The advantages of transmucosal healing implants with a bioactive zirconia collar as a support for partially fixed prosthodontic restorations are optimal peri-implant marginal tissue sealing, reduction in plaque accumulation and satisfactory aesthetic results. The zirconia used in this study evidenced not only optimal clinical performances, but also good biocompatibility. The results from this study demonstrated that zirconia coating enhances fibroblasts and osteoblast-like cell adhesion, spreading and proliferation, favoring microscopic tissue/cell in-growth and clinical implant fixation improvement. From clinical analysis, it emerged that the treatment group obtained better scores in every peri-implant parameter. This evidence attests faster stabilization of soft and hard tissues around both the transmucosal zirconia collar and at the crestal level of the implant. A reduced plaque accumulation around the implant with zirconia collar could provide a better peri-implant microbiological en-vironment by allowing the soft tissues expression of optimal sealing and good bone adaptation to loading. From these clinical and radiographic comparative analyzes, it emerged that in the treatment group the mean values were always similarly low. A rapid stabilization of both hard and soft peri-implant tissues was documented in the 1st yr. In the treatment group, there was the formation of stable tissue sealing the zirconia collar, which could preserve mucosal and bone levels. In conclusion, 2-yr clin-ical results demonstrated that implants supporting fixed restorations using transmucosal healing implants with a zirconia collar appeared a valid method, reporting 100% implant survival rates. Moreover, in vivo results obtained using strict parame-ters to assess the peri-implant status affirmed that a zirconia collar offers excellent biological acceptance. Our preliminary in vitro results statistically evidenced increased fibroblast and osteoblast adhesion and proliferation to zirconia compared to tita-nium, and an index of enhanced material integration with bone and soft tissue cells. (Journal of Applied Biomaterials & Biomechanics 2004; 2: 143-50).