Stability of Class II treatment with two premolar extraction protocols

Even though posttreatment stability is one of the main goals of the orthodontic treatment, it is one of the most challenging outcomes to be obtained. Objective: To assess the stability of Class II treatment with two and four premolar extraction protocols. Methods: A total of 60 patients were selected who initially had full Class II malocclusions treated with fixed appliances. Thirty patients (17 male, 13 female) with an initial mean age of 12.87 years were treated with 2 premolar extraction (group 1), and 30 patients (14 male, 16 female) with an initial mean age of 13.64 years were treated with 4 premolar extraction (group 2). Lateral cephalograms were obtained at T1 (pretreatment), T2 (posttreatment) and T3 (9.42 years postretention). Independent t test was used to compare the groups in each stage and the treatment and posttreatment changes. Results: In T3 there was a greater recurrence of superior incisive teeth protrusion and molar relationship in the group treated with extractions of four premolars. It was also found that vertical growth pattern, decreasing of SNB angle, and the recurrence of the maxillomandibular relationship correction presented a significant correlation with the molar relationship relapse. In addition, the relapse of the overjet, overbite and canine relationship showed a direct correlation with the amount of their correction in both groups. Conclusion: Although the postretention changes were similar in both groups, there was a greater relapse tendency in the group 2. This study was supported by FAPESP process #04/12444-1.