Deep Margin Elevation With Various Resin Composites: Effect of Thermomechanical Aging on the Marginal Gap of CAD / CAM Inlays

ABSTRACT

Objective
This in vitro study evaluated the effects of composite material type, margin design (deep margin elevation vs. control), and thermomechanical aging on the marginal gap of CAD/CAM inlay restorations.


Materials and Methods

Standardized mesio‐occluso‐distal (MOD) inlay cavities were prepared in extracted human molars, with mesial margins located at the cemento‐enamel junction (control) and distal margins extended 2 mm apical to the CEJ and elevated using three resin composite materials (bulk‐fill, packable, and flowable). CAD/CAM inlays were fabricated and luted. Marginal gap values were measured using scanning electron microscopy at baseline and after thermomechanical aging simulating 1 year of clinical service. Data were analyzed using mixed repeated‐measures ANOVA to evaluate the effects of material type, margin design, aging condition, and their interactions (
α
 = 0.05).



Results

Thermomechanical aging significantly increased marginal gap values (
p
 < 0.001). Margin design showed a significant effect (
p
 = 0.015), whereas the main effect of material type was not statistically significant (
p
 = 0.205). Significant interactions were observed between material type and margin design (
p
 = 0.008) and among material type, margin design, and aging condition (
p
 < 0.001).



Conclusions
Within the limitations of this current study, thermomechanical aging significantly increased marginal gap values of CAD/CAM inlays. Material type alone did not show a significant main effect on marginal gap. However, significant interaction effects were observed between material type and deep margin elevation, as well as between material type and aging condition.