Objective: Morphology of implant surface plays important roles in osseointegration of dental implants. Recent studies have reported that hierarchical structured surface showed favorable effects on bone quantity around implant. However, the effects on bone quality remains unclear. The aim of this study was to investigate the effects of implant surface modification with oxalic acid on bone quantity and quality around dental implants in rabbit tibiae.
Materials and Methods: Grit-blasted CP grade Ⅳ titanium implants treated with HCl/H2SO4 and oxalic acid were used as test implants. The implants without oxalic acid treatment was used as a control. Two sets of each implant were placed in the tibial proximal metaphysis of 14 female-Japanese-white rabbits. Euthanasia was performed at 4 and 8 weeks after implant placement (n = 14/group). Villanueva Goldner staining and picrosirius red staining were carried out for histomorphometric analyses to evaluate bone quality and quantity around implant.
Results: No infection was noted in all placement sites. Bone-to-implant contact increased in test group at 4 and 8 weeks post-implantation, whereas bone area fraction and total collagen production were not changed between groups. Bone maturity around test implants was significantly larger than that around control at 8-weeks after implant placement. Increased type I collagen and decreased type III collagen production was significantly observed 8-weeks post-implantation. Moreover, positive effects of morphological changes with oxalic acid treatment on bone area fraction, mature bone, total collagen and type I collagen, and negative effects of it on immature bone and type III collagen was significantly noted in the later 4 weeks post-implantation.
Conclusions: Our findings reveal that the hierarchical structure on implant surface treated with oxalic acid increases bone formation from the early stages and improves bone quality from the late stages, which may contribute to the long-term success of dental implant treatment in clinical situations.