Effects of increased surgical trauma on rates of tooth movement and apical root resorption in foxhound dogs.

PURPOSE: To experimentally determine the effects of increased surgical trauma on the rates of tooth movement and apical root resorption. Two surgical techniques for rapid protraction of multi-rooted teeth in foxhound dogs immediately following premolar extraction were compared.
METHODS: Split-mouth design to randomly assign two surgical techniques [periodontal ligament distraction (RAP side) and a modified form of dentoalveolar distraction (RAP+ side)] to the maxillary quadrants. First premolars were extracted, and second premolars were protracted 0.5 mm per day for 15 days using a custom made jack-screw distractor. Serial caliper and radiographic measurements were performed to quantify tooth movements and apical root resorption.
RESULTS: Both techniques demonstrated significant movement of the crown and apex. The second premolar crowns were protracted significantly more on the RAP+ side (2.9 mm) than on the RAP (1.8 mm) side. The premolars on both sides demonstrated significant tipping (4.3 and 3.9 degrees for the RAP+ and RAP sides, respectively). The distal root apex showed almost twice as much apical root resorption than the mesial root apex, but resorption was limited (<0.16 mm) and not statistically different between sides.
CONCLUSIONS: Increased surgical trauma increased the rate and, ultimately, the amount of tooth movement. The heavy forces used to protract the teeth produced statistically, but not clinically, significant apical root resorption on the mesial and distal roots of the maxillary second premolars.