CROSS BITE Dr. JUNAID DAYAR

CROSS BITE

A discrepancy in the buccolingual relationship of the upper and lower teeth.

By convention the transverse relationship of the arches is described in terms of the position of the lower teeth relative to the upper teeth.

Lingual cross bite

The buccal cusps of the lower teeth occludebuccal to the buccal cusps of the upper

teeth

Buccal cross bite

the buccal cusps of the lower teeth occludelingual to the lingual cusps of the upper

teeth

Aetiology

Local causes Skeletal causes

Local /dental causes

The most common local cause is crowding where one or two teeth are displaced from the arch

early loss of a second deciduous molar causing a second premolar to erupt palatally/lingually

retention of a primary tooth can deflect the eruption of the permanent successor leading to a cross bite.

Skeletal crossbite

mismatch in the relative width of the arches e.g in thumb sucking, CLAP

Thumb sucking

Constriction of maxillary arch

Cross bite in clap

Skeletal crossbite

an anteroposterior discrepancy, which results in a wider part of one arch occluding with a narrower part of the opposing jaw e.g sk.cl II, sk cl III

Cross bite in skeletal classlII patient

Skeletal crossbite

Cross bites can also be associated with true skeletal asymmetry e.g trauma to TMJ, Hemifacial microsomia, Hemimandibular hypertrophy

Asymmetry and cross bite

Types of cross bite

Anterior cross bite Posterior cross bite

anterior crossbite

An anterior crossbite is present when one or more of the upper incisors is in linguo-occlusion (i .e. in reverse overjet) relative to the lower arch

Anterior crossbites are frequently associated with displacement on closure

Posterior cross bites

Cross bites of the premolar and molar region involving one or two teeth or an entire buccal segment.

can be subdivided as follows.1) Unilateral buccal crossbite with

displacement2) Unilateral buccal crossbite with no

displacement3) Bilateral buccal crossbite4) Unilateral lingual crossbite5) Bilateral lingual crossbite (scissors bite)

Unilateral buccal crossbite with displacement

deflecting contact on closure into the cross bite.

can affect only one or two teeth (dental) maxillary arch is of ”similar width” to the mandibular arch (i.e. it is too narrow) with

the result that on closure the buccal segment teeth meet cusp to cusp. In order to achieve a more comfortable and efficient intercuspation, the patient displaces their mandible to the left or right

Unilateral buccal crossbite with no displacement

less common Can be dental/ skeletal

Bilateral buccal crossbite

more likely to be associated with a skeletal discrepancy, either in the

anteroposterior or transverse dimension, or in both.

Unilateral lingual crossbite

This type of crossbite is most commonly due to displacement of an individual tooth as a result of crowding or retention of the deciduous predecessor

Bilateral lingual crossbite (scissors bite)

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

Scissors bite

How to differentiate b/w skeletal and dental cross bite

P.A cephalogram

Treatment of anterior cross bite (dental)

A developing cross bite can be managed by:

1) Tongue blade therapy2) Lower Inclined plane therapy3) Posterior bite block

Tongue blade therapy

CATALANS APPLIANCE OR LOWERANTERIOR INCLINED PLANE

Treatment of anterior cross bite (dental)

A.C.B which ha s already developed can be treated by:

1)Double cantilever spring with posterior bite plane

2)Fixed appliance(2 x4)

Double cantilever spring or 'Z' spring

2x4 appliance

Treatment of anterior cross bite (skeletal)

Maxillary expansion Proclination of upper and retoclination of

lower anterior teeth by fixed appliance (class III camouflage)

Facemask therapy Orthognathic suregry to correct the jaw

at fault

Appliance for anterior maxillary expansion

Correction of anterior cross bite with a fixed appliance

Face mask therapy

Treatment of posterior crossbite (dental)

Cross elastics fixed appliance

Cross elastics

Fixed appliance

Treatment of posterior crossbite (skeletal)

Eliminate sucking habits Remove any tooth interferences Maxillary expansion (rapid/slow) Orthognathic surgery

Tongue crib/habit breaking appliance

Tooth interference leading to cross bite

Max expansion using quadhelix

Quadhelix on cast

Max expansion using banded expander (hyrax expansion screw)

split –plate expansion appliance (Schwartz plate.)

Rapid Palatal Expansion

Done in adolescents and adults where strong interdigitation of suture is present

This creates 10 to 20 pounds of pressure across the suture-enough to create microfractures of interdigitating bone spicules

rate of 0.5 to I mm/day 2 to 3 week The expansion device is left in place for 3 to

4 months new bone forms in the space at the suture, and the skeletal expansion is stable

Bonded expander

Slow Palatal Expansion

Done in preadolescent children esp with cleft

2 pounds of pressure 0.5 mm-1mm per week damage and hemorrhage at the suture

are minimized expansion is completed in 2 to 3 months

Correction of cross bite with orthognathic surgery