Controlled, prospective, randomized, clinical evaluation of partial ceramic crowns inserted with RelyX Unicem with or without selective enamel etching. 1-year results.

Purpose: To compare the performance of partial ceramic crowns (PCCs) inserted with RelyX Unicem (RXU) either with (RXU+E) or without (RXU) selective enamel etching.

Methods: 34 patients (15 male, 19 female) participated in the investigation, with a total of 68 PCC restorations. In each patient, one PCC was randomly assigned to insertion with RXU, the second PCC was assigned to insertion with RXU+E. The PCCs were CAD/CAM fabricated using the Cerec 3 system. RXU: 25 PCCs were placed in molars, nine in premolars. RXU+E: 26 PCCs were placed in molars, eight in premolars. The restorations were clinically rated using modified United States Public Health Service (USPHS) criteria at baseline, 6 and 12 months after placement. The median patient age was 41 years (24-59 years). The median (25-75%) PBI was 6% (3-9%).

Results: All patients were available for the three recall appointments. One PCC (RXU) debonded after 11 months in situ, one PCC (RXU+E) fractured after 12 months in situ. Both restorations had to be replaced. At the 12 months recall, 66 of 68 controlled restorations were functional without need of replacement. The evaluation using USHPS criteria revealed a significant decrease of alfa ratings over time with respect to criteria marginal adaptation and marginal discoloration. No statistically significant differences between the two luting techniques, RXU and RXU+E, we reobserved during the observation period of 1 year. Within the limitations of the present study, adhesive luting with RXU with or without selective enamel etching can be recommended.