Wear and Corrosion at the Titanium-Zirconia Implant Abutment Interface

Objectives: Dental implants have been shown to have predictable success, but esthetic complications often arise. To reduce tissue shadowing from titanium, zirconia abutments may be used; however, literature suggests that the use of zirconia leads to greater destruction of the implant interface and may result in biological complications such as titanium tattoos and heavy metal toxicity. Previous studies have examined the mechanical aspects of this implant/abutment relationship, but they have not accounted for the corrosive degradation that also takes place in the dynamic atmosphere of the oral cavity. This study investigated the synergistic effect of both wear and corrosion on the materials at the implant and abutment interface. Methods: Utilizing a simulated oral tribocorrosive environment, titanium (Ti) and zirconia (Zr) abutment materials were slid against titanium and RoxolidTM implant alloys. The testing was conducted for 25K cycles, and the coefficient of friction (COF) and voltage evolution were recorded simultaneously. Following the tribocorrosion assays, the wear volume loss was calculated, and surface characterization was performed. Statistical analysis was completed using a one-way ANOVA followed by post-hoc Bonferroni comparisons. Results: Zr/Ti groups had the highest COF (1.1647μ), and Ti/Ti had the lowest (0.5033μ). The Zr/Ti coupling generated significantly more mechanical damage than the Ti/Ti group (p=0.021). From the corrosion aspect, the Ti/Ti groups had the highest voltage drop (0.802 V), indicating greater corrosion susceptibility. In comparison, the Zr/RoxolidTM group had the lowest voltage drop (0.628 V) and significantly less electrochemical degradation (p=0.019). Overall, the Ti/Ti group had the largest wear volume loss (15.1x107 μm3), while the Zr/Ti group had the least volume loss (2.26x107 μm3). Both zirconia couplings had significantly less wear volume than the titanium couplings (p<0.001). Conclusions: This study highlights the synergistic interaction between wear and corrosion, which occurs when masticatory forces combine with the salivary environment of the oral cavity. Overall, the zirconia groups outperformed the titanium groups. In fact, the titanium groups generated 5-6 times more wear to the implant alloys as compared with the zirconia counterparts. The best preforming group was Zr/Ti, and the worst performing group was Ti/Ti.