Three-dimensional evaluation of molar buccolingual inclinations after orthodontic treatment using edgewise mechanics

The purpose of this study was to measure changes in buccolingual inclination and in thickness of maxillary and mandibular buccal and lingual bone of maxillary and mandibular molars following orthodontic treatment using edgewise mechanics.

Cone-beam computed tomography scans of 48 patients taken before and after completion of comprehensive orthodontic treatment were collected for this retrospective study. Buccolingual molar inclinations were reported as angular measurements using the long axis of the teeth and inferior border of the nasal floor and inferior border of the mandible, respectively. Distances between the buccal and lingual cusps of maxillary and mandibular molars, respectively, were measured to the occlusal plane to assess the change in buccolingual inclination after orthodontic treatment. The amount of buccal and lingual bone at the level of the root apex of each molar was also evaluated before and after orthodontic treatment.

Orthodontic edgewise mechanics caused significant increases in mandibular first molars' inclination angle, lingual bone, and mandibular second molars' buccal bone and inclination angle. Significant decreases were noted in mandibular first molars' buccal bone, inclination distance and mandibular second molars' lingual bone and inclination distance. Maxillary teeth had fewer significant changes than the mandibular teeth. Significant decreases were found for maxillary first molars' buccal bone, inclination distance, and maxillary second molar buccal bone.