[The effect of the shape of aluminum oxide-ceramic implants on its staying power in the dog mandible].

Investigations were carried out on implants of Al2O3 ceramic as secondary single toothe replacement in the lower jaw of young Beagle test dogs. Two basically different forms with altogether 7 variations were tested: the first three types of implants had conical roots and a further 4 had cylindrical roots. Common to all 7 types was an implantation shoulder which was tested for its ability to conduct the masticatory force via the cortical substance to the mandibular bone. All implants are at least under indirect masticatory strain; type 80-40-027-00 was directly under strain: part of the implant, shaped like a premolar protrudes through the gum directly into the oral cavity. Preliminary results show that cylindrical root shapes stood the test well. Their length was of no great importance. Conical root shapes without special provision of retention are not suitable. Firm positioning of the implant during introduction is of prime importance. A cortically placed implantation shoulder is not suitable for the conduction of the masticatory pressure into the mandibular bone in dogs.