Long-term stability of Class II malocclusion treated with 2- and 4-premolar extraction protocols.Am J Orthod Dentofacial Orthop. 2009 Aug; 136(2):154.e1-10; discussion 154-5.AJ
The objective of this study was to cephalometrically compare the stability of complete Class II malocclusion treatment with 2 or 4 premolar extractions after a mean period of 9.35 years.
A sample of 57 records from patients with complete Class II malocclusion was selected and divided into 2 groups. Group 1 consisted of 30 patients with an initial mean age of 12.87 years treated with extraction of 2 maxillary premolars. Group 2 consisted of 27 patients with an initial mean age of 13.72 years treated with extraction of 4 premolars. T tests were used to compare the groups' initial cephalometric characteristics and posttreatment changes. Pearson correlation coefficients were calculated to determine the correlation between treatment and posttreatment dental-relationship changes.
During the posttreatment period, both groups had similar behavior, except that group 1 had a statistically greater maxillary forward displacement and a greater increase in the apical-base relationship than group 2. On the other hand, group 2 had a statistically greater molar-relationship relapse toward Class II. There were significant positive correlations between the amounts of treatment and posttreatment dentoalveolar-relationship changes.
Treatment of complete Class II malocclusions with 2 maxillary premolar extractions or 4 premolar extractions had similar long-term posttreatment stability.