Experimental Effects of Alveolar Corticotomies on Tooth Movements

Objectives: A split-mouth design was used to experimentally evaluate (1) if and how much corticotomies increase tooth movements, and (2) the effects of a second corticotomy on the rate of tooth movement. Methods: Mandibular 3rd and maxillary 2nd premolars of five skeletally mature fox hound dogs were extracted. One randomly selected mandibular quadrant had buccal and lingual corticotomies performed around the 2nd premolar while the other quadrant served as the control; both maxillary quadrants had initial buccal corticotomies and one randomly selected quadrant had a second buccal corticotomy performed after 28 days. Sentalloy coil springs delivering a 200g force were used to move the mandibular 2nd and maxillary 3rd premolars on a 0.040mm guiding wire placed in a .045mm buccal tube. Records, including digital caliper measurements and radiographs, were taken at days 0, 10, 14, 28, 42 and 56. Multilevel statistical procedures were used to model longitudinal tooth movements. Results: Radiographic measurements showed mandibular tooth movement rates increasing initially, peaking between 22 and 25 days, and then decelerating. Total mandibular tooth movements were significantly (p<.05) greater on the experimental (2.4mm) than control (1.3mm) sides. Rates of maxillary tooth movements decreased regularly over time, with slightly, but significantly, greater movements with two (2.3mm) than one (2.0mm) corticotomy. Conclusions: Alveolar corticotomies significantly increase rates of tooth movements when orthodontic forces are applied to the teeth. Performing a second corticotomy after four weeks maintains higher velocities over a longer duration and produces greater tooth movements than performing just one initial corticotomy, but the differences are small.