Mandibular Asymmetry And Condylar Position In Patients With Unilateral Posterior Crossbite

Posterior crossbites is one of the most frequently occurring malocclusion. Most of them are unilateral posterior crossbites. In patients with functional unilateral posterior crossbites, the mandibular shifts laterally toward the crossbites side on closure from opening to maximum intercuspation, often as a result of poor interdigitation and occlusion interference. That may develop into musculoskeletal problems, leading to a functional disturbance.Posterior crossbites, if left untreated, will usually persist from childhood into adulthood, the proposition has been made that untreated crossbite lead to growth alterations resulting in asymmetry on dentition, skeletal remodeling of the temporo-mandibular joints and facial asymmetry. But whether there is a definitive relationship between malocclusion and mandibular asymmetry is still unknown.In this study, patients with unilateral posterior crossbite were as sample andcompare with patients exhibiting nomalocclusion. The present study used SMV radiographs to evaluate asymmetry in the mandibular dentoalveolar or skeletal regions that might be associate with unilateral posterior crossbite. The study consists of three parts:1. Mandibular asymmetry and condylar position in children with unilateral posterior crossbite.The sample consists of 26 children with unilateral posterior crossbite. 28 children with nomalocclusion were as the control. The result showed that: Relative to the cranial floor coordinate system, the mandible in the unilateral posterior crossbite group exhibited significant asymmetry both in the anteroposterior as well as transverse dimension. The asymmetries were probably the result of a functional deviation of the mandible. With referencee to the mandibular coordinate system, no skeletal asymmetry of the mandible was found in the crossbite group. Children with UPCB have asymmetry condylar position in centric occlusion.2. Mandibular asymmetry and condylar position in adults with unilateral posterior crossbite.The sample consists of 21 adults with unilateral posterior crossbite. 23 adults with nomalocclusion were as the control. The result showed that: Relative to the cranial floor coordinate system, the mandible in the unilateral posterior crossbite group exhibited significant asymmetry both in the anteroposterior as well as transverse dimension. The present study found that the mandible in adults with unilateral posterior crossbite was "rotated" when related to the cranial floor, and its dentoalveolar segment was asymmetry. There was no demonstrable mandibular skeletal asymmetry in the unilateral posterior crossbite group.3. The effects of unilateral posterior crossbite to growth and development of mandibular and condylar.-6-The sample consists of 26 children with unilateral posterior crossbite. 21 adults with unilateral posterior crossbite were as the control. The result showed that: Relative to both the cranial floor coordinate system and the mandibular coordinate system, none of the skeletal variables were found to be sianificant between the groups. So the belief that untreated unilateral posterior crossbite lead to skeletal asymmetry of the mandibular was not supported by this study. The remodeling changes took place in condylar head in response to unilateral posterior crossbite.