Objective To explore the effect of tissue-engineered bone Bio-Oss bone combined with platelet-rich fibrin (PRF) on repairing periodontal bone defects by examining the expression of bone morphogenetic protein 2 (BMP-2) , osteoprotegerin (OPG) and nuclear factor κB receptor activator ligand (RANKL) .
Methods A total of 36 three-month-old male New Zealand white rabbits were divided into four groups by random number table method, i.e., Bio-Oss group, PRF group, Bio-Oss/PRF group and blank control group. For each group, there were nine rabbits. Unilateral periodontal was prepared. In the bone defect model, Bio-Oss bone, PRF and Bio-Oss/PRF composite were implanted in the bone defect, respectively, and the one without any material was used as a blank control. The animals were sacrificed at 4, 8 and 12 weeks after the operation. Gross observation, Masson staining and immunohistochemical observation of BMP-2, OPG, RANKL were performed, and the expression of the animals was analyzed by factorial design.
Results Masson staining results showed that in the Bio-Oss/PRF group, some mature bones were observed at 8 weeks after surgery, and bone plates were formed at 12 weeks, with a high bone maturity. Factorial analysis showed that the expression of BMP-2 in the Bio-Oss group gradually increased at 4, 8 and 12 weeks, and the difference was statistically significant (F = 51.30, P<0.001) ; the expression of OPG first rose then descended, and the difference was statistically significant (F = 167.03, P<0.001) ; the expression of RANKL gradually decreased with time, and the difference was statistically significant (F = 5.39, P = 0.046) . The expression of BMP-2 in the PRF group at 4, 8 and 12 weeks was not statistically significant (F = 0.68, P = 0.544) ; the expression of OPG and RANKL decreased gradually over time, and the difference was statistically significant (FOPG = 1070.93, POPG<0.001; FRANKL = 2306.15, PRANKL<0.001) . The expression of BMP-2, OPG and RANKL in the Bio-Oss/PRF group gradually decreased at 4, 8 and 12 weeks, and the difference was statistically significant (FBMP-2 = 13.29, PBMP-2<0.001; FOPG = 237.91, POPG<0.01; FRANKL = 132.48, PRANKL<0.001) . In the blank control group, the expression of BMP-2 and OPG increased first and then decreased at 4, 8 and 12 weeks, and the difference was statistically significant (FBMP-2 = 88.33, PBMP-2<0.001; FOPG = 30.06, POPG<0.001) , while the expression of RANKL gradually decreased over time, and the difference was statistically significant (F = 56.52, P<0.001) .