Manegment and Etiology of Dental cross bite · 2018-08-18 · a-Primary/mixed dentitions An anterior crossbite in a child with baby teeth or mixed dentition may ha ppen due to either

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Ministry of higher Education

And scientific Research

Collage of maisan university

Department of dentistary

Gradution progect

Manegment and Etiology of Dental cross bite

APROGECT SUBMITTED TO THE MAISAN

UNIVERCITY COLLEGE DEPARTMENT OF DENTISTARY

IN PARTIAL FULFILLMENT OF THE REQUIRMENT FOR

THE B.SC IN DENTISTARY

BY:_

Tuqa saleem

Mareim radhi

Ban kareem

Supervised by:_

Salam raad abd alwahab

Younis mohemmed

D.h 1439 2018A.H

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Crossbite :_is a form of malocclusion where a tooth (or teeth) has a

More bucal or lingual position (that is, the tooth is either closer to the

cheek or to the tongue) than its corresponding antagonist tooth in the upp

er or lower dental arch. In other words or

crossbite:_ is a lateral misalignment of the dental arches.

Buccal crossbite: the buccal cusps of the lower teeth occlude buccal

to the buccal cusps of the upper teeth.

Lingual crossbite: the buccal cusps of the lower teeth occlude lingual

to the lingual cusps of the upper teeth. This is also known as a

scissors bite.

Aetiology

A variety of factors acting either singly or in combination can lead to the

development of a crossbite.

1 -Local causes

1-The most common local cause is crowding where one or two teeth are

displaced from the arch. For example, a crossbite of an upper lateral

incisor often arises owing to lack of space between the upper central incis

or and the deciduous canine, which forces the lateral incisor to erupt

palatally and in linguo-occlusion with the opposing teeth. Posteriorly,

early loss of a second deciduous molar in a crowded mouth may result in

forward movement of the upper fi rst permanent molar, forcing the second

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premolar to erupt palatally. Also

2- retention of a primary tooth can deflect the eruption of the permanent s

uccessor leading to a crossbite.

2 Skeletal:_ Generally, the greater the number of teeth in crossbite, the

greater is the skeletal component of the aetiology. A crossbite of the buccal

segments may be due purely to a mismatch in the relative width of the

arches, or to an anteroposterior discrepancy, which results in a wider

part of one arch occluding with a narrower part of the opposing jaw.

For this reason buccal crossbites of an entire buccal segment are most

commonly associated with Class III malocclusions_ and lingual

crossbites are associated with Class II malocclusions. Anterior

crossbites are associated with Class III skeletal patterns. Crossbites can

also be associated with true skeletal asymmetry and/or asymmetric

mandibular growth.

3-Soft tissues :_A posterior crossbite is often associated with a

digit-sucking habit, as the position of the tongue is lowered and a negative

pressure is generated intra-orally.

4 -Rarer causes:_ These include cleft lip and palate, where growth in t

he width of the upper arch is restrained by the scar tissue of the cleft repai

r. Trauma to, or pathology of, the temporomandibular joints can lead to re

striction of growth of the mandible on one side, leading to

asymmetryection.

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Types of cross bite:

1_Anterior crossbite:_

An anterior crossbite can be referred as negative overjet, and is typical of

class III skeletal relations (prognathism).

a-Primary/mixed dentitions

An anterior crossbite in a child with baby teeth or mixed dentition may ha

ppen due to either dental misalignment or skeletal misalignment. Dental

causes may be due to displacement of one or two teeth, where skeletal

causes involve either mandibular hyperplasia, maxillary hypoplasia or

combination of both.

b-Dental crossbite

An anterior crossbite due to dental component involves displacement of

either maxillary central or lateral incisors lingual to their original erupting

positions. This may happen due to delayed eruption of the primary teeth

leading to permanent teeth moving lingual to their primary predecessors.

This will lead to anterior crossbite where upon biting, upper teeth are

behind the lower front teeth and may involve few or all frontal incisors. In

this type of crossbite, the maxillary and mandibular proportions are

normal to each other and to the cranial base. Another reason that may lead

to a dental crossbite is crowding in the maxillary arch. Permanent teeth

will tend to erupt lingual to the primary teeth in presence of crowding.

Side-effects caused by dental crossbite can be increased recession on the

buccal of lower incisors and higher chance of inflammation in the same

area. Another term for an anterior crossbite due to dental interferences is

Pseudo Class III Crossbite or Malocclusion.

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c-Single tooth crossbite

Single tooth crossbites can occur due to uneruption of a primary teeth in a

timely manner which causes permanent tooth to erupt in a different

eruption pattern which is lingual to the primary tooth. Single tooth

crossbites are often fixed by using a finger-spring based appliances This

type of spring can be attached to a removable appliance which is used by

patient every day to correct the tooth position.

d-Skeletal crossbite

An anterior crossbite due to skeletal reasons will involve a deficient maxill

a and a more hyperplastic or overgrown mandible. People with this type of

crossbite will have dental compensation which involves proclined

maxillary incisors and retroclined mandibular incisors. A proper

diagnosis can be made by having a person bite into their centric relation

will show mandibular incisors ahead of the maxillary incisors, which will s

how the skeletal discrepancy between the two jaws

2-Posterior crossbite

Bjork defined posterior crossbite as a malocclusion where the buccal cusps

of canine, premolar and molar of upper teeth occlude lingually to the

buccal cusps of canine, premolar and molar of lower teeth. Posterior cross

bite is often correlated to a narrow maxilla and upper dental arch.

A posterior crossbite can be :_

1- unilateral

2- bilateral

3- single-tooth or entire segment crossbite.

Posterior crossbite has been reported to occur between 7–23% of the

population. The most common type of posterior crossbite to occur is the

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unilateral crossbite which occurs in 80% to 97% of the posterior crossbite

cases Posterior crossbites also occur most commonly in primary and

mixed dentition. This type of crossbite usually presents with a functional

shift of the mandible towards the side of the crossbite. Posterior crossbite

can occur due to: either skeletal, Dentalor functional abnormalities

One of the common reasons for development of posterior

Crossbite

* is the size difference between maxilla and mandible, where maxilla is

smaller than mandible Posterior crossbite can result due to

Upper Airway Obstruction where people with "adenoid faces" who have

trouble breathing through their nose. They have an open bite

malocclusion and present with development of posterior crossbite.

*Prolong digit or suckling habits which can lead to constriction of maxilla

posteriorly

*Prolong pacifier use (beyond age 4)

a--Unilateral posterior crossbite

Unilateral crossbite involves one side of the arch. The most common cause

of unilateral crossbite is a narrow maxillary dental arch. This can happen

due to habits such as digit sucking, prolonged use of pacifier or upper

airway obstruction. Due to the discrepancy between the maxillary and

mandibular arch, neuromuscular guidance of the mandible causes mandibl

e to shift towards the side of the crossbiteThis is also known as Functional

mandibular shift. This shift can become structural if left untreated for a

long time during growth, leading to skeletal asymmetries. Unilateral

crossbites can present with following features in a child

*Lower midline deviation to the crossbite side

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*Class 2 Subdivision relationships .

B_Bilateral buccal crossbite:_

Bilateral crossbites are more likely to be associated with a

skeletal discrepancy, either in the anteroposterior or transverse

dimension, or in both

C_ Bilateral lingual crossbite (scissors bite)

Again, this crossbite is typically associated with an underlying skeletal

discrepancy, often a Class II malocclusion with the upper arch further

forward relative to the lower so that the lower buccal teeth occlude with

a wider segment of the upper arch.

Crossbite Treatment

Achild with posterior crossbite should be treated immediately if the child

shifts his mandible on closing which is often seen in a unilateral crossbite

as mentioned above. The best age to treat a child with crossbite is in their

mixed dentition when their palatal sutures have not fused to each other.

Palatal expansion allows more space in an arch to relieve crowding and

correct posterior crossbite. The correction can include any type of palatal

expanders that will expand the palate which resolves the narrow

constriction of the maxilla.There are several therapies that can be used to

correct a posterior crossbite:

-braces

- 'Z' spring or cantilever spring,

- quad helix,-

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- removable plates, -clear aligner therapy

-or a Delaire mask.

The correct therapy should be decided by the orthodontist depending on

the type and severity of the crossbite.

One of the keys in diagnosing the anterior crossbite due to skeletal vs

dental causes is diagnosing a CR-CO shift in a patient. An adolescent presen

ting with anterior crossbite may be positioning their mandible forward

into centric occlusion (CO) due to the dental interferences. Thus finding

their occlusion in centric relation (CR) is key in diagnosis. For anterior

crossbite

- if their CO matches their CR then the patient truly has a skeletal compone

nt to their crossbite.

-If the CR shows a less severe class 3 malocclusion or teeth not in anterior

crossbite, this may mean that their anterior crossbite results due to dental

interferences.

* * Goal to treat unilateral crossbites should definitely include removal of

occlusal interferences and elimination of the functional shift. Treating

posterior crossbites early may help prevent the occurrence of

Temporomandibular joint pathology.

**Unilateral crossbites can also be diagnosed and treated properly by

using a Deprogramming splint. This splint has flat occlusal surface which

causes the muscles to deprogram themselves and establish new sensory

engrams. When the splint is removed, a proper centric relation bite can be

diagnosed from the bite.

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Self-correction

Literature states that very few crossbites tend to self-correct which often

justify the treatment approach of correcting these bites as early as

possible. Only 0–9% of crossbites self-correct. Lindner et al. reported that i

n a 50% of crossbites were corrected in 76 four year old children.

Treatment of anterior crossbite

The following factors should be considered.

• What type of movement is required? If bodily or apical movement is

required then fi xed appliances are indicated; however, if in the mixed

dentition tipping movements will suffi ce, a removable appliance can

be considered.

• How much overbite is expected at the end of treatment? For treatment

to be successful there must be some overbite present to retain the correctd

incisor position. However, when planning treatment it should be

remembered that proclination of an upper incisor will result in a reductin

of overbite compared with the pre-treatment position

• Is reciprocal movement of the opposing tooth/teeth required?

In the mixed dentition, provided that there is suffi cient overbite and

tilting movements will suffi ce, treatment can often be accomplished more

readily with a removable appliance. The appliance should incorporate

good anterior retention to counteract the displacing eff ect of the active

element (where two or more teeth are to be proclined, a screw appliance

may circumvent this problem) and buccal capping just thick enough to free

the occlusion with the opposing arch . Otherwise it may

be advisable to wait until the permanent dentition is established and

comprehensive fi xed appliance treatment can be carried out

. If there will be insufficient overbite to retain the corrected incisor(s),

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then consideration should be given to moving the lower incisors lingually

within the

confines of the soft tissue envelope in order to try and increase overbite.

If the upper arch is crowded, the upper lateral incisor often erupts in

a palatal position relative to the arch.

Treatment of posterior crossbite

Treatment in mixed dentition and perminent

It is important to consider the aetiology of this feature before embarking

on treatment. For example, is the crossbite due to

A_displacement of one tooth from the arch, in which case correction will

inolve aligning this tooth

-or is reciprocal movement of two or more opposing teeth

required? Also, if there is a skeletal component, will it be possible to

compensate for this by tooth movement? The inclination of the aff ected

teeth should also be evaluated. Upper arch expansion is more likely to

be stable if the teeth to be moved were initially tilted palatally.

Even when fixed appliances are used, expansion of the upper buccal

segment teeth will result in some tipping down of the palatal cusps

. This has the effect of hinging the mandible downwards leading

to an increase in lower face height, which may be undesirable in patients

who already have an increased lower facial height and/or reduced

overbite.

*If expansion is indicated in these patients, fixed appliances are

required to apply buccal root torque to the buccal segment teeth in order

to try and resist this tendency, perhaps with high-pull headgear as well.

Recent work has indicated that transverse problems which are amenable

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to orthodontic correction are best treated in the pre-pubertal

growth spurt. But the actual timing of treatment will depend upon other

features of the malocclusion.

As expansion will create additional space, it may be advisable to

defer a decision regarding extractions until after the expansion phase

has been completed.

b-Where a crossbite is due to skeletal asymmetry then a thorough

assessment is required to determine the aetiology and contribution of

both the maxilla and mandible to the presenting features. Correction

will require a combined approach involving orthognathic surgery once

growth has slowed to adult levels.

Interestingly, a Cochrane review on this topic reported that due to a

paucity of good quality evidence the authors were not able to make

recommendations

treatment of deciduous crossbit

*regarding treatment of crossbite in the mixed and permanent

dentitions. However, they did find that removal of premature

contacts in the deciduous dentition was eff ective in preventing posterior

crossbites being perpetuated into mixed/permanent dentition. Further

more, when grinding alone was not eff ective an URA could be used

to expand the upper arch to reduce the risk of the crossbite persisting.

Some typee of appliance used

1- The quadhelix appliance

The quadhelix is a very effi cient fi xed slow expansion appliance

. The quadhelix appliance can also be adjusted to give more

expansion anteriorly or posteriorly as required and can also be used to

de-rotate rotated molar teeth. When active expansion is complete it can

be made passive to aid retention of the expansion.

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A quadhelix is fabricated in 1 mm stainless steel wire and attached

to the teeth by bands cemented to a molar tooth on each side. Preformed

types are available which slot into palatal attachments welded

onto bands on the molars and can be readily removed by the operator

for adjustment. However, the appliance can also be custom-made in a

laboratory. The usual activation is about half a tooth width each side.

Over-expansion can occur readily if the appliance is overactivated, and

therefore its use should be limited to those who are experienced with

fi xed appliances.

*A tri-helix has only one anterior coil and is therefore less effi cient. Its

use is limited to cases with narrow and/or high palatal vaults, for example

in cleft lip and palate patients.

2- Rapid maxillary expansion (RME)

This upper appliance incorporates a Hyrax screw (similar to the type

used for expansion in removable appliances) soldered to bands, usually

to both a premolar and molar tooth on both sides. The screw is

turned twice daily, resulting in expansion of the order of 0.2–0.5 mm/

day, usually over an active treatment period of 2 weeks .

The large force generated is designed to open the midline suture

and expand the upper arch by skeletal expansion rather than by

movement of the teeth. For this reason some advocate limiting this

approach to patients in their early teens before the suture fuses, or

cleft palate patients where it can be utilized to expand the cleft segments

by stretching the scar tissue. If considering this approach it is

advisable to check that there is adequate buccal supporting bone and

soft tissues.

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Once expansion is complete the appliance is left in situ as a retainer,

usually for several months. Bony infi ll of the expanded suture has

been demonstrated but on removing the appliance approximately 50

percent of the expansion gained is lost, and for this reason some

overexpansion is indicated. This appliance should only be used by the

experienced clinician.

Surgically assisted RME (SARPE) is gaining acceptance, however

claims of reduced periodontal support loss (compared with conventional

expansion) and improved nasal airfl ow are unsubstantiated.

This approach involves surgically cutting the mid-palatal suture prior to

expansion

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REFFRENCE:_

CONTEMPORARY ORTHODONTICS(proffit 2013 )

TEXTBOOK OF ORTHONTICS (singh 2007 )

AN INTRODCTION TO ORTHODONTICS(michelle 2003 )

TEXTBOOK OF ORTHONTICS(foster 1990 )

ORTHODONTICS TREATMENT MECHANICS AND THE

PREADJUSTED APPLAINCE(BENNETT 1992 )