OSTEOGENESIS AT THE DENTAL IMPLANT INTERFACE - HIGH-VOLTAGE ELECTRON-MICROSCOPIC AND CONVENTIONAL TRANSMISSION ELECTRON-MICROSCOPIC OBSERVATIONS

The osteogenesis of mandibular bone to endosteal dental implants was e xamined using an in vivo dog model. One half of the implants examined were unloaded implants, with the remaining one half prosthodontically loaded for 6 months. Undecalcified mandibular implant samples were exa mined with both high-voltage electron microscopy (HVEM) stereology and routine transmission electron microscopy. The osseous interface to in tegrated implants was shown to vary in its morphology. Mineralized bon e was observed directly apposing the implant, often separated from the implant by an electron-dense deposit of approximately 50 nm. Within t his densely mineralized matrix, osteocytes were routinely observed. Ad jacent areas were shown to contain slightly wider zones of either a le ss dense mineralized matrix or, alternatively, unmineralized tissue. O ther zones consisted of wider unmineralized matrices containing collag en fibers and osteoblasts. These latter zones were consistent with the appearance of an appositional type of bone growth. Because bone is a dynamic, actively remodeling tissue, a varied morphology of the suppor t tissues to dental implant is not unexpected. Areas of mature bone in terfacing with successfully integrated implants were demonstrated, as well as areas adjacent to the mature bone that were undergoing remodel ing or mineralization. This study has also shown that HVEM stereology is a valuable research tool to investigate the oral tissue interface w ith dental implants.