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Duke Oral Health

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DSPD Safety Protocol

Posterior Crossbites


Posterior crossbite is a reverse bite in the back teeth on one or both sides of the mouth.  Normally top teeth fit on the outside of the bottom teeth – in a crossbite, the opposite is true.


A posterior crossbite is usually the result of constriction of the top jaw.  Constriction usually occurs from an active thumb habit, although there are many cases in which a cross bite is from an unknown origin.


The importance of correcting a crossbite ensures proper alignment and bite of the teeth.  An incorrect bite can lead to wear spots, a crooked smile, and malocclusion. If not corrected the permanent teeth will also likely erupt into a cross bite.


Expansion of the upper jaw is needed to correct the crossbite.  An appliance called a quad helix can slowly expand the upper jaw to correct the crossbite.  Two bands with a small wire are fit on the back molars.  This appliance is glued in and cannot be removed by the patient.  Usually the crossbite is corrected in approximately 6-8 months with a 4-6 month retention time afterwards.  There is no discomfort experienced during this expansion.