Margin Analysis of Different Restoration Methods for Deep Class-II Cavities

Objectives: Aim of this in vitro study was to compare the proximal marginal quality of direct composite restorations, CAD/CAM ceramic inlays, and composite inlays according to a visual assessment.
Methods: Sixty standardized class II MOD cavities with two proximal boxes extending 1.5 mm below the cemento enamel junction were prepared in extracted human molars which were placed in modified phantom models (KaVo). The cavities were randomly assigned to three groups (n=20 each).
Cavities in group I were restored with indirect composite inlays (GrandioSO) extraorally fabricated on a silicone model (Die silicone). Cavities in group II were restored with CAD/CAM ceramic inlays (Cerec 3D, IPS Empress CAD) and in group III with incrementally layered direct composite (GrandioSO). All Inlays were luted with a dual-curing resin cement (Bifix QM).
After finishing and polishing, the cervical margins were visually and tactilely evaluated using a dental probe (DA458R): MQ1: perfect margin (score 0), MQ2: overhang/negative step < 1/3 margin length (score 1), MQ3: overhang/ negative step < 2/3 margin length (score 2), MQ4: overhang/ negative step > 2/3 margin length (score 3), MQ5: complete marginal overhang/ negative step (score 4). Kruskal-Wallis-Test and Mann-Whitney-U-Test served for statistical analysis (p < 0.05).

Results: The sum score (MQ1-MQ5; median, 1^st and 3^rd quartile) was 19.5 (14.5-24) for group I, 11.50 (8.25-16) for group II, and 12 (6.25-16) for group III. Results were statistically significant different between group I and group II as well as between group I and group III, but not between group II and III.
Conclusions: Within the limitation of this study, the results show that CAD/CAM inlays and direct composite restorations provide better cervical marginal quality than the indirect composite inlay system.