INTRODUCTION: Palatal expanders have been advocated for spontaneous correction of some Class II malocclusions. However, little research has been done to determine whether correction or improvement actually occurs with expansion. Past research has not shown whether an anterior functional shift is achieved in patients who have Class II improvement. The objective of this study was to determine whether maxillary expansion causes spontaneous correction or improvement of a Class II malocclusion. METHODS: This was a retrospective study of subjects from an orthodontic office in which models are mounted (articulator) in centric occlusion and maximum intercuspation before and after treatment. The sample included Class II patients (n = 13; mean age, 10 years 3 months) who, during the preceding 2 years, had been treated with expansion alone. Study models made before and after expansion were measured to compare the centric occlusion to the maximum intersuspation position. Condyle position indicator paper was also used to determine whether there was a functional shift after expansion. RESULTS: The only measurements with statistically significant changes from pretreatment to postexpansion were the maxillary intermolar widths. Seven of the 13 patients showed Class II improvement, but none had an anterior functional shift after expansion. CONCLUSIONS: Maxillary expansion does not predictably improve Class II dental relationships. 2010 American Association of Orthodontists. Published by Mosby, Inc. All rights reserved.
INTRODUCTION: Palatal expanders have been advocated for spontaneous correction of some Class II malocclusions. However, little research has been done to determine whether correction or improvement actually occurs with expansion. Past research has not shown whether an anterior functional shift is achieved in patients who have Class II improvement. The objective of this study was to determine whether maxillary expansion causes spontaneous correction or improvement of a Class II malocclusion. METHODS: This was a retrospective study of subjects from an orthodontic office in which models are mounted (articulator) in centric occlusion and maximum intercuspation before and after treatment. The sample included Class II patients (n = 13; mean age, 10 years 3 months) who, during the preceding 2 years, had been treated with expansion alone. Study models made before and after expansion were measured to compare the centric occlusion to the maximum intersuspation position. Condyle position indicator paper was also used to determine whether there was a functional shift after expansion. RESULTS: The only measurements with statistically significant changes from pretreatment to postexpansion were the maxillary intermolar widths. Seven of the 13 patients showed Class II improvement, but none had an anterior functional shift after expansion. CONCLUSIONS: Maxillary expansion does not predictably improve Class II dental relationships. 2010 American Association of Orthodontists. Published by Mosby, Inc. All rights reserved.