Single crystal sapphire dental implants : experimental and clinical studies

The aim of this project was to evaluate single synthetic sapphire crystals as dental implants, with special reference to correlation of clinical and in vitro/in vivo methods of research. The laboratory studies confirmed chemical stability. The nontoxic properties were confirmed by in vitro tests showing no disruption to normal cell function in cell cultures of human oral epithelial cells and fibroblasts. Tissue-implant interactions were studied in animal experiments: thirty Sprague-Dawley rats were used for subcutaneous implantation and two inbred beagle dogs for mandibular bone implantation. The subcutaneously implanted sapphire rods showed a minimal foreign body reaction after 4-12 weeks in situ. In the intraosseous implantation experiment the implants and surrounding tissues were removed after 6 months in situ: for histological and histometric analysis. Showed that bone contact to the implants was appr. 62% and the peri-implant mucosa closely resembled the mucosa surrounding the tooth.

In the clinical studies, conducted in one Swedish and one Norwegian specialist clinic, 86 patients with edentulous mandibular were treated with overdentures supported by sapphire implants. To determine implant success, clinical evaluation and radiographic features were monitored. Of the initial 324 implants, 28 implants were lost during the first 42 months. For the remaining implants, the cumulative implant success rates, based on radiographic and clinical criteria varied from 95.2% at the end of the prosthetic treatment to 91.3% at the twelve year follow-up. The radiographic analysis of the remaining implants showed no statistically significant changes in the bone implant score index (BIS), measured from baseline to the five year follow-up. Correlation of the experimental and clinical data indicate that the single synthetic sapphire crystal dental implant system is an appropriate method for rehabilitation of mandibular edentulism.