Nanohybrid versus nanofill composite in class I cavities: Margin analysis after 12 months

This study evaluates the margin of a nanofill, a nanohybrid, and a conventional microhybrid composite in restorations in occlusal cavities of posterior teeth after 12 months. Forty‐one patients, each with three molars affected by primary caries or the need to replace restorations, participated in this research. The teeth were restored with a nanofill (Filtek Z350), a nanohybrid (Esthet‐X), and a microhybrid as a control (Filtek Z250). Ten patients were selected randomly, and the three restorations were molded with a low‐viscosity polyvinyl siloxane material. The molds were poured with epoxy resin, gold‐sputter coated, observed by scanning electron microscopy, and classified as: “perfect margin,” “marginal irregularity,” “marginal gap,” “marginal fracture,” or “artifact.” For statistical analysis, the Wilcoxon and Friedman nonparametric tests and paired‐samples t‐test were used (significance level of 5%). The performance of the three materials was compared after 1 week and 12 months. No statistically significant differences were detected for all criteria (P > 0.05). When each composite was compared over time, statistically significant differences were found for the criterion, perfect margins (Esthet‐X and Filtek Z350, P < 0.05). The materials performed satisfactorily over the 12‐month‐observation period, but all composites under investigation showed a certain amount of deterioration relating to marginal quality over time. Microsc. Res. Tech. 74:23‐27, 2011. © 2010 Wiley‐Liss, Inc.