Maxillary Protraction In The Treatment Of Early Skeletal Class Ⅲ Malocclusion: A Primary Clinical Study

Skeletal Class III malocclusion is very common in clinic. Its clinical feature ismandibular protrusion and maxillary retraction. Especially, maxillary deficiency maylead to the concave of middle face, which tends to get worse with the growth. Thisdeficiency not only affects the function of stomatognathic system and facial aesthetics,but also impacts children’s mental health. Besides, the uncertainty of children’sgrowth makes the treatment of class Ⅲ malocclusion more difficult. Applyingmaxillary protraction can make maxillary basal bone grow forward and promote thegrowth of the maxilla. Therefore, before the pubertal peak, patients can be treatedwith maxillary protraction as orthopedic therapy. Maxillary protraction can stimulatethe growth potential and improve the unharmonious relationship between maxilla andmandible. Combined rapid maxillary expansion and maxillary protraction in thegrowing children is regarded as the main early corrective measure for Class IIImalocclusion, which could prevent the worsening of cross bite and could partiallyavoid orthodontic-orthognathic treatment in adults.Objectives：In this research, patients with skeletal Class III malocclusion marked bymaxillary deficiency were consecutively treated using rapid maxillary expansion andmaxillary protraction. The indexes of soft and skeletal tissues of maxillary inX-cephalometrics, which was taken pre-treatment, post-treatment and after6-month’sretention respectively, was compared and analyzed, in order to explore the clinical effect and stability of the combined therapy of palate expansion with maxillaryprotraction, and to provide effective evidence for clinical design and treatment.Methods：To chose18skeletal anterior crossbite patients from Department of Orthodontics,School of Stomatology XX, including8males and10females in the late mixeddentition. The ages ranged from8.5to13.5years, and the mean age was10.3years.For each patient, a lateral cephalogram was taken before treatment (T1), immediatelyafter treatment (T2), and an observation period (T3) averaging6months aftertreatment. All data was analyzed using anova.Results：All the patients were corrected from Class III to Class I.After the treatment, theA point (Subspinale) moved forward2.13mm(mean value) and SNA point increased0.92°(mean value) in T2. The maxillary teeth moved forward2.75mm (meanvalue)and the upper1-SN angle proclined5.01°(mean value). Meanwhile, all thepatients were corrected from reverse overjet to normal overjet. From-1.83-1.91.Themolar relationship was also corrected from Class III to Class I.The MPA grows from33.56to36.97, increase3.41. Y-axis increase0.86too. Both of them have statisticallysignificant.Assessment of the results demonstrated that skeletal tissue, soft tissue,theprofile and the posture of lips was improved. Some cases of the Class III correctionwere lost possibly because of mandibular growth.Conclusion：1.The treatment with combined rapid maxillary expansion and maxillary protraction totreat deciduous Class III,which improve the facial profiles, the skeletal tissue, softtissue, and the posture of the lips. We could conclude that it greatly reduced theprobability of orthognathic surgery when the patients become adults. 2. The effects of maxillary protraction were relatively stable. The relapses toClass III pattern was mainly because of mandibular growth.