Marginal and Internal Misfit of Occlusal Veneers Made in Resin-matrix Ceramics.

Abstract

Considering that misfit is a significant predictor of the clinical success of indirect restorations, the objective of this study was to evaluate the marginal and internal misfit of two computer-aided design and manufacturing (CAD/CAM) RMC ceramic materials used as occlusal veneers (OVs) of different thicknesses. A CAD model of a mandibular first molar was obtained and OV preparations 0.5-, 1.0-, and 1.5-mm thick were modeled and milled in two different materials (n=10/group): resin nanoceramic (RNC) and polymer-infiltrated ceramic network (PICN). Using the same CAD model, tooth preparations were milled in fiber-reinforced epoxy resin (n=20/thickness). The marginal and internal misfit of the restorations was assessed by X-ray microtomography. The measurements of the marginal gap (MG) and absolute marginal discrepancy were performed in two locations on each slice, whereas internal gap (IG) measurements were performed at ten locations on each slice. The data obtained were analyzed using two-way analysis of variance and Tukey post-hoc tests (α=0.05). No significant effect was attributable to the material type or material-thickness interaction for the MG, absolute marginal discrepancy (AMD), or IG (p>0.05). However, the thickness significantly affected the IG of the restorations (p<0.05). CAD/CAM RNC and PICN systems presented similar MG and AMD for OVs 0.5-, 1.0-, and 1.5-mm thick. However, the IG varied between thicknesses.