Influence of the extraction protocol of two maxillary premolars on the occlusal stability of Class II treatment

Objective: With the purpose of evaluating the influence of two upper premolar extraction on the occlusal stability of full cusp Class II malocclusion treatment, a comparison was performed with a non-extraction treatment protocol. Methods: To this end, a sample consisting of 59 patients with complete Class II malocclusion was selected from the files of the Department of Orthodontics of the Dental School of Bauru. This sample was split into two groups according to the following characteristics: Group 1 included 29 patients treated without extractions and Group 2 included 30 patients treated with the extraction of two upper premolars. Using the TPI and PAR occlusal indices the subjects’ study models were evaluated at the beginning and end of treatment, and at a minimum of 2.4 years after treatment. The occlusal conditions at the end of treatment and in the post-treatment period, the percentage of relapse and post-treatment occlusal changes were compared using Student’s t-test. Results: The results showed no statistically significant differences between the nonextraction and the extraction of two maxillary premolars treatment protocols in terms of the occlusal stability of complete Class II malocclusion treatment in any of the evaluated variables. Conclusions: The extraction of two upper premolars in the treatment of Class II malocclusion did not influence the stability of the occlusal results achieved at the end of the orthodontic treatment. Therefore, a similar stability is achieved by finishing a treatment with either a Class II or a Class I molar relationship.