Histologic analysis of a fractured implant: a case report.

This study presents the histologic analysis of an implant retrieved 14 months after loading because of a fracture in the collar region. The implant (Biovent) was removed with part of the periimplant tissues, and the block was prepared using cutting and grinding equipment to obtain 3 sections approximately 30 microns thick. The examination evidenced a high degree of osseointegration, with a bone-to-implant contact of 74% +/- 13%. The lamellar bone was dense and in close relation with the hydroxyapatite coating of the implant. The connection between the 0.4-mm hydroxyapatite coating and the metal was always very tight. The thickness of the metal at the break point was assessed to be 1.6 mm. Besides the relative weakness of the metal at the neck of the implant, other possible causes of failure are discussed.