Objectives:
This study evaluated the long-term clinical performance and survival of CAD-CAM-fabricated partial ceramic crowns (PCCs) luted with either self-adhesive resin cement, or conventional luting composite combined with a universal adhesive, applied without or with selective enamel etching.

Methods:
A 12 year follow-up of a randomized split-mouth clinical trial initially including 48 patients was conducted. PCCs were luted with three different randomized luting protocols (all material: Solventum): RXU (RelyX Unicem), SBU-E (RelyX Ultimate/Scotchbond Universal, no selective enamel etching), SBU+E (RelyX Ultimate/Scotchbond Universal, with selective enamel etching). Clinical performance was assessed using FDI criteria at baseline and after 12 years. Survival rates were calculated using Kaplan-Meier analysis, and statistical differences between groups and over time were tested using Chi-square and log-rank tests (α=0.05).

Results:
After a median observation period of 12.2 years, 16 patients (38 restorations) were available for clinical evaluation. By including information from files of patients that were not available for clinical evaluation, the Kaplan-Meier survival analysis included 35 patients (87 restorations). The survival rates significantly differed between the groups: RXU (36.4 %), SBU-E (60.7 %), and SBU+E (80.8 %). RXU demonstrated significantly lower survival compared to both SBU-E (p = 0.034) and SBU+E (p = 0.001), while no significant difference was observed between SBU-E and SBU+E (p = 0.141). Clinical performance evaluated according to FDI criteria remained acceptable for all groups and criteria at 12 years, with mostly minor aging-related changes observed, e.g. in terms of a significant increase in marginal staining (p ≤ 0.002) for all groups and a significant deterioration in marginal adaptation for RXU (p = 0.009) and SBU-E (p = 0.003) over time. PCCs placed with a universal adhesive and conventional luting composite combination showed a significantly higher survival compared to PCCs placed with self-adhesive resin cement. Selective enamel etching by tendency improved the performance of the conventional luting composite.

Significance:
The study highlights the importance of adhesive protocols in achieving long-term survival and clinical success for PCCs, particularly emphasizing the benefits of universal adhesives without or with selective enamel etching combined with luting composites.