Long-term stability of rapid maxillary expansion combined with chincup protraction followed by fixed appliances

Objective: To analyze the long-term stability of rapid maxillary expansion (RME) and protraction from chincup therapy in girls with Class Ill malocclusion. Materials and Methods: Twenty-two girls (mean age = 9.1 +/- 0.6 years) with Class Ill malocclusion were treated with combined RME and protraction from a chincup, followed by fixed appliances. Lateral cephalograms were evaluated before treatment, at the end of a two-phase treatment protocol (mean age = 15.1 +/- 1.1 years), and 10.9 +/- 0.5 years after the end of treatment (mean age = 27.5 +/- 0.5 years). The control group consisted of 22 matched girls with skeletal Class I malocclusion. Results: After treatment, the Class Ill group showed significant improvement of the Class Ill malocclusion, mainly due to changes in the mandible (ie, SNB angle decreased 1.8 +/- 1.6 degrees) and significant improvement of the sagittal maxillomandibular relationship (Wits appraisal increased 2.6 +/- 2.1 mm; ANB angle increased 1.0 +/- 0.3 mm). These changes remained stable for an average of 10 years after the end of therapy. No tendency toward relapse was detected, and the mandibular position showed favorable outcomes. Conclusions: RME and protraction from chincup therapy led to successful long-term outcomes in 18 of 22 patients (81.8%). This treatment approach can be considered an efficient therapy in growing girls with mild skeletal Class III malocclusion caused by maxillary retrusion and mandibular protrusion.