Orthodontic movement in bone defects filled with xenogenic graft: an experimental study in minipigs.

Introduction: In this study, we investigated whether it is possible to orthodontically move a tooth into an adjacent bone defect previously filled with xenogenic grafting material, with emphasis on the reactions of the tooth roots and adjacent tissues.

Methods: Six minipigs were used. In each animal, 4 defects were created at the mesial aspects of the maxillary and mandibular first permanent molars; the defects on the right were filled with the xenograft (test side), and the opposite defects (control side) were filled with blood clots and allowed to heal spontaneously. Three months later, orthodontic appliances were placed in each quadrant to allow mesial bodily movement of the first permanent molars. When the teeth were moved about halfway into the defect spaces, the animals were killed, and the areas of interest were harvested. The mesial roots of the first molars and adjacent tissues were histologically and morphometrically evaluated. The volume density of bone tissue, the percentage of root resorption, and the bone height were evaluated with image analysis software.

Results: Data analysis showed that (1) the percentage of root resorption was smaller (P = .0359) for the test group (4.16%) compared with the control (6.52%); (2) there was no statistically significant differences between groups concerning the volume density of neoformed bone (P >.05); (3) the bovine bone matrix was almost totally replaced by structured bone tissue; (4) the test group had a statistically significant smaller bone height loss (2.18 mm, P = .0018) than the control group (3.26 mm).

Conclusions: Based on these results, it was concluded that teeth can be moved into areas of bone defects previously filled with xenograft.