Margin Assessment And Fracture Resistance Of Adhesively Luted Ceramic Crowns

Objectives: The aim of this study was to investigate the effect of different adhesive systems on the vertical marginal gap distance and the fracture resistance of lithium disilicate based crowns. Methods: Forty premolars were prepared to receive forty e-max crowns. The crowns were divided into 4 groups (N=10 each) according to the adhesive luting systems. Group (U): using RelyX Unicem resin cement (self-adhesive system). Group (V): Variolink II (total-etch system). Group (GU) and group (GV): application of G-bond (self-etch) on dentin preceded previously used adhesive systems. A stereomicroscope was used to record the vertical marginal gap distance before and after cementation. The crowns were subjected to cyclic loading and fracture resistance test. Data were statistically analyzed using One-way Analysis of Variance (ANOVA) SPSS 15.0. A scanning electron microscope was used to qualitatively examine the dentin/resin interface. Results: groups (GU) (67.6 ± 5.8 µm) and (GV) (68 ± 6.4 µm) recorded the significantly lowest vertical marginal gap, followed by group (V) (82 ± 6.8 µm). Group (U) showed the highest marginal inaccuracy (114 ± 6.4 µm). Group (GU) recorded the significantly highest fracture resistance (2840.5 ± 3.8 N), followed by group (GV) (2411.3 ± 3.3 N) and group (V) (2365.8 ± 3.6 N). Group (U) showed the lowest results (2270.9 ± 3.4 N). Conclusions: Ceramic restorations luted with total-etch system offer better vertical marginal gap distance and fracture resistance than restorations luted with self-adhesive system. Treatment of the dentin surface prior to the application of the bonding system is efficient.