The Clinical Study Of Early Functional Mandible Deviation Corrected By Maxillary Quad-Helix Expansion

Unilateral posterior crossbite(UPXB) is one of the most frequently occurring malocclusion in the mixed and early permanent dentitions.At the early stages,such crossbites are associated with a lateral shift of the mandible in approsimately 80% of cases and deviating arch midline.Some scholars deem that early UPXB mostly belongs to functional mandible deviation and correction of it through maxillary expansion is associated with a good change in mandible deviation. UPXB is used to be treated with rapid palatal expansion and slow expansion(Quad-Helix) in clinic.Although rapid palatal expansion might have provided a possible treatment solution,it was not used because,due to the patient's young age,some degree of skeletal influence could be expected after slow expansion.This study adopted slow expansion. Slow palate expansion makes bone suture grow more physiologically than rapid one . It can also maintain better integrality of longitudinal suture of palate and more stability in rebuilding maxillary complex.Objective To confirm that the correction of early posterior crossbite through maxillary slow expansion is associated with changes in functional mandible deviation. Then evaluating in detail the morphologic and functional effect of the treatment for this malocclusion category was to be appled this method to orthodontics thoroughly in order to increase treatment level.