Human Histologic and Histomorphometric Analyses of Hydroxyapatite-Coated Implants After 10 Years of Function: A Case Report

Purpose: No consensus exists on the long-term performance of hydroxyapatite (HA) coatings on dental implants. The aim of this study was to evaluate the long-term stability of the HA coating in a human autopsy specimen. Materials and Methods: Two mandibular HA-coated implants were retrieved postmortem from a woman after 10 years of functional loading with an implant/tooth-supported fixed partial denture. After ground sectioning, the specimens were histomorphometrically analyzed. Results: Direct bone-implant contact was found at 78.48% of the implant surface. HA coating disappearance had occurred in a few areas (22.75%), but bone was in direct apposition to the titanium surface. Bone volume measured 27.66%, and expected bone-implant contact was 37.55%. No inflammatory reaction was seen in the supracrestal soft tissues or the bone compartment. Discussion: Most of the HA coating was maintained on the implants, and areas lacking HA were directly apposed by bone. This observation suggests that the underlying titanium surface should have a macro-texture to promote the adaptation of bone to the titanium surface in case of HA disappearance, as well as to decrease failure at the HA-titanium interface. Conclusions: In a patient in whom prosthetic treatment was appropriately performed and proper plaque control was maintained, the HA coating was not damaged and contributed to the success of the implant over 10 years of clinical functioning.