| Objective: Tooth immediate implant model were set up firstly by extracting the central incisor both in maxillary and mandibular of rabbits. Then the nano-hydroxyapatite and nano-hydroxyapatite with zoledronate were used respectively to filled the sockets made by incisors removal immediately. The aim of this study was to investigate the role of local application of zoledronic acid on implant osseointegration by observing the osseointegration around the bone of titanium screw.Methods:1 Group:Nine New Zealand white rabbits were divided into two groups randomly: 6 in experimental group and 3 in control group. In experimental group, the sockets would be filled with the nano-hydroxyapatite and zoledronate compound; and in control group, be filled only by nano-hydroxyapatite. Then one titanium screw as implant was insert into each socket.Specimens were harvested separately by killing animals at 4th 8th and 12 th week after operation, which two in experimental group, and one in control group for each time.2 Preparation of the mixture of nano-hydroxyapatite and zoledronate : 10 g nano-hydroxyapatite was put into 5 ml zoledronate solution(0.2mg/ml) for 24 h, and then was dried and sealed to be used.3 Preparation of animal model: Incisors would be extracted just before the procedure completed as follows: drilled off the half crown of each incisors under local anesthesia, and kept doing this for another three times once a week.4 Implant:After tooth extraction, we filled nano-hydroxyapatite with zoledronate into each socket in experimental group, and then screwed one titanium screw in it. In control group, Nano-hydroxyapatite was filled into each socket, and then the titanium screw. The incision was sew up at last for every animal.5Observations: All animals were killed at 4th,8th,12 th week after operation respectively by air embolism. The healing situation of each sample was observed by gross observation. The osseointegration around implant were test tand analyzed through torque test and hematoxylin-eosin(HE) staining.Results:1 General condition: After operation, no animals were dead. The tissue around the titanium screws did not show any infections, necrosis, etc.2 Gross observation:All the titanium screw were stable at every period both in the experimental and he control group.3 The result of torque test:The average of torque peak values in both experimental group and control group increased as time went on, both reached the maximum value at 12 th week.The results had significant difference between the experimental group and the control group at 4th week(P=0.023,<0.05),,8th week(P=0.033,<0.05),and 12 th week(P=0.027,<0.05).4 Histological observations:In the sections from the 4th weeks samples, we saw osteoblast and pink bone matrix in the area of alveolar bone around titanium screw in experimental group, but fewer in contral group. It was observed that a great number of mature osteocyte and a small amount of new-born bone in the experimental group in the 8th weeks sections, but less in control group. In the sections of 12 th weeks, mature osteocyte showed tightly packed and regular arrangement in experimental group, meanwhile in the control group, there was more mature osteocyte could be seen than that in 8th weeks section, but they showed irregular arrangement.5 Osteoblast index: The results had significant difference between the experimental group and the control group at 4th week(P=0.028,<0.05).Conclusion:It was observed that local application of zoledronate could improve osseointegration between implant and alveolar bone, prevent bone absorption, thus could enhance the stability of implant. |
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