Monolithic Polymer-Infiltrated Ceramic Network CAD/CAM Single Crowns: Three-Year Mid-Term Results of a Prospective Clinical Study

Purpose: To evaluate the clinical outcomes of monolithic CAD/CAM–fabricated polymer-infiltrated ceramic network (PICN) single crowns (SC) after 3 years. Materials and Methods: A total of 34 patients who received 76 single crowns were included in this cohort study. Full-coverage crown preparation with reduced thickness (1.0 to 1.5 mm) was applied. All monolithic PICN SCs (VITA Enamic) were manufactured using a CAD/CAM system and adhesively seated. Clinical follow-up evaluations were performed at 6, 12, 24, and 36 months after insertion using modified United States Public Health Service (USPHS) criteria. Kaplan-Meier survival and success methods were applied to calculate absolute and relative failures. To determine effects of time and restoration, a mixed logit model was adjusted for the modified USPHS criteria (P .05). Results: PICN SCs revealed an estimated Kaplan-Meier survival rate of 93.9% after 3 years. Four clinically unacceptable fractures occurred, which resulted in replacement of the affected SCs. Neither secondary caries nor debonding were recorded. The 3-year Kaplan-Meier success rate was 92.7%. Significant increases in marginal discoloration (P = .0002) and surface roughness (P .0001) were noted over time. Color match, anatomical form, and marginal adaptation remained favorable over the given observation period. Conclusion: PICN CAD/CAM crowns with reduced thickness showed acceptable survival and success rates over a service time of 36 months. However, extended clinical follow-up periods are needed to evaluate the long-term performance.