Clinical investigation of periodontal ligament distraction osteogenesis for rapid orthodontic canine retraction.

Aims: To investigate rapid canine distalisation by periodontal ligament distraction and to determine the effects of periodontal ligament distraction on the canine root and pulpal vitality.

Methods: The sample consisted of 16 upper canines in eight patients who required first premolar extractions. The upper first premolars were extracted and the interseptal bone distal to each canine was thinned and undermined surgically. Custom-built distractors were placed and activated immediately to distract the canines into the extraction spaces. Radiographs were taken before canine distraction and at regular intervals thereafter. The upper canine pulps were tested with an electronic pulp tester before and after the distraction and the canines were examined on the post-distraction radiographs for evidence of apical and lateral root resorption.

Results: The canines were retracted to proximal contact with the second premolars in 20.33 +/- 1.87 days. The average amount of retraction was 5.25 mm and the canines tipped distally 15.33 degrees. Although the upper molars did not move mesially, they extruded almost 1 mm. Root resorption was minimal and there was no deterioration in pulp vitality.

Conclusion: Canines can be rapidly retracted by periodontal ligament distraction without complications. However, the efficacy of the method depends upon the surgical procedure, which is technique sensitive. Resistance offered by the interseptal bone distal to the apex of the canine was thought to be the reason for the canine tipping during distraction.