Peri-implant Bone Response Around a Human Hydroxyapatite-Coated Implant Retrieved After a 10-Year Loading Period: A Case Report

This case report presents a histologic and histomorphometric evaluation of the peri-implant tissues of a HA-coated implant retrieved due to peri-implantitis after a 10-year loading period. The implant was retrieved with a trephine and treated to obtain thin ground sections. At low-power magnification mostly compact, mature bone with small marrow spaces could be observed at the interface with the implant. The coating was always present in the areas where bone was detected, the bone was always in close contact with the coating, and there was no detachment between the metal and coating or between the coating and bone. Areas of bone remodeling were demonstrated by the presence of many secondary osteons and reversal lines close to the implant surface. The bone-implant contact percentage was 36.3% ± 1.2%. The percentage of the implant surface covered by the HA coating without bone, where bone may have detached during retrieval, was 32.6% ± 2.8%. This HA-coated implant, continued to demonstrate more than adequate BIC after many years of function and the potential to maintain osseointegration in the long term. Keywords: coating failure, coating resorption, histology, hydroxyapatite coating, long-term study