3D-tracking the regenerative potential of the mandible with micro-CTs.

Purpose: The treatment of large bone defects is a challenging problem especially when the mandible is affected. Bone healing is dependent on the defect size and the integrity of periosteum. So far, these both aspects have not been investigated separately. The aim of this study was to evaluate the healing potential of the mandibular bone with the help of three-dimensional micro-computed tomography (CT).

Methods: The angle of the mandible was exposed in 15 Wistar rats. A 3-mm core of bone was removed with a trephine. The local periosteum next to the defect was excised. Animals were randomized in five groups, which were ended 5, 10, 15, 28 and 56 days after operation. The mandible was excised and underwent micro-CT. For statistical evaluation, t-test statistics and regression analysis were applied.

Results: Characteristics of the defects began to change on the tenth postoperative day. Fifteen days until 4 weeks after intervention new mineralization processes could be observed. New bone grew from the borders into the defect. In the 2D study, bone apposition changed significantly from the beginning to week 8 (0.08 to 0.74 mm) as well as the 3D bone gain (0.05 % to 29.67 %) in t-test statistical evaluation. For development of the bone volume inside the defect linear as well as exponential regression analysis revealed a statistically significant connection.

Conclusions: This study quantified the amount of newly grown bone during osseous regeneration. We could show that the mandible itself provides regenerative capacity without any intact periosteum.