Effect of deep margin elevation with resin composite and resin-modified glass ionomer on marginal sealing of CAD/CAM ceramic inlays: an in vitro study

Abstract

Purpose. To evaluate the marginal sealing ability of different restorative materials used in deep margin elevation (DME) on zirconia-reinforced lithium silicate CAD/CAM ceramic restoration. Methods. A total of 30 Class II cavities were prepared in freshly extracted human molars with the proximal gingival margin located 1 mm below the cemento-enamel junction (CEJ). All specimens were randomly assigned to one of three groups (n=10): control group, resin composite group (FiltekTM Z350 XT), and resin-modified glass ionomer group (VitremerTM Tricure). In group 1, control group, no DME was performed. The inlay margin of the control group was placed directly onto dentin. In groups 2 and 3, DME was used to elevate the margin to 1 mm above the CEJ with resin composite and resin-modified glass ionomer, respectively. Zirconia-reinforced lithium silicate CAD/CAM ceramic restorations were then bonded onto all specimens with a universal bonding and self-adhesive resin cement. All specimens were aged by water storage for 6 months. Marginal sealing ability at different interfaces was evaluated with a stereomicroscope at a 40x magnification by scoring the depth of silver nitrate penetration along the adhesive surfaces. Statistical differences between groups were analyzed using the Kruskal-Wallis and Mann- Whitney U tests. Results. At the dentin interface, there was no significant difference in microleakage scores in the control group and resin composite group (p = 0.577); however, the RMGI group had a significantly higher microleakage compared to the control group (p = 0.004) and resin composite group (p = 0.007). Conclusion. When DME is indicated, resin composite performed better as a DME material when compared to RMGI in terms of marginal sealing ability.