The chemical and microstructural signature of peri-implantitis on titanium dental implants’ surface

Titanium and titanium alloys are deemed to be biocompatible materials. But what happens to the biomaterial when the environment and/or the working conditions change? This study aims to identify changes in the surface chemistry and morphology of retrieved titanium dental implants after exposure to the inflammatory conditions that are characteristic of peri-implantitis. The surface of unused (reference) and retrieved dental implants are systematically compared at two distinct scales, namely micron and nano, using high-resolution analysis microscopic methods (SEM, Tof-SIMS and S/TEM). At the micron scale, a profusion of (micron-size) metallic particles were observed only on the top area of the retrieved implants. For those implants, significant nanoscale damage to the (protective) oxide layer was observed, consisting of changes in thickness, composition, and atomic arrangement (amorphization), as opposed to that of the reference implants. An organic compound, denoted by CNx, was found to infiltrate the oxide layer, rendering it significantly thicker, porous, and weak with evidence of delamination. We present a systematic methodology to study biocompatibility and degradation processes in those implants, exposing unambiguously the severe degradation of the protective oxide layer that should guide further studies aimed at increasing the implants’ resistance to their biological environment. The results reported herein do not differentiate between implants of different origins, make and/or patients’ history, so that these results confer a definite generality to the protective layer's degradation related to peri-implantitis.