Local Injection Of Puerarin To Absorb The Impact Of The Residual Alveolar Ridge In The Mouse After Tooth Extraction Experiments

OBJECTIVE: Alveolar bone is the foundation of removable partial denture, which is the requirement of the denture's retention and stabilization. After the tooth, bone and soft tissue healing of alveolar ridge is called residual ridge(RR).The balance of bone formation and bone destruction has been destroyed, the irreversible pathological absorption has been appeared on RR, that leads to the oral bone loss and influence the result of denture repairing. Studies has proved that the speed of absorption is the fastest in the first three months of tooth, and the absorption is continuous with the low speed in the later life, the phenomenon is called residual ridge resorption (RRR).The quality of denture's repair function has been influenced by RRR.The patient who accepts dental implant therapy may face the higher failure rate because of RRR. Therefore, the way of inhibited RRR has been studied for a long time.Puerarin root has a high nutritional value. It is a kind of perennial leguminosae herbaceous plant, which can be used in not only medicine area but in foodstuff area. It has the effect of clearing away heat and toxic material and activating blood and dissolving stasis. At present, it has been used in many areas such as cardiovascular disease,incretopathy,ophthalmology and so on. The chemical name of puerarin is 8-β-D-glueopyranosyl-7-ydroxy-3-(4-hydroxyphenyl),the molecular formula is C21H20O9. Studies show that many isoflavones which have estrogen-like activity can improve the quality of bone rebuilding. This research is based on the model of RRR in rats, puerarin was injected into the submucous of residual ridge. Study the effect that Puerarin can inhibit the RRR in animal experiment which was based on the vitro experiments .METHODS: The 60 healthy 16weeks male Wistar rats were allocated at radom into two groups,experiment group and control groupe. Right mandible central incisors were extracted, to establish the rat's experimental model of the residual ridge resorption(RRR). Puerarin was injected into the submucous of residual ridge in experiment group,control group inject saline in the same way once every three days.All rats in experiment group and control group were perfused and sacrificed at 7 day,14 day,21 day,28 day,35 day. Dissect all rats'mandible, relative heights of residual ridge and bone mineral densities were measured by X-ray photographs, morphologic alteration of residual ridge was observed by hematoxylin and eosin at different times, and all the results were analyzed by the computer image analyzing system and treated by statistics test. RESULTS: The result show that the relative height of residual ridge resorption of test groups were higher significantly than control groups (p<0.05), the bone mineral density of test groups were larger significantly than control groups ,except one week group(P<0.01). Histological morphology: 7 days group, socket appears alveolarresorption both in experiment group and in control group, inflammatory infiltration, bone lacunas were appeared on surface of bone, there are many multinucleated osteoclasts in bone lacunas. 14 days proup, multinucleated osteoclasts were less than 7 days group,compared with the control group, the number of osteoblasts were higher.,the amount and velocity of the new bone formation are more than the control group. 21 days,the level of the alveolar absorption were lower, there were a large number of mature bone matrix which took place the new bone formation in the experiment group. Compared with the experiment group,the amount and the extent of the new bone formation were less.28 days, there were many new bones in socket of the experiment group, bone islands were appeared.35 days, hyphology observed conclusion show that woven bones were appeared in the experiment group. We can see the mineralization evidently on the surface of neoplastic bone formation, bone trabecula are dense.CONCLUSION: Base on establishing the rat's experimental model of the residual ridge resorption(RRR), we observed the effects of puerarin on residual ridge resorption after extration in rats, the result show that residual ridge resorption can be inhibited by puerarin which was injected into the submucous of residual ridge, and the height of the alveolar bone can be conserved. Trough the study we can conclude that puerarin can inhibit alveolar bone resorption after tooth extraction, and provid powerful experiment evidence on clinical application.