Therapy With Calcitonin And1,25Vitamin D Prevents Periodontitis-induced Alveolar Bone Loss In Rats

Objective:The purpose of this study was to establish a preiodontitis model and evaluate the effects of calcitonin and1,25vitamin D on bone loss in experimental periodontitis rats. Observed clinical assessment included probing depth (PD) and alveolar bone level.Serum bone-specific alkaline phosphatase (BALP) and osteocalcin (OC) were measured by enzyme-linked immunosorbent assay (ELISA).Methods:125male Wistar rats were randomly divided into five groups according to the treatments during8weeks:normal control (group A)、periodontitis group (group B), calcitonin (group C, prepared in sterile saline at2μ.g/ml, and2μg/kg was administered daily, s.c.),1,25vitamin D (group D, prepared in corn oil daily at a concentration of2μ.g/ml, and2μg/kg was administered daily, p.o.),1,25vitamin D plus calcitonin (group E).In order to induce experimental periodontitis, the B、C、D、 E groups were established by ligating floss around mandibular first molars with orthodontic wire ligature wire and a4/0silk suture was placed and knotted submarginally,by the same operator,aroud the gingival margin of the mandibular first molars of the rats.The sutures were checked after application,and lost or loose sutures were replaced.Body weight change,activity coat color were observed.During the8-week treatment period, animals were sacrificed and the specimens were prepared. Serum bone-specific alkaline phosphatase (BALP) and osteocalcin (OC) were measured by enzyme-linked immunosorbent assay (ELISA). Observed clinical assessment included probing depth (PD) and alveolar bone level.The mandibules were used for pathological analysis.Histological examination included both periodontal membrane fiber and alveolar bone inflammatory. Data from each expeimental group were expressed as mean±standard error of the mean,and the differences among groups were analyszed by one-way analysis of variance,LSD-t test..P values lower than0.05were considered statistically significant.Results:Lively, well-proportioned body,responsive,smooth coat,body weight increased steadily with increasing weeks of age were observed in group A.Food impaction,saliva more,less drinking water,less urine output were observed three days after established by ligating floss around mandibular first molars with orthodontic wire ligature wire in group B、C、D、E.Body weight increased steadily with increasing weeks of age. The probing depth and alveolar bone loss among each group was showed difference in each time sites.2weeks later,intergroup comparisons demonstrated that periodontal pocket probing depth in groupBwas highter than group A. Group E might reduce the probing depth compared with group B、C、D at4,6and8weeks(P<0.05).2weeks later,intergroup comparisons demonstrated that periodontal bone loss in groupBwas highter than group A. The alveolar bone loss in group E was decreased compared with group B、C、D at6weeks and8weeks(P<0.05).Calcitonin,1,25vitamin D partially inhibited alveolar bone loss compared with group E(P<0.05).8weeks later, Surum BALP in group A was higher than group B. Serum BALP increased significantly in group E compared with group B, C and D(P<0.05).Surum OC in group A was higher than group B. Serum OC increased significantly in group E compared with group B, C and D(P<0.05).In the8th week histological examination demonstrated that group A and group E had less inflammation cell in the gingival epithelium and lamina propria,the periodontal membrane fiber was well-arranged,and the newly foemed bone was observed.The inflammation was serious in groupB.Conclusions:1.Vitamin D deficiency,lack or imbalance of calcium or phosphate could lead to reducrd osteogenic ability in alveolar bone.2.1,25vitamin D, calcitonin and both partially inhibit the alveolar bone loss inducing by periodontitis. Especially, the application of both is more effective than either drug treatment alone.