Methods: 61 patients were treated with 59 fixed partial dentures (FPD) of different types and 84 full crowns on natural teeth. The Zirconia frameworks were CAM fabricated (Cercon Smart Ceramics) and veneered with a glass-ceramic material (Cercon Kiss) in layering technique. Luting protocol was matched to restoration type: conventional or adhesive. Clinical follow-up examinations consisted of a complete dental and hygiene status and a clinical quality assessment according to modified CDA criteria. Due to loss to follow up of 4 patients, 138 restorations were investigated. For evaluation, they were assigned to a “standard design” (st-dn, crowns and 3 to 4 unit bridges; NSt=103) and a “special design” group (sp-dn, crown blocks, multi-unit, cantilever or partial crown-retained FPDs; NSp=35).
Results: Within an observation time of 85 months (range: 4 to 85, mean 24, median 17 months), 28 reconstructions (10 of 35 sp-dn, 18 of 103 st-dn) experienced a complication (Pc=19.6%) affecting 16 patients. But, only 4 patients accounted for barely half the complications. The complication rate was estimated at 0.24 (sp-dn) and 0.19 (st-dn) within 24 months. Technical complications of the veneering on posteriors (n=19 plus 1 anterior) were predominant, followed by endodontic problems (n=4) and loss of retention (n=4). Seven of these complications were assessed as clinical failures, resulting in a survival estimate of 0.96 over 24 months for all reconstructions. Three of these failed restorations are still in service.
Conclusion: Zirconia-based restorations showed adequate overall clinical survival, even such with special design features. Nevertheless, clinical performance was still compromised by technical complications of the veneering ceramic, especially on posterior restorations.