crossbites Flashcards
what is the definition of a cross bite?
A Crossbite is apparent when the buccal cusps of the lower teeth occlude lateral to the buccal cusps of the upper teeth.
what is the difference between a buccal cross bite and a lingual cross bite?
> Buccal crossbite: buccal cusps of mandibular teeth occlude buccal to the buccal cusps of the maxillary teeth
> Lingual crossbite (scissors bite): buccal cusps of mandibular teeth occlude lingual to the lingual cusps of the maxillary teeth
what is the definition of displacement?
> any deflection occurring on closing from RCP into ICP demonstrated by a deviation in the mandible in the transverse or A-P plane to achieve maximum interdigitation
what is the prevalence of crossbites?
> Affects 8-22% of the population
> 10% of orthodontic patients
> only 2% are bilateral
> 3 times more common in pre-normal occlusions (Class III)
what are the classifications of crossbites?
- Unilateral buccal crossbite
- with displacement
- without displacement
- Bilateral buccal crossbite
- Unilateral lingual crossbite
- Bilateral lingual crossbite (scissors bite)
what are bilateral crossbites often associated with?
> always skeletal in origin
> often combined with a skeletal III
> treatment should be approached with caution, may cause cusp to cusp
what causes a unilateral crossbite without displacement?
> due to a true asymmetry of the skeletal bases, usually pathological in origin
> this could be due to cleft palate or condylar hyperplasia (condyle grows excessively on one side)
what is the aetiology of a cross bite?
- Hereditary factors … skeletal
- Environmental factors =
i. Digit sucking ii. Mouth breathing
are transverse anomalies bento alveolar or skeletal?
> Transverse anomalies like A-P anomalies can be dentoalveolar or skeletal or a combination of both
> accurate diagnosis is important for effective and stable treatment
why do we treat cross bites?
> Some evidence that displacing contacts may predispose a susceptible individual to TMD.
> Although this evidence is weak, a crossbite with a displacement is therefore a functional indication for orthodontic treatment.
> Preparation for bone grafting in patients with CLP.
which crossbites should we treat?
> NOT unilateral or bilateral crossbites without displacement.
> The malocclusion is of minor importance.
> There is a considerable tendency towards relapse – up to 40% with all for, sof active expansion
what was an old recommendation of treatment for child with a cross bite?
> Some recommend Grinding away cusps =
- To eliminate the displacing contacts.
- To facilitate spontaneous correction
N.B. But NOT recommended! as subjecting young child to invasive treatment that might not work and may suffer from hypodontia, this can also impact cooperation
what are the conflicting views in treatment of crossbites in the mixed dentition?
> NO – Leighton (1986) – spontaneous
correction frequently occurs.
> YES – Schroder (1981) & Petren (2003) – high
frequency of transmittance to
permanent dentition.
what is the general consensus in treatment of cross bite in a mixed dentition?
> Do not burn up patient co-operation as they will often require further tx
> Best with quadhelix.
> Consider leaving until later definitive Rx.
what is used for treatment of a dentoalveolar crossbite?
> Upper Removable Appliance
> Quadhelix
> Fixed appliances
