Comparison of bone regeneration in alveolar bone of dogs on mineralized collagen grafts with two composition ratios of nano-hydroxyapatite and collagen

To study the effect of two composition ratios of nano-hydroxyapatite and collagen (NHAC) composites on repairing alveolar bone defect of dogs. Eighteen healthy adult dogs were randomly divided into three groups. Two kinds of the NHAC composites were prepared according to the constituent ratios of 3:7 and 5:5; immediately after extraction of the mandibular second premolars, each kind of the NHAC composite was implanted into extraction socket, respectively: Group I, nHA/Col = 3:7; Group II, nHA/Col = 5:5 and Group III, blank control group. The bone-repairing ability of the two grafts was separately analyzed by morphometric measurement, X-ray tomography examination and biomechanical analysis at 1st, 3rd and 6th month post-surgical, respectively. The NHAC composites were absorbed gradually after implanting into alveolar bone defect and were replaced by new bone. The ratios of new bone formation of Group I was significantly higher than that of Group II after 3 months (P < 0.05). The structure and bioactive performance can be improved when the ratio between the collagen and the hydroxyapatite was reasonable, and the repairing ability and effect in extraction sockets are obviously better.