An investigation of reosseointegration according to time course after mechanical loosening of the osseointegrated implant fixtures

ABSTRACT

PURPOSE: The purpose of this study was to investigate the reosseointegration periods when the rough surface implants, which had complete bone-implant ankylosis, suddenly losed the osseointegration. MATERIALS AND METHODS: The implants with RBM surface treatment were inserted into both tibias of 23 rabbits. Two implants were submerged into each side. After six weeks, the primary removal torque was measured by Digital torque gauge, and then the implants were replaced and submerged to estimate the level of reosseointegration. After assigned healing periods for each group, the removal torque was measured again. BIC (Bone-Implant contact, %) ratio was measured through histomorphometric analysis.Paired t-test was processed by SPSS 14.0. One-way ANOVA and Tukey's post-hoc test was processed to analyze statistically significant differences among the groups. RESULTS: In comparison with the primary removal torque, the secondary removal torque was increased after 11 days and significantly increased from 2 weeks. In fluorochrome labeling, the origin of mineralization was observed after 7 days, which showed as fluorescent bands around the boneimplant interfaces. After 11 days, the bone formation was apparent, and it is increased continuously with the passage of the time. CONCLUSION: In 11 days after the implant replacement, the secondary removal torque was almost as same as the primary value, and was significantly higher from 2 weeks. The mineralized shapes were observed in 7 days after the implant replacement, and then thebone formation appeared visibly in 11 days.