Experimental Study On Onset Enhancement Of Periodontitis Induced By Cyclophosphamide

Objective: To establish experimental periodontitis model in Wistar rats bycyclophosphamide peritoneal injection and ligaturing their lower left first molars with silk inorder to observe the depth of periodontal pockets and the alveolar bone destruction, toinvestigate the effect of cyclophosphamide on the onset of periodontitis. Trying to elucidatethe mechanism of alveolar bone destruction in periodontitis, then provide original theoryinsight.Methods: 66 five-month-old Wistar rats were randomly divided into 5 groups: normalcontrol group(n=6), ligation plus cyclophosphamide group(n=15), ligation group(n=15),cyclophosphamide group(n=15) and model control group(n=15). The rats of the ligation pluscyclophosphamide group and the ligation group were ligatured with silk on the lower leftfirst molars to induce periodontitis. Meanwhile the rats of ligation plus cyclophosphamidegroup and cyclophosphamide group were given peritoneal injection with cyclophosphamide.The rats of every group were sacrificed 2 weeks, 4 weeks and 7 weeks after experimentrespectively. Body weight, pocket probing depth and sulcus blooding depth were measuredand blood samples were collected in order to obtain leucocyte count. Mandibule specimenradiographs and photographs were taken with X-ray machine and digital camera respectivelyto observe the alveolar bone destruction and evaluate the extent of the periodontal bone loss.The samples were prepared for hematoxylin and eosin(HE) stain and observed histologically.Then the osteoclast count were obtained. The right alveolar bone of the molars were taken,digested with hydrochloride acid. Atom spectro-absorptiometer was used to determine thecalcium content of bone.Results: Body weight of the rats in ligation plus cyclophosphamide group andcyclophosphamide group cut down gradually. Their body weight was significantly lowerthan those in model control group at the fourth and seventh weeks. Statistically significantdifference in PPD and SBI exist between ligation plus cyclophosphamide and model controlgroups after 4,7 weeks of experiment. In ligation p/us cyclophosphamide group andcyclophosphamide group, at week 4 and 7, the leukocyte count was higher significantly thanthose in model control group .At week 4 and 7, resorption of alveolar crest was observed inligation plus cyclophosphamide and ligation groups, and the former was more serious than the latter; statistically significant difference in the destruction extent of buccal alveolar boneand the exposure length of lingual root cones was observed between ligation pluscyclophosphamide group and ligation group.Compared with model control group, theosteoclast count of ligation plus cyclophosphamide, ligation and cyclophosphamide groupswas higher respectively at week 2, 4 and 7.At week 4 and 7, calcium content of the rightalveolar bone of the molars was lower in ligation plus cyclophosphamide group andcyclophosphamide group than in model control group.Conclusions: Periodontitis models in rats are established successfully by cyclophosphamideperitoneal injection and silk ligation. Cyclophosphamide speeds up the development ofperiodontitis by reducing leukocyte count and resulting in lower secretion of sex hormoneand bone metobolism disturbance. The effect of cyclophosphamide is posotive related toaction time.