Marginal integrity of partial ceramic crowns within dentin with different luting techniques and materials.
This in vitro study evaluated the marginal integrity of partial ceramic crowns (PCCs) luted with or without a resin-coating and compared the results with the marginal sealing of a recently introduced self-adhesive universal resin cement. PCC preparations were performed on 84 extracted human molars, with proximal margins placed 1 mm below the cemento-enamel junction. The PCCs were fabricated from Vita Mark II ceramic (Vita) using the Cerec-3 Unit (Sirona). The prepared teeth were assigned to three groups: (1) conventional luting technique (n=36), (2) resin-coating luting technique (n=36) or (3) recently introduced self-adhesive universal resin cement (n=12). Within these three groups, the following materials were applied: (1) Excite/Variolink II (EVC), ED-Primer/Panavia-F2.0 (PAC), Syntac Classic/ Variolink II (SYC); (2) Excite/Variolink II with Excite/Tetric Flow resin-coating (EVR), ED-Primer/Panavia-F2.0 with Clearfil SE-Bond/ Protect-Liner F resin-coating (PAR), Excite/ Variolink II with Syntac Classic/Tetric Flow resin-coating (SYR); (3) RelyX Unicem (REX). After thermocycling and mechanical loading (TC: 5000 cycles at 5 degrees C/55 degrees C; 30 seconds/cycle; ML:500000 cycles at 72.5 N, 1.6 Hz), microleakage was assessed by evaluating silver staining (%) on multiple tooth sections. Ceramic/composite-, resin-coating/composite- (where applicable) and dentin/composite-interfaces were evaluated separately. The data were statistically analyzed with the Mann-Whitney-U-test and the Error Rates Method. In Groups 1 and 2, the evaluation of microleakage at dentin showed better marginal integrity when the resin-coating technique was applied (EVR, PAR, SYR: 18-53%) than within the conventional luting technique group (EVC, PAC, SYC: 58-67%). However, the lowest microleakage values were found for RelyX Unicem (REX: 15%). In conclusion, resin-coating may improve the marginal sealing within dentin, depending on the materials used. Luting with a self-adhesive universal resin cement showed the best marginal sealing of all groups.