RESUMEN
PURPOSE: To investigate the influence of maxillary protraction combined with maxillary molar distalization appliance therapy on skeletal Class III cross bite malocclusion. METHODS: 60 patients with cross bite and crowding malocclusion were treated with maxillary protraction combined with maxillary molar distalization appliance. The arch length was analyzed before wearing appliance (T1), after debonding appliance(T2), and one year after debonding appliance(T3). SPSS10.0 software package was used for ANOVA. RESULTS: Before therapy, the maxillary arch length was not enough with arch length discrepancy. After active treatment, the device had extended the length of the upper dental arch significantly to relieve crowding and change the cross bite. Esthetics were greatly enhanced. CONCLUSIONS: Maxillary protraction combined with maxillary molar distalization appliance therapy change the maxillary arch length. However, further study is necessary to understand the long-term clinical effect.