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Long-term stability of Class II malocclusion treated with 2- and 4-premolar extraction protocols
Guilherme Janson1, Vladimir Leon-Salazar, Ruben Leon-Salazar
1Department of Orthodontics, Bauru Dental School, University of São Paulo, Bauru, SP, Brazil. jansong@travelnet.com.br
Introduction:
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.
Methods:
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.
Results:
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.
Conclusions:
Treatment of complete Class II malocclusions with 2 maxillary premolar extractions or 4 premolar extractions had similar long-term posttreatment stability.
