Biomechanical analysis of the osseointegration of porous tantalum implants

Statement of problem. Although implants containing porous tantalum undergo osseointegration, whether this material significantly alters new bone formation and improves implant stability during healing in comparison to titanium is unclear. Purpose. The purpose of this in vivo study was to determine the influence of the inclusion of porous tantalum into a dental implant on the biomechanical properties of the bone-implant interface and peri-implant bone which may contribute to secondary implant stability. Material and methods. Threaded titanium implants with a porous tantalum midsection (Trabecular Metal Dental Implant; Zimmer Biomet) or without (Tapered Screw-Vent; Zimmer Biomet) were placed in rabbit tibiae and allowed to heal for 4, 8, or 12 weeks. The implants were evaluated by resonance frequency analysis and removed with surrounding bone for nanoindentation testing. Two-way ANOVA was used to determine the impact of implant type, bone region, and time on the outcomes implant stability quotient (ISQ), hardness, and elastic modulus (alpha=.05). Results. Resonance frequency analysis found no significant difference in ISQ values between implant types at 4, 8, or 12 weeks, and ISQ values did not increase for either implant over time. Nanoindentation showed no significant differences in hardness or elastic modulus in newly formed bone adjacent to either implant type at any time point. Conclusions. The stiffness of the bone-implant interface was similar for threaded titanium implants with or without porous tantalum when placed in the rabbit tibia and allowed to heal for at least 4 weeks. The new peri-implant bone adjacent to dental implants containing porous tantalum showed no difference in nanomechanical properties to the new bone around implants comprised completely of threaded titanium at all healing time points.