Influence of Self-Adhesive Resin Composite Deep Marginal Elevation on the Sealing Ability of CAD/CAM Lithium...

Deep margin elevation (DME) is a conservative technique used to relocate subgingival proximal margins to a more favorable supragingival position, facilitating adhesive procedures and impression taking. This in vitro study evaluated the influence of two DME materials-a universal flowable resin composite and a self-adhesive flowable resin composite-on the cervical interfacial sealing ability of lithium disilicate glass-ceramic CAD/CAM inlay restorations. Twenty extracted maxillary premolars were randomly allocated into two groups (n = 10). Group A received DME using a universal flowable resin composite (3M™ Filtek™ Z350 XT) preceded by a conventional adhesive system, while Group B received DME using a self-adhesive flowable resin composite (Vertise™ Flow). All teeth were restored with lithium disilicate CAD/CAM inlays (CEREC Tessera) cemented with a self-adhesive resin cement (Breeze^®). Specimens underwent thermocycling (10,000 cycles; 5-55 °C). Marginal gaps were assessed at the DME interface using high-resolution micro-computed tomography (micro-CT) in both coronal and sagittal cross-sections, before and after thermocycling. Statistically significant differences were found between groups in both sections before and after thermocycling (p < 0.05). The self-adhesive composite (Group B) demonstrated significantly lower gap values compared to the universal flowable composite (Group A) in both coronal and sagittal assessments. Thermocycling increased the gap in both groups; however, Group B maintained considerably lower leakage. The self-adhesive resin composite showed superior sealing ability at the DME interface compared to the universal flowable composite when used under lithium disilicate glass-ceramic inlay restorations. Further clinical studies are recommended to validate these findings.