between prevalence of AOB and breastfeeding outlined that

exclusive breastfeeding between six to 12 months, or breastfeeding beyond 12

months of age played a positive role in dental occlusion in contrast to the absence

of breastfeeding, where the best positive outcome was for a duration of longer

than 12 months. Furthermore, sleeping issues such as snoring and mouth-

breathing identified a causative link to AOB and all other malocclusions, with an

odds ratio of 6.2 developing an abnormal bite if they had snoring issues and 5.1

to develop AOB and deep bite.

5.1 DEMOGRAPHICS

The current study examined children aged seven to 12 (in their mixed dentition

stage) in a regional town, New South Wales, Australia. To the best of our

knowledge, this study may be the only study that had incorporated only the mixed

dentition stage in Australia. The majority of studies evaluated the prevalence and

effect of non-nutritive and nutritive sucking habits on AOB at the deciduous

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dentition stage in various parts of the world including South America, Asia and

Africa.

A study conducted in Brazil examined feeding and non-nutritive sucking habits

and open bite prevalence, the sample group employed individuals ranging from

three to 18 years of age with Downs’ Syndrome (Oliveira et al., 2010). It had

similar results to the current study, identifying that longer duration of bottle-

feeding or less than 6 months duration of breastfeeding had causative

associations with open bite and cross bite. Finger/thumb-sucking was only

associated with a posterior cross-bite for the sample population they employed

(Oliveira et al., 2010). The current study had also incorporated other variables,

such as onset of feeding for a bigger sample size.

Another study by Cozza, Baccetti, et al. (2005) evaluated sucking habits and

facial hyperdivergency as risk factors for AOB in the mixed dentition. They

concluded that thumb-sucking for a prolonged duration as well as hyperdivergent

facial characteristics influence the development of AOB in the mixed dentition.

The current study did not take into consideration growth patterns, instead it

exclusively analysed behavioural causative factors such as nutritive and non-

nutritive sucking habits, and is in agreement Cozza, Baccetti, et al. (2005) in that

thumb-sucking plays a significant role in the development of AOB malocclusion.

In a longitudinal study by Ovsenik, Farčnik, Korpar, and Verdenik (2007) revealed

how morphological and functional traits of malocclusion altered during growth and

development. The study results identified that in 50% of the children examined,

a morphological malocclusion severity score from mild to severe was noted at

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three years of age and increased towards the end of the mixed dentition stage.

With using other classification methods, this high prevalence was in agreement

with another study by Thilander et al. (2001).

According to several studies, gender did not have any effect on development of

AOB (Machado et al., 2014; Peres, De Oliveira Latorre., 2007; Sousa et al.,

2007). The current study is in agreement with this argument, showing equal

distribution of male and female in all the occlusions evaluated, with a P value of

0.918 for relationship between the type of occlusion and the child’s gender.

On the other hand, socioeconomic status was seen as a risk factor in the

development of AOB. Peres, De Oliveira Latorre, et al. (2007) suggested that

lower socioeconomic backgrounds to be determinants of malocclusions,

specifically AOB. Sousa, Pinto-Monteiro, et al. (2014) also agrees with this

conclusion.

In the present study, it was shown that children whose parents highest level of

education to be secondary schooling or TAFE (technical and further education

institutes) were more likely to develop a malocclusion, specifically AOB and deep

bite than the children whose parents highest level of education were either tertiary

or postgraduate. Although level of education may not necessarily shed light on

the economic status and average salary earnings of the participants’ families, it

remains to be a social determinant based on level of education rather than

income estimate.

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Some studies stated that there was no association between socioeconomic

conditions and AOB. They also suggest for further investigations due to the lack

of significant associations between socioeconomic status and AOB in previous

studies (Frazão, Narvai, Latorre, & Castellanos, 2004; Kharbanda et al., 1994).

On the other hand, Warren et al. (2000) discovered that the older mothers who

had a higher level of education were more likely to have children who did not

display non-nutritive sucking behaviours when compared to younger mothers

with a lower level of education. These findings were also established by Farsi et

al. (1997) and Paunio et al. (1993). A similar trait was found in, who identified

similar patterns in the association between pacifier use and the mother’s level of

education (Peres, De Oliveira Latorre, et al., 2007). In the present study, there

was no specifications as to who is required to complete the questionnaire as it

was available for both mothers, fathers and legal guardians. Despite that, similar

results are depicted in the present study, in that parents/guardians of a higher

education level were less likely to have children who presented with non-nutritive

sucking habits.

5.2 QUESTIONNAIRE

The questionnaire used in this study relied upon previous studies conducted on

assessing the prevalence and aetiology of AOB with minor modifications. In a

study by Charchut et al. (2003), questions on previous and current nutritive and

non-nutritive sucking habits were examined, as well as the child’s history of ear

disease, tonsil and adenoid removal. Furthermore, questions on age of onset and

duration of finger/thumb-sucking habits and/or pacifier use as well as questions

on feeding modalities were analysed.

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While another study used a questionnaire that was validated in a pilot study in

Brazil. Questions in this study included child demographics (age, gender, and

household income), feeding modalities, and non-nutritive sucking habits.

Moreover, this study conducted clinical examinations in the school setting of

children’s occlusions using a mouth mirror and dental probe, where they visually

inspected the child’s maximum ICP occlusion (Cardoso et al., 2014).

Another study analysed the length of time the children were exclusively breastfed.

Children were grouped into four groups based on the following question; those

who were never breastfed, those who breastfed for a duration shorter than six

months, those who breastfed between six to 12 months and a final group of those

who breastfed for more than 12 months. Further to these groups, questions on

non-nutritive sucking habits were also incorporated into the questionnaire

(Kobayashi et al., 2010).

A similar study concerning children aged three to six years, attending public

preschools in south-eastern Brazil had a questionnaire examining child’s

demographics (age, gender, and name) as well as method and duration of infant

feeding. Guardians were also asked if their child regularly sucked on pacifiers

and/or had developed finger or thumb-sucking habits (Romero et al., 2011).

A study by Jabbar, Bueno, Silva, Scavone-Junior, and Inês Ferreira (2011),

conducted a similar study using similar questions on feeding modalities, non-

nutritive sucking habits and demographics. It had also outlined exclusion criteria

similar to that of the current study such as exclusion of children with grossly

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decayed/missing anterior teeth, dental anomalies and cleft lip/palate or other

developmental anomalies. Similar to Cardoso et al. (2014), the study by Jabbar

et al. (2011) also involved conducting a clinical examination in the school

environment of children’s occlusions using a mouth mirror and dental probe and

disposable orthodontic rulers.

In the current study, the minor modifications involved including the sequence of

the child within their family household (first born, second born, third born, etc.…),

as well as the highest level of education of the parent completing the

questionnaire. Furthermore, due to the inability to conduct a clinical occlusal

assessment of the children involved, illustrations were included in the

questionnaire, with simple and clear instructions for parents/guardians to follow

and assess their child’s dental bite and then choose the illustration that best fits

the description.

5.3 PREVALENCE

According to literature, the prevalence of malocclusions ranges between 26.0%

to as high as 87.0% (Dhar, Jain, Van Dyke, & Kohli, 2007). The prevalence of

AOB has been inconsistently reported in the literature. In a study by Vasconcelos

et al. (2011), the prevalence was reported to be 32% in the deciduous dentition.

This was higher than the prevalence of AOB in the deciduous dentition reported

by Sousa et al., (2007), which was reported to be 20.6%, but lower than the study

by Peres, Barros, et al. (2007), as high as 46.2% prevalence of AOB reported

who evaluated the prevalence on children aged six years.

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Cozza, Baccetti et al., (2005) Cozza, Baccetti, et al. (2005) reported the

prevalence of AOB to be 18% in the mixed dentition. In the present study, which

assessed the prevalence of AOB in the mixed dentition obtained the prevalence

of AOB from the sample population to be in agreement with the study by Sousa

et al., (2007) with 24% from a sample of 208 participants. The variations in

reported prevalence is due to the sample size and the varying demographics as

well the dentition development stage of the participants.

It has been suggested that the prevalence of AOB declined with advancing age,

indicating self-correction, growth alterations and ceasing of harmful oral habits

(Vasconcelos et al., 2011). Furthermore, the prevalence of non-nutritive sucking

behaviours declined with increased age (Heimer et al., 2008). Some evidence

has revealed that the longer the period of non-nutritive sucking behaviours a child

experiences, the risk of malocclusion in the primary dentition increased (Warren,

Bishara, Steinbock, Yonezu, & Nowak, 2001)This outlines that AOB has the

ability to correct itself if habit ceased by the age of three years.

The results of the current study show that there was no statistical significance

between type of malocclusion or the child’s gender and age at time of research.

Literature have suggested that a significant number of AOB cases can be

reversed if non-nutritive habits ceased at an early age. A longitudinal study stated

that a period of 48 months or more of non-nutritive sucking habits was a risk factor

for AOB (Warren, Bishara, Steinbock, Yonezu & Nowak, 2001).

A study by Vasconcelos et al. (2011) reported the prevalence of AOB to be

significantly associated with feeding type and non-nutritive sucking behaviours,

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but did not have association with gender, age or family income. Similar findings

were described by Peres, Barros, et al. (2007). In this study, AOB was highly

associated with thumb-sucking and duration of thumb-sucking. There was no

significant relationship with gender or age which is in agreement with Peres,

Barros, et al. (2007) and Vasconcelos et al. (2011). In this present study,

participants whose parents’ highest level of schooling was Secondary or TAFE

were 1.4 times more likely to have either a deep bite or an AOB than those whose

parents highest level of schooling was tertiary or postgraduate.

Persistent non-nutritive sucking behaviours have been shown to lead to an

increased prevalence of AOB (Adair et al., 1995; Samir E. Bishara et al., 2006;

del Valle et al., 2006; Ovsenik, 2009; Peres, De Oliveira Latorre, et al., 2007;

Viggiano, Fasano, Monaco, & Strohmenger, 2004). Other factors such as

genetics and environmental influences can affect malocclusion such as AOB.

Studies carried out in North America (Adair et al., 1995) and Brazil (Zardetto et

al., 2002) showed prevalence to be 0% and 1%, respectively, for those without

history of non-nutritive sucking behaviours. In the current study, it was shown that

longer duration of non-nutritive sucking habits, particularly thumb-sucking was

significantly associated with development of AOB.

Other studies in India (Ganesh, Tandon, & Sajida, 2005) and in North America

(Bishara et al., 2006) have shown the prevalence of AOB to be 5.25% and 6.1%,

respectively, for participants who displayed no history of non-nutritive sucking

habits. This can suggest that other factors such as genetics, growth patterns, and

feeding modalities can all have influence in the development of AOB. In the

present study, children who were bottle-fed or mixed-fed had more tendencies to

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develop AOB than those who were breastfed. In addition, children whose parents

had lower levels of education were more likely to develop abnormal occlusions

such as AOB than those whose parents had higher levels of education.

It is complex to compare and contrast for prevalence of AOB between published

articles. This is due to the varying methods employed in different studies, as well

as age differences in the sample populations, examiner subjectivity, particular

objectives and different sample sizes and demographics (Ciuffolo et al., 2005;

Onyeaso, 2004; Silva & Kang, 2001; Thilander et al., 2001). A high number of

studies carried out examining the prevalence of AOB were carried out primarily

on the deciduous dentition, involving participants as young as 36 to 58 months of

age ( Baalack, 1971; Kobayashi et al., 2010; Svedmyr, 1979; Vasconcelos et al.,

2011; Warren et al., 2001).

In relation to deep bite, literature suggests that deep bite prevalence increases in

the mixed dentition (Klocke, Nanda, & Kahl-Nieke, 2002). A study by Worms et

al. (1971) reported self-correction of the AOB to take place from a seven to nine

year old to a 10 to 12 year old sample in 80% of cases. Another study stated that

a slight decrease in deep bite took place from 12 to 18 years (Bergersen, 1988).

In the study by Klocke et al. (2002) revealed an increase in deep bite in relation

to the open bite group of participants, leading to a positive deep bite at 12 years

of age. This suggests that there is a consistent pattern in development of deep

bite which is also consistent with other literature (Bergersen, 1988; Bishara &

Jakobsen, 1998).

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5.4 NON-NUTRITIVE SUCKING

According to Warren and Bishara (2002), non-nutritive sucking habits are

acceptable until the age of three years without causing changes to the orofacial

structures. Persistent habits beyond three years of age can significantly increase

the likelihood of developing undesirable occlusal traits and dental arch at the end

of the primary dentition phase. These prolonged sucking habits, in association

with tongue-thrust swallowing, can result in a mechanical obstruction for the

development of the permanent anterior teeth leading to alterations causing AOB

(Warren & Bishara, 2002).

Ovsenik et al. (2007) argued that sucking habits, even for a short duration, need

to be taken into consideration as having a direct effect on the developing

occlusion as well as an indirect effect due to an alteration in the swallowing

pattern. Based on data of previous studies as well as the current study, sucking

habits is a crucial aetiological factor in influencing the development of the AOB

and hence must be taken into consideration. Ovsenik et al. (2007) also outlined

that sucking habits was a major influence in development of malocclusions as

well as a causative factor seen at the end of the mixed dentition period.

Furthermore, the self-correction for some AOB’s during the transition from mixed

to permanent dentition can take place given the cessation of thumb-sucking

habits. Some more severe AOB’s, that sometimes extend to the terminal molar

region rarely self-corrects spontaneously and will often require invasive and

complex treatment measures (Sandler, Madahar, & Murra, 2011).

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A study by Bishara et al. (2006) noted that finger or thumb sucking was highly

associated with an increased overjet. This is not presented in the present study,

where 96% of children with an overjet (protrusion) did not suck their

fingers/thumb. The high prevalence of sucking habits (40%) by Vasconcelos et

al., (2011), was suggested to be due to socioeconomic status, where more

women were working which led to shorter periods of breastfeeding and thus non-

nutritive sucking habits development in infants. In the present study, it was shown

that children whose parents had lower levels of education were more likely to

develop non-nutritive sucking habits which led to development of malocclusion

characteristics.

Several studies have outlined the main causative factors for AOB were non-

nutritive sucking habits such as thumb and pacifier (Peres, Barros, et al., 2007;

Tornisiello Katz & Rosenblatt, 2005), while others argue that breathing patterns

also has influence on this malocclusion (Klocke et al., 2002). Some even suggest

skeletal patterns to be the main cause (Yousefzadeh, Shcherbatyy, King, Huang,

& Liu, 2010). Another study states the early weaning and dental caries to play a

big role in the development of AOB (Peres, Barros, et al., 2007). In the current

study, the major influences on AOB were identified to be thumb-sucking habits

and duration of thumb-sucking habits.

The high prevalence of AOB seen in the present study may suggest that non-

nutritive sucking habits may not have ceased at an early age suggesting the lack

of self-correction to take place. The results in the present study revealed that

100% of children who had commenced thumb-sucking between ages two to five

years had an AOB. Furthermore, the majority of children (61.7%) who carried out

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thumb-sucking had done it for a duration of 12 months or more. The children who

had an AOB were divided into 21.6% in the 6-12 months duration category while

78.4% in the 12 months of more duration category. There were 92.5% of children

with an open bite who had carried out thumb-sucking for a duration longer than 6

months.

The results are further confirmed by Hebling et al. (2008) who stated that despite

the oral habits being a risk factor in the development of malocclusions such as

AOB, it does not necessarily indicate that this will take place. It is thus, dependent

on intensity and duration of the non-nutritive sucking habits as well as the child’s

facial growth patterns that can lead to an AOB malocclusion. It is shown in the

statistics mentioned above of the current study, children with a longer duration

(12 months of more) of thumb-sucking were more likely to have an AOB than

those who had lower durations of the habits (6-12 months)

5.5 FEEDING MODALITIES

Previous literature have suggested that AOB be associated with non-nutritive

sucking behaviours as well as nutritive sucking behaviours in forms of bottle-

feeding (Bishara et al., 2006; Ganesh et al., 2005; Peres, De Oliveira Latorre, et

al., 2007). Results of the present study showed similar relationships. According

to our findings, children who were bottle-fed or mixed-fed were more likely to have

AOB than those who were breastfed. Bottle-fed participants were 1.9 times more

likely to have an open bite than those who were breastfed, and those who were

mixed-fed were 15.2 times more likely. Moreover, the majority of children in the

current study were either bottle-fed or mixed-fed than exclusively breastfed. The

high prevalence of this has been suggested to be due to the world’s

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industrialisation and modernisation, requiring females to participate in the labour

force, leading to a decreased rate of breastfeeding (Farsi et al., 1997). It has been

argued that factors such as the influence of breastfeeding on development of

AOB is difficult to assess, due to the need to separate these effects from that of

non-nutritive sucking behaviours (Warren & Bishara, 2002).

The World Health Organization recommends exclusive breastfeeding until 6

months of age. This is to reduce the prevalence of gastrointestinal infection and

weight deficit (Kramer & Kakuma, 2012; Organisation, 2011). Breastfeeding has

shown to have an effect on occlusion. Some studies have suggested that

malocclusion can result if infants were breastfed for a period of less than 12

months. It was noted that this may be due to the adoption of non-nutritive sucking

behaviours to fulfil natural sucking needs for comfort (Kobayashi et al., 2010;

Kramer et al., 2001; Narbutyte, Narbutyte, & Linkeviciene, 2013; Peres, Barros,

et al., 2007). Breastfeeding for a prolonged duration was suggested to have a

protective factor against malocclusion, specifically AOB (Sousa, Ribeiro, et al.,

2014). Furthermore, the WHO have also advised against artificial nipples such as

bottle-feeding and pacifier use, as it influences early weaning and development

of malocclusions (Vallenas & Savage, 1998).

It was noted that prolonged breastfeeding can exert a positive effect on the

development of deep bite in the deciduous dentition. This is through satisfying

the urge to suck as well as preventing the occurrence of non-nutritive sucking

habits and possibly stimulating correct tongue position and nose breathing

(Romero et al., 2011). Breastfeeding was concluded to have a protective factor,

stimulating the skeletal and muscular development of the child's face (Kobayashi

88

et al., 2010; Vasconcelos et al., 2011). In the present study, children who were

breast-fed showed tendencies towards normal occlusion development, while

those who were bottle-fed or mixed fed had tendencies to develop a deep bite,

protrusion and AOB. .

It is well established that prolonged durations of non-nutritive sucking habits lead

to malocclusions, specifically AOB in the primary dentition stage (Dos Santos et

al., 2012; Jabbar et al., 2011; Kobayashi et al., 2010; Oliveira et al., 2010;

Romero et al., 2011; Urzal, Braga, & Ferreira, 2013; Urzal et al., 2013;

Vasconcelos et al., 2011). Although, the effect of bottle-feeding remains to be a

controversial factor. Several studies not only suggest the link between the

development of malocclusions but also the type of occlusal alterations to be

associated with bottle-feeding (Charchut et al., 2003; Dos Santos et al., 2012;

Jabbar et al., 2011; Oliveira et al., 2010; Vasconcelos et al., 2011).

In the study by Oliveira et al. (2010) who evaluated the relationship between

determinants and prevalence of malocclusion in children with special needs

demonstrated that the children who had AOB or cross-bite were those whose

mothers stated bottle-feeding for a duration of 24 months or more. These findings

are also documented in the literature, establishing the link between bottle-feeding

and malocclusion (Góis et al., 2008).

It is suggested that the artificial nipples of the feeding bottles are made from a

more rigid material. This can influence the interior of the oral cavity, leading to

malocclusions of teeth and transverse growth of the palate. These are conditions

that results in the development of malocclusions such as posterior cross-bite

89

(Drane, 1996). In the present study, bottle-feeding and mixed-feeding were

shown to have an effect in the development of all malocclusions, however the risk

factors more closely linked to AOB were thumb-sucking and prolonged duration

of thumb-sucking.

5.6 SLEEPING ISSUES

Sleep-disordered breathing (SDB) in children is a very common as well as serious

health problem. This includes mouth-breathing, snoring, obstructive sleep-

apnoea (OSA) to mention a few. Surgical procedures to correct snoring, OSA and

mouth-breathing include tonsillectomy and adenoidectomy which are highly

recommended for paediatric patients, given that the child presents with enlarged

tonsils and/or adenoids (Sabuncuoglu, 2013). In the present study, children who

had snoring or mouth-breathing issues were more likely to develop abnormal

occlusions such as protrusion, deep bite and AOB. Furthermore, children who

had surgical procedures to remove tonsils and/or adenoids were children who

presented with deep bite, protrusion and AOB.

Furthermore, Li et al. (2010) noted that sufficient duration of breastfeeding had a

positive impact in reduction of the risk of habitual snoring in school-aged children.

It is suggested that children who were breastfed for duration of two to five months,

had reductions in sleep-disordered breathing (SDB) (Montgomery-Downs,

Crabtree, Capdevila, & Gozal, 2007). Longer than five months duration of

breastfeeding had little effect on SDB (Montgomery-Downs et al., 2007). In the

present study, children who were breastfed or mixed-fed were least likely to have

stated as having mouth-breathing, snoring or other sleep issues.

90

5.3 LIMITATIONS

A study that was carried out by Sousa, Ribeiro, et al. (2014), 78% of the sample

involved children aged three to four years old, while only 22% were five years old.

The prevalence of AOB in this study was calculated to be 21%. Age and

prolonged use of pacifier and/or thumb-sucking habits were strongly associated

with AOB. In contrast, a study by Ramos-Jorge, Motta, Marques, Paiva, and

Ramos-Jorge (2015), 50.6% of the sample involved children aged five years and

had a 69.9% prevalence of malocclusion in the anterior region. Similarly, there

was high association between non-nutritive sucking habits and AOB. This present

study analyses children in their mixed dentition stage, aged seven to 12 years of

age with a prevalence of 76% for AOB.

It has been suggested that with an increasing age, non-nutritive sucking habits

reduce, as well as parents’ understanding of their child’s limitations as they

mature, becomes simplified. Hence the sampling process identifies the

differences in the results amongst these studies in terms of prevalence of AOB

and non-nutritive sucking habits. It is, however not shown in the present study,

with a higher prevalence percentage than those mentioned above. This can

suggest a lack of cessation of undesirable habits, unfavourable growth factors

associated, varying demographics in terms of region and country. As has been

suggested previously that prolonged duration of non-nutritive sucking habits in

combination with a hyperdivergent facial pattern may lead to a significant risk

factor in AOB malocclusion (Urzal et al., 2013). Furthermore, the majority of

previous literature evaluated children from South America, particularly Brazil and

Venezuela. The difference in ethnicity can play a role in the prevalence rate

across various regions.

91

It is accepted that the tendency of self-correction of the AOB takes place from the

primary to the mixed dentition stage. This can only take place if cessation of

unfavourable habits such as pacifier use, and finger/thumb-sucking takes place

(Dimberg, Lennartsson, Söderfeldt, & Bondemark, 2011; Franco & Gorritxo,

2012; Urzal et al., 2013). Diagnosis of AOB is crucial, due to other dental

anomalies associated with it such as posterior cross-bite and tongue thrust. AOB

will self-correct given habit has ceased before the age of three years (Dimberg et

al., 2011). This will hence prevent structural and myofunctional deviations which

might sustain the morphological malocclusions (Ovsenik et al., 2007).

Educating parents/guardians at an earlier stage is therefore vital. This study also

confirms that for AOB to self-correct, cessation of non-nutritive sucking habits

need to take place. The high prevalence rate shown in the present study can

therefore suggest that there is a possibility the children sampled in the study who

presented with an AOB did not cease habits at an earlier age. Another limitation

includes not evaluating within the questionnaire whether or not the non-nutritive

sucking habit was current on the date the questionnaire was conducted.

Taking into consideration the use of bottle-feeding and its relation to pacifier

and/or thumb-sucking habits (Telles et al., 2009), it is advisable to introduce semi-

solid and solid foods into the child’s dietary intake as soon as the child develops

the primary dentition and has the capacity to perform masticatory movements

(Romero et al., 2011). The present study did not evaluate timeframe of when solid

food was introduced to the child during their infant years.

92

Although the present study is strong, it has some limitations. It was not possible

to compare the findings in this study with the result of similar investigations of the

primary dentition since the majority of studies exclusively investigated the

deciduous dentition, while this study analysed the mixed dentition. Furthermore,

other studies were qualitative in nature (Thilander et al., 2001; Tschill et al., 1997)

and the quantitative assessment of functional malocclusion traits as well as

associated factors were not taken into account. While this study evaluated the

quantitative component of the association between AOB and environmental

determinants such as non-nutritive sucking habits.

Population sample did not reach the targeted sample size and was extracted from

one public primary school in the region. In addition to that, due to ethics, it was

not possible to physically conduct a clinical occlusal assessment of the children

who participated in the study, suggesting that some potential inaccuracy could

have played a role in the influence of results. These include non-expert

assessment of occlusion by parents/guardians rather than a dental practitioner,

assessment using photographs rather than a clinical exam of the child, and

assessment of photographs that either represent the lateral or the frontal aspect

of the mouth and not the overall view of the mouth. Additional studies with

inclusion of a clinical occlusal exam, are required to outline the prevalence, clarify

the aetiology and identify the severity of AOB across different regions of Australia

to establish more descriptive data representative of the Australian population.

5.8 RECOMMENDATIONS

Future recommendations would be to include a larger sample population of

children from different schools (including public and private schools). This sample

93

size may include a bigger age range of children, perhaps assessing children that

are younger with only deciduous dentition to compare to the mixed dentition

stage. These results can then be comparable to studies conducted of deciduous

dentition in different parts of the world to evaluate the prevalence among the

Australian population and how it compares with Asian and South American

sample populations.

Additionally, assessing and comparing different parts of Australia, including

metropolitan, regional and rural demographics would provide results that can be

generalizable to the Australian population. Furthermore, it would be beneficial to

analyse and compare Indigenous children to non-Indigenous children which

would shed more insight on the prevalence and effect of non-nutritive sucking on

AOB that is more accurate and representative of the Australian population.

Another future recommendation includes obtaining ethical approval to carry out

expert assessment and measurements of children’s occlusion by a dental

practitioner which would yield more descriptive results. These could be assessed

by two orthodontic specialists where intra-rater and inter-rater reliability measures

may be conducted to yield more accurate data.

5.9 CONCLUSIONS

In sum, this study reported that the prevalence of AOB (76%) among children

with mixed dentition in Orange, NSW was generally higher than what has been

reported in other parts of the world, including South America and Asia. Insufficient

breastfeeding duration, prolonged duration of thumb-sucking with/without

combining pacifier use all had aetiological association with AOB with the major

94

contributor being over 12-months thumb-sucking commencing between 2 and 5

years of age. Furthermore, sleeping issues such as snoring and mouth-breathing

were highly associated with all malocclusions examined. Children whose parents

had selected secondary or TAFE as their highest level of education were more

likely to develop AOB than those whose parents were of tertiary or post-graduate

levels of education.

In conclusion, the findings of this study suggest the importance of early

awareness and education to parents on non-nutritive sucking behaviours and the

effects it can have on the growth and development of the orofacial structures

leading to abnormal malocclusions. This study can initiate future studies on

prevention and early treatment strategies to correct AOB caused by behavioural

factors.

95

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APPENDICES

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Appendix I. Information sheet to prospective parents/guardian and to child.

PARTICIPANT INFORMATION SHEET (Parent/Guardian)

Prevalence and determinants of Non-Nutritive Sucking on Anterior Open

Bite in Children Attending Primary School

Chief researcher:

Liyana Tanny

Postgraduate student and Oral Health Therapist

Project Supervisors:

o Professor Boyen Huang –Head of School, School of Dentistry and Health

Sciences, Charles Sturt University, President-elect of IADR Australian and

New Zealand Division

Expertise: Paediatric dentistry, and health care

administration

o Dr Geoffrey Currie – Associate Professor, School of Dentistry and Health

Sciences, Charles Sturt University

Expertise: Medical Radiation, clinical trial and statistics

o Dr Ashraf Shaweesh – Lecturer in Oral Health, School of Dentistry and

Health Sciences, Charles Sturt University

Expertise: Head and neck anatomy

Invitation

You are invited to participate in a research study on assessing prevalence and

effects of non-nutritive sucking on anterior open bite in children aged 7-12 years.

The study is being conducted by Liyana Tanny, an Oral Health Therapist and

current Postgraduate student in the School of Dentistry & Health Sciences at

Charles Sturt University.

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Before you decide whether or not you wish to participate in this study, it is

important for you to understand why the research is being done and what it will

involve. Please take the time to read the following information carefully and

discuss it with others if you wish.

1. What is the purpose of this study?

This project focuses on evaluating the prevalence of children with

finger/thumb sucking habits and how it may affect their teeth alignment

leading to a malfunction in the dental bite, known as a ‘anterior open bite’.

The project aims at identifying the individuals affected and educating

patients on their oral behaviours and attitudes as well as guiding them to

seek proper dental treatment where necessary.

Anterior open bite (AOB) describes the position where the front teeth don’t

contact during closure of the jaw causing individuals to have deficiencies

in function, speech, mastication and aesthetics. This leads to a term known

as malocclusion (abnormal bite), which is a term used to describe

abnormal contact of upper and lower teeth when the jaw is in closure.

There are several types of malocclusions, with AOB being one of the most

complex to diagnose and treat.

There is limited access for communities in regional and rural

demographics to dental services. In addition, treatment options available

in correcting the open bite are very costly and time consuming with lack of

public awareness by families of children affected in these regions. Hence,

carrying out this project will allow these families awareness in regional

communities on recognising and addressing this abnormal bite in children.

It is crucial for these children to have correct bite as it will impact on the

quality of their life. Individuals with anterior open bite experience

deficiencies in speech, mastication, function and aesthetics, thereby

impacting on their quality of life and self-esteem.

2. Why have I been invited to participate in this study?

We are seeking children aged 7-12 years and their families to participate

in this study. If you agree to participate in this study, you will be required

to fill out a simple questionnaire that should not take longer than 10

minutes to complete. The questionnaire can be handed back in its original

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envelope to your child’s teacher for collection by the researcher.

Information gathered from both questionnaire will assist dental

professionals to better manage and educate patients on importance of

contacts between teeth and its overall effects on the body.

3. What does this study involve?

If you agree to participate, you will be asked to fill out a simple

questionnaire about your child’s oral behaviours and their demographics

(age, gender, and sequence within the family household) as well as other

questions on medical conditions that may have an influence on alignment

of teeth.

4. Are there risks and benefits to me in taking part in this study?

No risks are associated with this study. All information collected will be

confidential. No personal information will be collected or published.

5. How is this study being paid for?

The research will be funded through the University with possible external

funding when approved.

6. Will taking part in this study cost me anything, and will I be paid?

Taking part in this study will not cost anything but no payments will be

made either. There is however, an oral health pack in the draw to win for

those who participate and wish to be a part of the draw.

7. What if I don’t want to take part in this study?

Participation in this research is entirely your choice. Only those people

who give their informed consent will be included in the project. Whether or

not you decide to participate, is your decision and will not disadvantage

you.

If you do decide to participate, and consent to your child participating, you

and your child may withdraw from the project at any time without giving a

reason and have the option of withdrawing any data, which identifies you.

8. What if I participate and want to withdraw later?

You have the right to withdraw from participation at any time and all

data/information collected will be returned to you.

9. How will my confidentiality be protected?

All data will be kept in a safe filing cabinet that is locked or in a computer

filed that has a password and only the investigators will have access to it.

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All data will be collected in a coded format and no personal information will

be identifiable by the researchers.

10. What will happen to the information that I give you?

All data will be presented in a coded/numerical format and will be as part

of a postgraduate thesis that will be published. No personal information

will be collected, disclosed or published.

11. What should I do if I want to discuss this study further before I

decide?

If you would like further information please contact Liyana Tanny on

0432033432.

12. Who should I contact if I have concerns about the conduct of this

study?

NOTE: Charles Sturt University’s Human Research Ethics Committee (for

low risk projects list the Faculty that approved the research) has approved

this project. If you have any complaints or reservations about the ethical

conduct of this project, you may contact the committee through the

Executive Officer:

The Executive Officer

Human Research Ethics Committee

Tel: (02) 6338 4628

Email: [email protected]

Any issues you raise will be treated in confidence and investigated fully

and you will be informed of the outcome.

Thank you for considering this invitation.

This information sheet is for you to keep.

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Appendix II. Consent Form

CONSENT FORM (Parent/Guardian)

Chief researcher:

Liyana Tanny

Postgraduate student and Oral Health Therapist

Project Supervisors:

o Professor Boyen Huang – Head of School, School of Dentistry and Health

Sciences, Charles Sturt University, President-elect of IADR Australian and

New Zealand Division

Expertise: Paediatric dentistry, and health care

administration

o Dr Geoffrey Currie – Associate Professor, School of Dentistry and Health

Sciences, Charles Sturt University

Expertise: Medical Radiation, clinical trial and statistics

o Dr Ashraf Shaweesh – Lecturer in Oral Health, School of Dentistry and

Health Sciences, Charles Sturt University

Expertise: Head and neck anatomy

I agree for my child to participate in the above research project and give my

consent freely.

I understand that the project will be conducted as described in the Information

Statement, a copy of which I have retained.

I understand that my child can withdraw from the project at any time and do not

have to give any reason for withdrawing.

I consent to

Filling out the questionnaire which will be analysed by the researchers

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The researchers accessing all information I disclose on the questionnaire

I understand that my personal information will remain confidential to the

researchers

I have had the opportunity to have questions answered to my satisfaction

Print Name:

_________________________________________________________

Signature______________________ Date: _________________

NOTE: Charles Sturt University’s Human Research Ethics Committee (for low

risk projects list the Faculty that approved the research) has approved this

project. If you have any complaints or reservations about the ethical conduct of

this project, you may contact the committee through the Executive Officer:

The Executive Officer

Human Research Ethics Committee

Tel: (02) 6338 4628

Email: [email protected]

Any issues you raise will be treated in confidence and investigated fully and you

will be informed of the outcome.

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Prevalence and determinants of Non-Nutritive Sucking on Anterior Open

Bite in Children Attending Primary School

CHANCE TO WIN AN ORAL HEALTH PACK

If you wish to go into the draw to win an oral health pack, please provide your

email address and return along with your questionnaire.

Email: __________________________________________________________

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Appendix III. Questionnaire

QUESTIONNAIRE

Number coding of Child: Date of Child Birth: /………/……….

Sequence of child amongst siblings:

1. Highest schooling level of Parent filling the form

Primary

Secondary

TAFE (Diploma/apprentice/certificate)

Tertiary (undergraduate)

Tertiary (postgraduate)

2. Is your child enrolled in a private or public primary school?

Private

Public

3. Has your child ever presented with finger/thumb-sucking habits? Circle

correct answer(s)

No

Yes:

o Less than 6 months duration

o 6 months duration

o More than 6 months duration

o More than 12 months duration

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4. Age of onset of thumb-sucking

6 months old

12 months old

2-5 years old

5. What form of feeding did your child experience as a baby? Please circle

the correct answer(s).

Breast-feeding

Bottle feeding

Mixed breast and bottle feeding

6. What form of non-nutritive sucking did your child used as a baby?

Please circle correct answer(s).

Pacifiers/dummies

Finger/thumb-sucking

Other objects/toys

None

7. Does your child have or had any sleeping problems, such as snoring,

mouth-breathing? Please circle correct answer(s)

No

Snoring

Mouth breathing

Sleep-apnoea

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8. Has your child ever had or was told to require to have surgeries for

tonsils, grommets or adenoids? Please circle correct answer(s)

No

Tonsils

Adenoids

Grommets

9. Has your child undergone or is undergoing any orthodontic treatment

(such as braces)?

Yes

No

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Appendix IV. Dental Occlusion illustration component of the questionnaire.

Normal bite

Under-bite

Protrusion (Overjet)

Overbite

123

Open-bite

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Appendix V. Letter to Schools

Letter of Information and Permission (Schools)

Prevalence and determinants of Non-Nutritive Sucking on Anterior Open

Bite in Children Attending Primary School

Chief researcher:

Liyana Tanny

Postgraduate student and Oral Health Therapist

Project Supervisors:

o Professor Boyen Huang – Head of School, School of Dentistry and Health

Sciences, Charles Sturt University, President-elect of IADR Australian and

New Zealand Division

Expertise: Paediatric dentistry, and health care

administration

o Dr Geoffrey Currie – Associate Professor, School of Dentistry and Health

Sciences, Charles Sturt University

Expertise: Medical Radiation, clinical trial and statistics

o Dr Ashraf Shaweesh – Lecturer in Oral Health, School of Dentistry and

Health Sciences, Charles Sturt University

Expertise: Head and neck anatomy

Invitation

You are invited to participate in a research study on assessing prevalence and

effects of non-nutritive sucking on anterior open bite in children attending your

school and aged 7 to 12 years.

The study is being conducted by Liyana Tanny, an Oral Health Therapist and

current Postgraduate student in the School of Dentistry & Health Sciences at

Charles Sturt University.

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Before you decide whether or not you wish to participate in this study, it is

important for you to understand why the research is being done and what it will

involve.

The study will involve providing a short questionnaire to parents/guardians of the

children attending the school between the ages 7 and 12, following providing

information on the study and gaining written consent. The questionnaire will

comprise questions regarding oral habits of children (such as thumb

sucking/pacifier use), social history (including breastfeeding/bottle-feeding) as

well as questions regarding medical conditions.

Anterior open bite (AOB) is a type of dental malocclusion (abnormal bite). It

describes the lack of contact between the upper and lower front teeth during

maximum closure of the jaw. AOB is one of the most difficult bites to treat

requiring much intervention and is hence very costly. Individuals with anterior

open bite have deficiencies in speech, chewing, swallowing and have a low self-

esteem affecting the quality of their life. In addition, AOB has a high relapse rate

even with orthodontic and surgical treatment.

This study will check the prevalence of children with anterior open bite.

Furthermore, it will evaluate the link between the abnormal bite and oral habits

(thumb-sucking/pacifier use). Through this, we can identify the abnormal bite

from an early age and provide early interventions or prevention to those affected.

I approve to let Ms Liyana Tanny approach and invite parents and students to

participate in this research project. I also approve to having children go through

a simple dental check-up during the school hours in the classroom with the

teacher present. I have had the opportunity to have questions answered to my

satisfaction

Principle name: ________________________________________

Signature_________________________ Date: _________________

NOTE: Charles Sturt University’s Human Research Ethics Committee (for low

risk projects list the Faculty that approved the research) has approved this

126

project. If you have any complaints or reservations about the ethical conduct of

this project, you may contact the committee through the Executive Officer:

The Executive Officer

Human Research Ethics Committee

Tel: (02) 6338 4628

Email: [email protected]

Any issues you raise will be treated in confidence and investigated fully and you

will be informed of the outcome.