Histopathologic observations on early oral implant failures.

The purpose of this study was to morphologically describe the tissues surrounding 20 early failed (prior to prosthesis placement) Brånemark System oral implants. The implants and their surrounding tissues were consecutively retrieved and analyzed with light microscopy and transmission electron microscopy. Failures were chronologically divided into those occurring prior to, at, and after abutment connection. The clinical conditions varied from osteomyelitis to totally asymptomatic but mobile implants. Different histopathologic pictures were observed, ranging from a stratified, almost acellular, connective tissue layer, via a capsule with a great number of inflammatory cells, to a heterogeneous interface with areas of highly vascularized connective tissue and portions of poorly mineralized bone detached from the implant surface. The histopathologic variation may reflect different etiologies and/or time stages of the failure process. Epithelial downgrowth was occasionally observed for asymptomatic submerged implants. Epithelial cells were attached to the failed implant surface via hemidesmosomes. The histologic, clinical, and radiographic findings together indicated that 3 major etiologies might have been implicated in the failure processes: impaired healing ability of the host bone site, disruption of a weak bone-to-implant interface after abutment connection, and infection in situations with complicated surgery.