COMPOSITE MORPHOLOGY OF THE BONE AND ASSOCIATED SUPPORT-TISSUE INTERFACES TO OSSEOINTEGRATED DENTAL IMPLANTS - TEM AND HVEM ANALYSES

Correlated transmission electron and high-voltage electron microscopic analyses examined the undecalcified bone and associated support tissu es of 60 endosseous titanium blade and titanium and ceramic root-form implants in dogs. The implants supported fixed partial dentures for up to 2 years. Data obtained from this investigation suggest that a rang e of tissues, both mineralized and unmineralized, support osseointegra ted dental implants. This study examined the tissues apposing not just isolated aspects of the implant surface, but the entire length of the implant, and found that mineralized and unmineralized tissues existed concurrently. Much of the implant surface was apposed by mandibular b one, and both root-form and blade implants osseointegrated. The densel y mineralized collagen fibril matrix was often separated from the impl ant by only a 20-nm to 50-nm electron-dense, ruthenium-positive deposi t. High-voltage electron microscope stereology demonstrated that cellu lar processes extended directly to the implant from underlying osteocy tes. In the same implants, areas containing an unmineralized collagen matrix interposed between the bone and implant surface were observed. In this region osteoblasts interacted with this matrix, and Howship's lacunae, containing vascular elements and osteoclasts, were also obser ved. The remodeling activities appear to be a homeostasis of catabolic activity (osteoclasts) and metabolic activity (osteoblasts). The apex of the implant was often apposed by a fibrofatty stroma. The support tissue response appears to be the result of the interrelations of oste oblasts, osteocytes, and osteoclasts in association with vascular elem ents. Therefore, the support tissue response to osseointegrated implan ts is a dynamic activity that involves the healthy interaction of thes e cells and tissues along the entire length of the implant.