Preliminary Findings on the Role of Sclerostin in the Osseointegration Process Around Titanium Implants

Purpose: Studies have recognized the importance of Wnt/β-catenin signals in osteoblastogenesis. Sclerostin is a glycoprotein product of the SOST gene that inhibits Wnt/β-catenin signaling and reduces osteoblastogenesis. To date, there is little evidence regarding the role of the Wnt/β-catenin pathway and its inhibitors in the osseointegration process. Therefore, the aim of this study was to evaluate the expression of sclerostin in bone healing around titanium implants inserted in rats. Materials and Methods: Fifteen Wistar rats received an implant with primary stability in a tibia, while the contralateral tibia received an implant without primary stability, representing experimental models of implant success and failure, respectively. Animals were then euthanized 7, 14, or 21 days later (five each day). Immunohistochemistry was used to evaluate the specimens for sclerostin-positive cells. Results: The proportion of cells positive for sclerostin was significantly higher around implants without primary stability than those with primary stability at 7 and 14 days after implant placement (P .05). There were no differences between groups for the proportion of cells positive for sclerostin at 21 days after implant insertion (P > .05). Conclusion: Sclerostin expression is upregulated around implants inserted without primary stability, in comparison with that around implants inserted with primary stability, in the tibia of rats. This preliminary evidence reinforces the importance of primary implant stability from the biologic viewpoint. Keywords: dental implants, osseointegration, sclerostin protein, SOST protein