Alveolar bone defects influence rate of tooth movement.

Objectives: To examine how defects in alveolar bone affect movement of teeth during orthodontic treatment. Materials and Methods: Pretreatment cone-beam computed tomography images from 26 patients: 15 females and 11 males, with a mean age of 21.5 years (SD ± 3.7 years), were used to evaluate the buccal alveolar bone on the maxillary canine. Maxillary canines (n = 52) were subsequently categorized into three groups: control or no bone defects (n = 17), fenestration (n = 20), and quasidefect (n = 15). Each canine was displaced distally for 16 weeks using nickel-titanium closed coil springs (50 g) and segmental archwire mechanics. The rate and amount of tooth movement were evaluated using superimposition of lateral cephalograms and three-dimensional digital dental models between before and after canine retraction. Rate of tooth movement was evaluated among different bone defect groups. Results: Rate of movement was significantly decreased in the fenestration (0.87 ± 0.23 mm/mo) and quasidefect groups (0.62 ± 0.14 mm/mo) compared to the control group (1.17 ± 0.40 mm/mo). Also, 85% of all subjects exhibited an evident asymmetric pattern of tooth movement, and 77% of these subjects presented with unilateral bone defects. Conclusions: The type and existence of alveolar bone defects have a substantial effect on rate of tooth movement. Therefore, when conducting orthodontic tooth movement investigations and planning orthodontic treatment, it is important to consider the existence of alveolar bone defects.