Effects Of RGD On The Osseointegration Of Microscrew

ObjectiveTo observe the histological changes of the bone around RGD coated micro-screw under different healing time and research the effects of RGD on the osseointegration. The expression of type I collagen protein (Col I) and osteocalcin (OC) of different healing time were detected and analysed by immunohistochemistry and image analysis system. This study explored the effects of Col I and OC on osseointegration, and to applly the histology and the molecular biology basis for the application of RGD coated micro-screw.MethodsThree18-month male Beagles(around15kg) were used in this study. In the Oth,4th,6th week, the micro-screw of RGD coated and no-coated was randomly inserted in each Beagle’s left or right maxillary respectively. Eighteen micro-screws (RGD group:9,Control group:9) were inserted into the buccal region of the maxillary in3Beagles. Each dog was scheduled to receive six micro-screws in the area of maxillary premolar. After2,4,8weeks of healing, the dogs were sacrificed and all bone-screw specimens were prepared. Histological changes of the bone around RGD coated micro-screw under different healing time were observed. The expression of Col I and OC were detected by immunohistochemistry and analyzed using image analysis system.Results1. Histological observations revealed the level of osseointegration around the micro-screw were significantly higher in the RGD group than in the control group at the2th,4th week, while there was no significant difference after8weeks healing period.2. Immunohistochemistry analysis showed that the expression of Col I and OC were both found in the RGD group and the control group. The expression of them in RGD group were both significantly higher than the control group at the2th and4th week (P<0.05), while there was no difference at the8th week.3. The expression of Col I and OC showed a different tendencies in the immunohistochemistry analysis results. In both groups, the expression of Col I was high at the2th week, increased up to the highest point at the4th week, and then dropped slowly at the8th week, while the expression of OC was significantly increased in the first4weeks, and then kept a high level with the healing process. Conclusions1. The histological observations indicated that RGD promoted the osseointegration during the early phase of healing, and enhanced the initial stability of micro-screw.2. The immunohistochemical analysis results demonstrated that RGD improved the expression of Col I and OC, and increased the biological activity of micro-screw surface. The Col I and OC could play different roles in osseointegration process.