Al2O3-ceramic as material for dental implants: experimental and clinical study for the development of screw- and extension-implants.

A screw implant and a blade-vent implant were developed for the alloplastic substitution of teeth. Forty implants were observed for 18 months in five beagles; these implants were under maximal functional mastication. No implant was lost. The screw implant showed a tight attachment of bone over the whole implant surface. With the blade-vent implant we observed a partial interposition of connective tissue. This difference seems to depend on the different insertion techniques. Photoelastic studies showed a good stress distribution through enlarged and rounded off attachment surfaces. The described insertion techniques allowed a primary tight attachment of the implant surface and bone support, which led to an immediate stability of position. In the screw implant the physiologic mobility of teeth was imitated by means of a resilient element. Data from 30 cases were gained in a clinical 3-year follow-up. One case failed. For conclusive judgement, a longer period of time and more clinical cases are necessary, but existing data are encouraging.