Clinical study of treatment for Class III malocclusion in mixed dentition

Objective To investigate the treatment method of Class Ⅲ malocclusion in mixed dentition.MethodsThirty patients with Class Ⅲ malocclusion in mixed dentition were selected and divided into two groups according to ANB angle measured on the cephalograms,Removable appliance group(0°ANB2°)and combined treatment group(-2°ANB0°).At the initiation of the therapy,the two groups were both treated with modified removable appliance to correct anterior crossbite.The combined treatment group then continued with maxillary protractor.The results were analyzed statistically before and after treatment.Results Mandibular functional shift factor was removed in the two groups treated with removable appliance.The SNA increased by 0.5° 5.2 months after treatment in the removable appliance group.After two years follow-up,relapse was noted in two patients.In the combined treatment group,the SNA increased by 0.5° after treatment with removable appliance for 5.4 months,and normal overbite and overjet of anterior teeth and ClassⅠmolar relationship were achieved after continued treatment with maxillary protraction for 5.6 months,and SNA increased by 1.65°,the concave profile of patients was improved and no relapse occured after two years follow-up.Conclusion To achieve good results,appropriate treatment design should be carefully chosen for patients with Class Ⅲ malocclusion in the mixed dentition.