MATERIALS FOR ENDOSSEOUS DENTAL IMPLANTS

The goal of placement of endosseous dental implants is to achieve osse ointegration or biointegration of the bone with the implant. A wide va riety of materials has been used for these implants, but only a few pr omote osseointegration and biointegration. Titanium and titanium alloy (Ti6Al4V) have been the most widely used of these materials. The surf ace oxide of titanium appears to be central to the ability of this mat erial to osseointegrate. The oxide limits dissolution of elements and promotes the deposition of biological molecules which allow bone to ex ist as close as 30 Angstrom to the surface of the implant. The details of the ultrastructure of the gap between the implant and bone remain undefined, and the consequences of elements which are released on the interface over time are not known. These areas of investigation are pa rticularly important in defining the differences between commercially pure titanium implants and those made of titanium, aluminium and vanad ium. The epithelial interface between the gingiva and titanium appears to contain many of the structural characteristics of the native tooth -gingiva interface, but details are still vague. The connective tissue interface with the titanium appears to be one of tightly fitting tiss ues rather than adhesion. Ceramic coatings appear to improve the ingro wth of bone and promote chemical integration of the implant with the b one. The characteristics of these coatings are complex and affect the bony response, but the mechanisms remain obscure. The degradation of t he coatings is an issue of particular controversy. Progress in dental implantology is likely to continue as the interface between the materi al and bone is more clearly understood, and biological molecules and a rtificial tissues are developed.