Patterns of cortical bone growth around alumina implants

Intra-bony defects are frequently observed around endosseous implants. It has been thought that these are due to occlusal loading and infection. More recently it has been suggested that they may be related to implant shape. This hypothesis has been tested using alumina implants with flat, cone shaped and flared ends, which were inserted into the mandibles and iliac crests of rabbits. The implants remained in situ for up to 18 months and the tissue reaction was studied qualitatively and quantitatively using resin embedded histological sections. New bone was laid down parallel with the implant surface and at a pronounced angle to that in the cortex. Deep intra-bony defects were seen adjacent to the flared implants and, to a lesser extent, the straight ones. Tapering implants appeared to encourage bone growth on the implant above the level of the cortex.