Class II treatment success rate in 2- and 4-premolar extraction protocols.

This study compared the occlusal success rate of Class II orthodontic treatment results with either 2- or 4-premolar extraction protocols. Group 1 comprised dental study models of 81 patients treated with 2 premolar extractions, and group 2 comprised dental study models of 50 patients treated with 4 premolar extractions. The initial mean ages of the groups were 13.9 and 12.9 years, respectively. Grainger's treatment priority index (TPI) was used to assess the initial and final occlusal status of each patient. Individual variables, such as maxillary canine anteroposterior positioning, overjet, and overbite improvements were also evaluated. Independent t tests were used to compare the variables at the pretreatment and posttreatment stages and their improvement between the groups. The results showed a statistically significant difference in most of the variables and in their improvement at the end of treatment between the groups. The variables showed a better dental relationship in group 1, and the improvements in group 1 were larger than in group 2. Treatment of Class II malocclusion with 2 premolar extractions gives a better occlusal success rate than treatment with 4 premolar extractions.