Orthodontic movement in bone defects augmented with Bio-Oss (R) - An experimental study in dogs

Objective: To study if it was possible to move, by orthodontic means, a too th into an area of the jaw that had been augmented with Bio-Oss(R). Material and Methods: 5 beagle dogs were used. The 1st, 2nd, and 4th mandib ular premolars on each side were removed. The defect at the left 4th premol ar site was filled with a biomaterial (Bio-Oss(R)) while the corresponding defect in the right side was left for spontaneous healing. 3 months later, an orthodontic device was inserted in each side of the mandible. The device was designed to allow distal, bodily movement of the 3rd premolars. When t he experimental teeth had been moved into the extraction sites of the 4th p remolars, the animals were sacrificed and biopsies of the premolar-molar re gions of the mandible sampled. The tissues were prepared for histological a nalysis using standard procedures. In the sections, 3 zones were identified : zone A = the bone tissue within the distal portion of the previous extrac tion site (4th premolar), zone B = the pressure side of the 3rd premolar, z one C = the tension side of the 3rd premolar. The area occupied by minerali zed bone, Bio-Oss(R) particles and bone marrow was determined by a point co unting procedure. The width of the periodontal ligament as well as the perc entage of the root surface (in zone B) that exhibited resorption was determ ined. Results: The findings demonstrated that it was possible to move a tooth int o an area of an alveolar ridge that 3 months previously had been augmented with a biomaterial. It was also demonstrated that 12 months after grafting, Bio-Oss(R) particles remained as inactive filler material in the not utili zed part of zone A. The biomaterial was not present in zone C but present i n small amounts in zone B. Conclusion: During the orthodontic tooth movement the graft material (Bio-O ss(R)) was degraded and eliminated from the part of the alveolar ridge that was utilized for the experiment. In the non-utilized part of the ridge the biomaterial, however, remained as a seemingly inactive filler material.