Relationship of Maxillary First Molar Rotations with Malocclusions and Other Occlusal Variables

Abstract

The aim of our study was to determine the relationship between the rotation of maxillary first molars and various features of malocclusions. Initial models of 1237 patients were used for this study. Models were evaluated according to dental malocclusion, cross bite, crowding, rotation of upper incisors, canines and premolars, diastemas, and rotation of mandibular molars. 21.7 % of the models had a Class I, 64.8 % Class II, and 13.4 % Class III dental relationship. In Class III cases a significant increase in maxillary molar rotation was observed, followed by Class II and Class I maloclusions. There were increased second maxillary molar rotation values in Class III maloclusions, but no difference between Class II and Class I. Cases with cross bite, only upper crowding, both upper and lower crowding and rotated upper premolars had a significant increase in maxilary molar rotations. On the contrary, cases with canine and incisor rotations and diastemas had significantly less maxillary molar rotations. No relationship was found between mandibular molar rotations and maxillary molar rotations. Although higher rotational values could be expected in Class II malocclusions due to early migration of maxillary molars, the results of the present study support a stronger association with Class III malocclusions. As a result, during treatment planning, especially in Class III malocclusions, correction of molar rotations routinely should be listed as a treatment objective.

Keywords

• molar rotation
• malocclusions lusions