The present study compared the number of erupted and functioning maxillary third molars and their mesio-distal angulation in patients with Class II malocclusions orthodontically treated with and without extraction of two maxillary premolars and fixed appliances. For that purpose, the records of 55 patients were selected, which were divided into two groups. Group 1 was treated without extractions and comprised 28 patient records (19 males and 9 females), with a mean age of 19.03 years [standard deviation (SD) = 2.33], treatment time of 2.59 years (SD = 1.08), and follow-up time of 6.48 years (SD = 2.42). Group 2 was treated with extractions and comprised 27 patient records (14 males and 13 females), with a mean age of 19.94 years (SD = 2.87), treatment time of 2.95 years (SD = 1.17), and follow-up time of 5.88 years (SD = 2.96). Analysis of the erupted and functioning maxillary third molars was conducted on the maxillary and mandibular dental casts. The mesio-distal angulations of the maxillary third molars were assessed on panoramic radiographs with the presence of both maxillary third molars. The results demonstrated that the number of erupted and functioning maxillary third molars was statistically greater (P = 0.01) in Class II subjects treated with extraction of maxillary premolars, when compared with those treated without extractions. The patients treated with two maxillary premolar extractions presented significantly smaller third molar mesio-distal angulations, that are more favourable to eruption, than those treated non-extraction.

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A professora Dra. REGINA MARIA PUPPIN RONTANI, coordenadora do Doutorado Interinstitucional, pela amizade, carinho e pelos conhecimentos transmitidos durante o programa de pós-graduação.Á CAPES pela oportunidade de realizar este curso de pós-graduação.