Bone Cell Apoptosis In Experimental Diabetic Periodontitis In Rats

objective:The goal of this study was to investigate the role that matrix-producing cell apoptosis plays in the diabetic periodontitis-associated bone loss.methods:Sixty-two six-week-old male SD rats were randomly divided into three groups :diabetic periodontitis group(DP), periodontitis group(P) and normal control group(N). Diabetic rats were induced by intraperitoneal injection of streptozototocin (STZ). Periodontitis was initiated by ligating floss around maxillary second molars and oral inoculation with periodontal pathogen Porphyromonas gingivalis.Three or six weeks later,the animals were sacrificed and the specimens were prepared for histological analysis.Assessment was carried out using a number of different visual and histological approaches. Visual assessment included probing depth(PD) and alveolar bone loss(ABL).Histological examination included PDL fibroblast numbers, osteocyte numbers,osteoclast numbers in the inflammatory area, osteoclast numbers in the non-inflammatory area, the percentage of apoptotic fibroblasts, the percentage of apoptotic bone-lining cells /osteoblasts, the percentage of apoptotic osteocytes.Statistical significance was determined by one-way ANOVA with significance set at P< 0. 05.results:The sequence of mean probing depth and mean alveolar bone loss among each group is group DP > group P > group N. Intergroup comparisons demonstrated that periodontitis and diabetic periodontitis might reduce the number of PDL fibroblasts and osteocytes.Moreover,the number of PDL fibroblasts and osteocytes in group DP was also decreased compared with group P(P< 0. 05). Intergroup analysis revealed higher osteoclast numbers in the inflammatory area of group DP and group P when campared with group N(P< 0. 05). And campared with group P, group DP had more higher osteoclast numbers(P < 0.05). But the osteoclast numbers in the non-inflammatory area shows that group DP < group P < group N. Periodontitis and diabetic periodontitis also increased apoptosis of fibroblasts, bone-lining cells /osteoblasts and osteocytes. The percentage of these apoptotic cells was approximately 2-fold higher in group DP vs. group P.conclusions: Taken togrther,the present study clearly demonstrates that diabetes can increase the severity of periodontitis. Accelerated alveolar bone loss was observed in diabetic rats.Increased osteoclast numbers in the inflammatory area in diabetes may contribute to the exaggerated destruction of alveolar bone.Diabetes actually inhibited the formation of osteoclasts in the non- inflammatory area .Our findings establish that matrix-producing cell apoptosis is involved in the pathogenesis of periodontitis.Diabetes can increase the apoptosis of fibroblasts, bone-lining cells /osteoblasts , osteocytes and decrease the number of these cells. Thus,diabetes may enhance periodontitis-associated bone loss by increasing the formation of osteoclasts and enhancing apoptosis of matrix-producing cells in the periodontal tissue.