Prospective controlled clinical study investigating long-term clinical parameters, patient satisfaction, and microbial contamination of zirconia implants

Background Dental implants made of zirconia ceramics experienced a renaissance in the past years. However, there is still a lack in reliable long-term clinical data. Purpose Aim of the present prospective clinical study was to analyze the dental implants made from zirconia, regarding their clinical performance compared to natural teeth (control). Materials and Methods Eighty-three zirconia implants in 28 adults were analyzed after 7.8 years of integration. Approximal plaque index (API), sulcus bleeding index (SBI), probing pocket depth (PPD), probing attachment level (PAL), and creeping or recession (CR/REC) of the mucosa/gingiva were analyzed. Changes in the marginal bone level (MBL) have been determined by comparing radiographs recorded immediately after implant placement and at the follow-up investigation. Furthermore, the pink esthetic score (PES), Periotest values (PTV), microbial colonization of the implant/dental sulcus fluid, and patient satisfaction were assessed. Results The survival rate of zirconia implants was 100%, however one implant presented a profound peri-implantitis, resistant to therapies. No statistical significance was observed between implants and teeth regarding SBI and PAL. Statistical significance was detected regarding API and CR/REC with significantly less plaque accumulation and recession in the study group. Significantly higher values for PPD were obvious in the zirconia implant group. PES of 9 +/- 2.7 indicate a rather average esthetic result. Analysis of MBL revealed a mean peri-implant bone resorption of 1.2 mm. Microbial analysis revealed a nonstatistically significant higher colonization of bacteria in the study group, whereas single bacteria species were detected in statistically significant higher amounts. Conclusion The investigated one-piece zirconia dental implants presented favorable long-term clinical results, comparable to natural teeth (SBI and PAL), and, regarding adhesion of plaque and creeping attachment (CR/REC), even superior. The microbial investigation revealed a shift in peri-implant colonization around zirconia implants over years, mainly without clinical effect on peri-implantitis.