[Effects of nicotine on alveolar bone loss in experimental periodontitis in rat: a micro-computed tomographic analysis].

Objective: To establish the three-dimensional images of rat's alveolar bone and to evaluate the effects of nicotine on alveolar bone loss during the process of ligature-induced periodontitis with micro-computed tomography (micro-CT).

Methods: Thirty-six adult male SD rats received silk ligatures around the cervix of the right second maxillary molars. Then the animals were randomly assigned to three groups and received daily intraperitoneal injections as follows: group A (control), saline solution; group B, nicotine, 0.83 mg x kg(-1) x d(-1); and group C, nicotine, 1.67 mg x kg(-1) x d(-1). Six animals in each group were randomly selected and sacrificed at day 14 and 28. Micro-CT examinations were used to evaluate the periodontal breakdown.

Results: With the nicotine dose increased, bone mineral density (BMD), bone volume fraction (BVF), and trabecular thickness (TT) gradually reduced, while the trabecular spacing (TS) and alveolar bone loss (ABL) increased. At day 28, the ABL of group C (left, right) was (0.61 +/- 0.14) mm and (1.39 +/- 0.09) mm, and significantly higher than that of group B [(0.39 +/- 0.10) mm and (1.31 +/- 0.06) mm] and group A[(0.30 +/- 0.06) mm and (0.94 +/- 0.07) mm]. The BMD of group C, group B and group A at day 28 was [(617.86 +/- 34.27), (572.46 +/- 31.62) mg/cm3], [(660.04 +/- 36.73), (604.97 +/- 32.59) mg/cm3] and [(709.15 +/- 34.95), (657.04 +/- 30.06) mg/cm3] respectively.

Conclusions: Daily administration of nicotine results in significant bone loss and microstructure deteriorations in the trabeculae of alveolar bone.