Effect of different restorative systems and aging on marginal adaptation of resin composites to deep proximal margins

Objectives To evaluate and compare the marginal integrity of different restorative systems bonded to proximal gingival dentin, and determine the consistency level of the results obtained by two in vitro methods. Materials and Methods Thirty molars received occluso‐mesial preparations with dentin/cementum gingival margins. They were divided into three groups and restored using different restorative systems with light‐cured (Adhese Universal), self‐cured (Palfique universal bond), and dual‐cured (Futurabond U) adhesives. The restoration/gingival dentin interfaces were observed using scanning electron microscopy (SEM) and evaluated based on the World Dental Federation (FDI) criteria. After 10,000 thermal cycles, the marginal integrity was re‐evaluated. Marginal integrity was evaluated by the percentage of continuous margin (% CM) at ×200 for SEM and as the frequency of each score within the FDI ranking. Results No significant differences were found between the restorative systems immediately, however, the system with the light‐cured adhesive had the lowest marginal integrity after aging. All tested restorative systems were adversely affected by aging. A moderate inverse correlation was identified between evaluation techniques. Conclusion The tested restorative systems utilizing self‐cured and dual‐cured adhesives may be preferable for achieving optimal marginal integrity when bonding to deep proximal margins, compared to the tested system with light‐cured adhesive. Clinical Significance When performing deep margin elevation, it is important to consider the adhesive system being used.