Diagnosis
Dental crossbite
A dental crossbite can occur with or without a skeletal discrepancy. For details see the detailed description.
Transverse skeletal discrepancies
Transverse skeletal discrepancies occur when the maxilla is narrow relative to the mandible. This can occur with or without a posterior dental crossbite. For details see the detailed description.
Dental crossbite associated with a functional shift
Mild dental or skeletal transverse discrepancies can lead to a mandibular functional displacement and a unilateral crossbite.
Aetiology of the posterior crossbite
Dental crossbites:
- Crowding, displacement of teeth, supernumeraries
- Soft tissue dysfunction e.g. habits like thumb sucking, lowered tongue position
- Airway disturbance (i.e. chronic nasal obstruction causing obligatory mouth-breathing)
Skeletal transverse discrepancies:
- Genetics (i.e. hypoplastic maxilla, Treacher Collins syndrome etc.)
- Airway disturbance (i.e. chronic nasal obstruction causing obligatory mouth-breathing)
- Congenital (i.e. cleft palate, Pierre Robin sequence)
Clinical Considerations
Treat the aetiology
- Treatment of posterior crossbites need to involve the management of its aetiology
- Over-compensating dental expansion to correct a skeletal transverse discrepancy will cause palatal cusp tipping or periodontal attachment loss on the buccal surfaces
- Not addressing the aetiology will also lead to increased relapse risks
High relapse risk
- Correction of posterior crossbites due to soft tissue dysfunction can have a high tendency of relapse if the soft tissues have not been corrected.
Earlier treatment is more predictable
- Orthopaedic expansion of the maxilla is best performed pre-pubertal when there is less interdigitation of the intermaxillary sutures
- Expansion performed at a pre-pubertal age has been shown to be more orthopaedic and more stable than those done at later age (Baccetti 2001, Lagravere 2005)
- Expansion performed at a pre-pubertal age has also been shown to deliver expansion more superior in the maxilla (i.e. in the nasal and zygomatic region). Care must be given to only use light forces in the skeletal immature patient as the inferior nasal septum (vomer) displacement can occur. (DeClerk and Proffit 2015)
