Abstract
Zirconia ceramic screw pins, 3 mm in diameter and 16 mm in length, were implanted in the lower first and second molar areas of two monkeys (Macaca fascicularis) two months after tooth extraction. Two months after the implantation, each monkey received a continuous crown with metal crowns set on implant pins the right second premolar and third molar, designated the functional implant side. Zirconia ceramic pins on the non-functional implant side were not covered with metal crowns. The tissue-zirconia ceramic pin interfaces of the functional implant side were histologically compared with those of the non-functional side. Zirconia ceramic pen-implant tissue (periimplantium) was distinguished from the normal tooth periodontium by newly formed tissue elements. At the implant contact epithelium interface, ultrastructural elements were similar to the junctional apparatus of enamel-junctional epithelium interface. This provided direct adhesion between the implant contact epithelium and the implant body. In the subepithelial fibrous tissue, mature and dense collagen fibers with a few inflammatory cells were arranged in parallel or irregular patterns on the implant surface area. Ultrastructurally, the fine granular matrix, collagen fibrils, and the cellular membrane of the fibroblastic process appeared in the interface zone of the subepithelial fibrous tissue. Fibrous capsulation almost never appeared at the interfaces of any functional or non-functional sides of the implant body. Ultrastructurally, the zirconia ceramic implant bodies directly contacted the implant supporting bone or were separated by an electron dense amorphus material layer. These results suggest that zirconia ceramic is a excellent material for endo-ossous dental implants.
