Experimental Study Of Onlay Bone Grafting With Topical Application Of Zoledronic Acid

Objective:The aim of this study is to explore the effect of inhibiting bone resorption and maintaining bone augmentation by local application of zoledronic acid with onlay bone graft animal model by autogenous tibial bone graft.The local surfece of the graft bone is covered by zoledronic acid-collagen membrane and no-load collagen membrane as comparative study respectively,It elects the method of the same body control to provide a clinical method to inhibit postoperative resorption when using onlay bone graft increasing bone mass for where is insufficient bone for inplanting.Method:(1)Animal model:Fifteen white healthy male New Zealand rabbits with an average weight of about2.5-3.0kg.They are randomly divided into three groups of five rabbits in each group in accordance with different observation time.The mandibles of each rabbit were divided into experimental groups and control groups at random.Experimental groups:autologous tibial titanium screw+zoladronic acid collagen membrane;Control groups:autologous tibial+titanium screw+empty collagen membrane.The skin, subcutaneous tissue and muscle were incised along the border of the submandibular region to expose the buccal cortical bone of mandibular body and make surface roughness after general anesthesia.Autologous tibial with the same size of15mm×10mm×2mm cube were implanted as onlay grafts in each side of mandibles at random,which covered by zoledronic acid-collagen membrane and no-load collagen membrane in accordance with the principles of the randomized controlled,fixed by titanium screw and sutured.(2)The observation method:The rabbits were respectively sacrificed five by air embolisms at4weeks,8weeks,12weeks after bone grafting.The vitro specimens were generally observed bone heights and volume changes after bone grafting,Which also were collected for X-ray and speculated the situation of new bone formation by image processing software,bone height and bone resorption by drainage method.Then specimens were fixed, decalcified, HE staining and Masson trichrome for histological observation.The graft-host bone interface healing situation were evaluated by using the computer-assisted image analysis system.Results:(1):General situation:All wounds healed well without infection, necrosis, abnormal bleeding.The vitro specimens:The grafting bone height of the experimental group and the control group are gradually reduced with the extension of the observation time.The two groups all showed that the marginal bone height significantly lower than the central’s,but the bone height of the control group was significantly lower than the experimental group at the same time.(2)Radiological observation:The graft-host bone interface density of the experimental group and the control group are all uneven at four weeks with X radiopaque images showed.The graft-host bone interface of the experimental group was bone connection,the density of which close to the host bone,the height was not changed significantly and the edge of it irregulars at eight weeks.The graft-host bone interface of the control group bone is not clear with X radiopaque images showed,which the graft bone density is lower than the host bone and the bone height reduced as the edge was absorptioned.The graft-host bone interface of the experimental group was completely bone connected and its marginal bone height reduced at twelve weeks.The control group graft-host bone fusion without boundaries and whose graft bone’s shape irregular and height significantly low.Analysising the bone height showed:The mean bone height reduction percentage of the control group is greater than the experimental group at the same period and all showed that the marginal bone height decreased significantly.The average bone height reduction percentage of the two groups were no statistically significant at each observation point at four weeks and eight weeks,but the differences were statistically significant at twelve weeks.(3)Histological observation:The new bone tissues were formated at the experimental and control groups,however,but the trabecular numbers and volumes of new bones of the experimental group better than the control group at the same observation points.The experimental group newborn trabecular bone is more mature than the control group’s with the Masson trichrome.(4)Analysising the bone volume:The average bone volume resorption rate of the control group is greater than the experimental group at the same time,but the difference with no statistically significant at four weeks and eight weeks after operation.The average bone resorption rate of the experimental group is14.65±3.19%,the control group is25.87±4.41%,P<0.05, they have the statistically significant.Conclusions:The graft bone with the host bone in the term of osseointegration by topical application of zoledronic acid in experimental onlay bone graft study.It agreed that the application of zoledronic acid can inhibiting bone resorption, as it was topical used in the experimental onlay bone graft, compared with the control group, which can promote early bone formation, inhibit the bone volume resorption and maintain bone incremental well.Topical application of zoledronic acid in the onlay bone graft at the case of lacking bone mass inhibits bone resorption and maintains bone increment is a clinical viable repair method.