Treatment and posttreatment craniofacial changes after rapid maxillary expansion and facemask therapy

The aim of this study was to evaluate treatment and posttreatment dentoskeletal changes in 2 groups of subjects with Class III malocclusions. Subjects were treated with a bonded acrylic-splint expander and a face mask, and the optimal timing for this treatment protocol was assessed. The treated sample (29 subjects) was divided into 2 groups according to the stage of dental development. The early treatment group consisted of 16 subjects in the early mixed dentitional (erupting permanent incisors and/or first molars), whereas the late treatment group consisted of 13 subjects in the late mixed dentition (erupting permanent canines and premolars). Cephalograms were available at 3 time periods: T(1), pretreatment, T(2), end of active treatment, and T(3), posttreatment. The mean T(1)-T(2) interval (active treatment period) and the mean T(2)-T(3) interval (posttreatment period) were approximately 1 year each in both treatment groups. None of the patients wore any skeletal retention appliance during the posttreatment period (T(2)-T(3)). Groups of subjects with untreated Class III malocclusion were used as controls at both observation intervals. A significant increase in the sagittal growth of the maxilla was seen only when treatment was performed in the early mixed dentition. A restraining effect on mandibular growth rate associated with a more upward and forward direction of condylar growth was found in both treatment groups. An increase in vertical intermaxillary relationships was observed in Class III patients treated in the late mixed dentition. Posttreatment, the Class III craniofacial growth pattern was re-established in the absence of any skeletal retention appliance. Relapse tendency affects the sagittal growth of the maxilla in the early treated subjects and the sagittal position of the mandible in the late treated subjects. Orthopedic treatment of Class III malocclusion in the early mixed dentition is able to induce more favorable craniofacial adaptations than treatment in the late mixed dentition.