A 6-year unloaded hydroxyapatite-coated dental implant placed into an extraction socket in conjunction with nonresorbable hydroxyapatite grafting material: histologic evaluation.

A submerged hydroxyapatite (HA)-coated implant placed into a fresh extraction socket in conjunction with a nonresorbable HA graft was harvested after 6 years of unloaded healing. The implant and surrounding bone were processed for histologic analysis. The HA coating appeared to be stable and homogenous. An excellent bone-to-implant contact could be found along the entire implant length. No signs of HA resorption or detachment were found. The HA graft was still recognizable histologically around the apical third of the implant. Light microscopy revealed a good osteoconductive ability of the HA particles, which did not show any signs of remodeling or resorption. These findings suggest that HA-coated implants may be able to maintain optimal osseointegration over time, even in the absence of loading.