Veneered anatomically designed zirconia FDPs resulting from digital intraoral scans: Preliminary results of a prospective clinical study.

OBJECTIVES: The aim of this prospective clinical study was to evaluate the clinical performance of veneered anatomically designed zirconia fixed dental prostheses (FDPs) resulting from intraoral digital impressions. METHODS: 24 patients requiring treatment were provided with all-ceramic FDPs. Intraoral scans (iTero) were performed and veneered anatomically designed CAD/CAM-zirconia FDPs (Zerion/VitaVM9) were fabricated. A feldspar veneering ceramic following a slow cooling firing protocol was applied. A self-curing resin based luting material was used for adhesive cementation. Clinical evaluations were performed at baseline and 6, 12, and 18 months recalls according to the modified USPHS-criteria. Intraoral digital surface scans (iTero) were performed at each recall examination and were digitally superimposed (Geomagic) to evaluate potential veneer cohesive fractures. Kaplan-Meier survival analysis comprised secondary caries, clinically unacceptable fractures, root canal treatment and debonding. Kaplan-Meier success rate included restorations with minimal crevices, tolerable color deviations and clinically acceptable fractures. Data were statistically analyzed. RESULTS: The Kaplan-Meier survival rate and success rate of the FDPs were 100% and 91.7%, respectively. Clinically acceptable veneer cohesive fractures and crevices at the restoration margin were observed in two patients. These shallow veneer fractures were only detected by overlapping baseline and recall scans. Ceramic surface roughness increased significantly over time (p<0.0001). CONCLUSIONS: Veneered zirconia FDPs fabricated from digital intraoral scans showed a favorable clinical performance over an observation period of 18 months. Anatomical zirconia core design and slow cooling firing protocol of the veneering ceramic reduced the incidence of chip fractures to a level that could not be detected clinically. CLINICAL SIGNIFICANCE: The digital workflow on the basis of intraoral digital impressions resulted in clinically satisfying outcomes for veneered zirconia FDPs.