All-ceramic restoration of zirconia two-piece implants--a randomized controlled clinical trial.

OBJECTIVES: Aim of this controlled prospective randomized study was to evaluate the outcome of two-piece zirconia implants compared to titanium implants over a period of up to 24 months. MATERIAL AND METHODS: A total of 31 implants (16 zirconia/Ziterion vario Z((R)) + 15 titanium/Ziterion vario T((R)) ) were inserted primary stable (>30 Ncm) in the maxilla (7) and mandible (24) of 22 patients (13 male, nine female) requiring neither bone nor soft tissue augmentation. After a healing period of 6 months in the maxilla and 4 months in the mandible, ceramic abutments were luted adhesively to the zirconia implants and definitive all-ceramic restoration was performed with high-density ceramics. Radiographic bone levels, condition of the peri-implant mucosa, aesthetic outcome, implant survival and success were recorded for up to 24 months. RESULTS: Measurements of mean marginal bone levels 24 months after surgery showed a significant bone loss (P < 0.001) in both groups (Ti: 1.43 (SD +/- 0.67) vs. Zir 1.48 (SD +/- 1.05). One zirconia implant was lost 8 months after restoration. No further complications were recorded, giving an overall survival and success rate of 93.3% for zirconia and 100% for titanium implants after a period of up to 24 months. CONCLUSIONS: After 24 months, success rates of the two-piece ceramic implants showed no significant difference compared to control two-piece titanium implants. The bonded zirconia implant abutment connection appears to be capable with clinical application over the observed period. However, further control measurements need to confirm the presented data.