Purpose: This controlled clinical trial aimed to evaluate IPS Empress inlays and onlays over 12 years. The null hypothesis was that different luting resins would have no influence on clinical outcome. Materials and Methods: In the course of a prospective clinical long-term trial, 96 ceramic inlays and onlays were placed in 34 patients using one adhesive (Syntac) and four different luting composites (Tetric, Variolink Low, Variolink Ultra, Dual Cement). Recalls were carried out by two calibrated investigators using modified USPHS codes and criteria at baseline, 1, 2, 4, 6, 8, and 12 years. Results: Fifteen of the 96 restorations had to be replaced (failure rate 16%; Kaplan-Meier); 12 of them suffered bulk fractures. After twelve years of clinical service, significantly more bulk fractures were found when light-curing composite was used for luting (p 0.05). Fractures were noticed between 3 and 4 years of clinical service and later after 11 to 12 years; aside from those times, no single fracture occurred. Secondary caries was not observed. Conclusion: IPS Empress inlays and onlays exhibited satisfactory clinical outcomes over a 12-year clinical period. Restorations luted with dual-cured resin composites revealed significantly fewer bulk fractures. Schlagwörter: ceramics, resin composites, luting, dual-curing, dentin bonding, clinical trial