A comparison of the effect of different occlusal

INTRODUCTION

A comparison of the effect of differentocclusal forms in mandibular implantoverdentures

Mohamed Moataz et.al .

University of Pittsburgh Medical Center, PittsburghJournal of Prosthetic Dentistry1 998;79:422-9

Posterior tooth form selection for implant overdentures

is made according to personal preference and

experience using the concepts of conventional

complete denture Prosthodontics.

STATEMENT OF PROBLEM

(1) Compared the masticatory efficiency of three

occlusal forms, 0 degrees, 30 degrees, and lingual

contact (lingualized occlusion), in subjects with

mandibular implant overdentures,

(2) Determined their effects on the implant supporting

tissues.

PURPOSE.

MATERIAL AND METHODS

INCLUSION CRITERIA

2. Skeletal class I jaw relationships.

3. Four root form endosseous-type implants (Nobel

Biocare, Göteborg, Sweden) in the mandibular

symphysis area that had been restored with Hader bar

retained implant overdentures and that had been in

function for at least 1 year before the study.

1. Eight edentulous subjects, four men and four women,

ages 52 to 78 years.

For each patient, a mandibular implant overdenture and a

maxillary conventional complete denture were constructed

both with interchangeable posterior occlusal segments.

(A posterior occlusal form was randomly selected for

each patient)

A, Maxillary and mandibular anterior teeth were set according to esthetics and

phonetics and were not changed throughout study.

B, Cross-section of maxillary and mandibular bases before attaching

different posterior

tooth forms.C, Zero degree posterior teeth attached to denture bases.

D, Lingualized posterior occlusion. Maxillary lingual cusps of posterior teeth

touch

central fossa of mandibular teeth.E, Use of 30 degree posterior segments

Patients used each occlusal form for 6 months during which

time three test sessions were performed at 2- month

intervals.

IN EACH TEST SESSION, PATIENTS’ MASTICATORY

EFFICIENCY WAS EVALUATED AND PERI-IMPLANT

MUCOSA AND BONE ASSESSED CLINICALLY AND

RADIOGRAPHICALLY.

Masticatory efficiency was evaluated through five measures

recorded while patients were chewing standardized pieces

(1 cm cubes) of test foods in normal manner.

The test foods used were bread, hard cheese, beef sausage,

raw carrots, and apples.

Patients were seated in an upright position and were

instructed to chew at a normal rate and swallow.

Four trials (four cubes) were made for each test food.

While chewing the food specimens, five measurements

were recorded:

a) The number of chewing strokes up to the first

swallow.b) The number of chewing strokes until the mouth was

free of food.

c) The number of swallows until the mouth was free of

food.d) The time (in seconds) elapsed until the first

swallow.

e) The time (in seconds) until the mouth was free of food.

(two persons who remained the same ,One recorded the number of

chewing strokes and swallows, and the other recorded the time.)

Patients’ chewing preferences were assessed with a

standardized questionnaire administered to patients

once every 6 months at the end of use for each posterior

occlusal form.(The questionnaire evaluated the patients’ opinion concerning

comfort during rest and chewing, stability, speech, ease of

cleaning, and appearance (esthetics) of their dentures.)

CLINICAL EVALUATION OF THE PERI-IMPLANT TISSUES

1. Plaque Index.

2. Gingival Index.

3. Mobility .

4. Probing Depth.

5. Measurement Of The Epithelial Attachment Level.

6. Changes in bone level around the necks of implants

was assessed with standardized periapical radiographs

with a superimposed grid.

7. Bone density along the length of the implants

was also

determined to detect minor bone changes.(The second and third randomly selected occlusal forms were

similarly tested every 2 months for 6 months.)

STATISTICAL ANALYSES

1. The mean chewing efficiency and clinical and

radiographic differences between the occlusal forms

were evaluated by a repeated measures analysis of

variance (MANOVA).2. Repeated measures analysis of variance (ANOVA) was

used to analyze self-report questionnaire data.

All analyses were computed with the SYSTAT

(Version 7)

p value of < 0.05 was considered to be

statistically significant

RESULTS

OCCLUSAL FORM MEAN ANALYSES

PATIENTS SUBJECTIVE OCCLUSAL FORM RATING

57.14% of patients preferred

the 30 degree occlusal form

42.86% preferred the

lingualized occlusal form.

None of the patients selected

the 0 degree occlusal form

RADIOGRAPHIC FINDINGS

CLINICAL FINDINGS

DISCUSSION

The primary results of this study showed that 30 degree

and lingualized occlusal forms provide better chewing

efficiency than 0 degree occlusal form in implant

overdentures.

The use of implants to stabilize and retain mandibular

dentures therefore improved denture retention and

stability closer to natural dentition than the removable

denture condition.

The values of the chewing efficiency measures also varied

significantly with the type of food used. Patients therefore

chewed and swallowed differently depending on the

hardness and texture of the food.Validation of methods for the analysis of masticatory

function. J Dent Res 1990;69:334.

Chewing efficiency and state of dentition. A methodologic

study. Acta Odontol Scand 1978;36:33-41.

The influence of food type on experimental design in studies of

chewing efficiency. J Dent Res 1991;70:277.

Radiographic assessment of the bone surrounding the

implants did not show any significant difference in height

or density associated with the different occlusal forms

used.

Lingualized and 30 degree occlusal forms had

significantly less gingival index scores compared with the

0 degree occlusal form.

CONCLUSIONS

1. The choice of posterior occlusal forms in implant

overdentures should not be based on conventional

complete denture occlusion.2. The number of chewing strokes up to the first swallow

and until the mouth was free of food provided better

discrimination between the different occlusal forms than

the chewing time and number of swallows.

4. The use of 30 degree and lingualized occlusal forms

provided better chewing efficiency than 0 degree occlusal

form.

NONE OF THE OCCLUSAL FORMS TESTED SHOWED ANY CLINICAL

OR RADIOGRAPHIC DETRIMENTAL CHANGES IN IMPLANT

SUPPORTING TISSUES