Crossbites are classed as a buccolingual discrepancy between the relationship of the maxillary arch and mandibular arch.

The three following features should be taken into consideration when describing a crossbite:

• Anterior/posterior?
• Buccal/lingual?
  • Buccal crossbite – Buccal cusps of the mandibular teeth occlude lingual to the
    lingual cusps of the upper teeth
  • Lingual crossbite – Buccal cusps of the mandibular teeth occlude buccal to the buccal cusps of the maxillary teeth
• Bilateral/unilateral?

Anterior Cross Bite Treatment Options:

1. Fixed inclined bite planes

2. Removable appliances with bite plane and a spring or screw to procline the incisor

3. Fixed appliance bonded to anterior teeth and primary molars, first permanent molars or premolars

Posterior Cross Bite Treatment Options:

1. Elastics to correct single molar cross bites

2. Palatal expansion:

• Fixed appliance:
  • Quadhelix– efficient fixed slow expansion appliance, usual activation is 1cm on each side posteriorly and 1.5cm anteriorly.
  • Rapid maxillary expander– has a screw similar to removable appliances except it is soldered to bands on molars on both sides. The screw is turned twice daily over an active treatment period of two weeks

3. Removable appliances e.g. Hawley appliance with a jackscrew

NOTE: Best age to treat a child with cross-bite is in their mixed dentition when their palatal sutures have not fused to each other.