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Introduction

Resin-based composites have been used extensively as direct dental restorative materials due to their good esthetic properties and long-lasting clinical performance. Several industry manufacturers offer a wide range of resin composite materials for use in both anterior and posterior areas. Current differences among materials are mainly related to their inorganic filler components, which might affect their handling characteristics and physical properties , ultimately influencing the clinical service of restorations . It is known that well-dispersed inorganic particles in a resin matrix effectively improve the polymer strength . Therefore, dental composites have usually been classified according to their filler characteristics, especially particle size.

Numerous adjustments in filler characteristics–most recently, the introduction of nano- and submicron-sized particles–have been proposed in an endeavor to provide a material with high initial polishing combined with superior polish and gloss retention. It is a general belief that smaller filler particles protect the softer resin phase from wear and reduce surface alterations resulting from loss of particles. The size of the fillers is usually ascribed to having a significant impact on composites’ surface properties, such as smoothness and gloss . In the same way, appearance and surface luster are often related to clinical performance of restorations, especially in anterior teeth. There is no clinical evidence, however, that nanofill or submicron restoratives show better performance compared to microhybrids regarding restorations’ esthetic and surface qualities.

Despite manufacturers’ efforts in development and marketing of new materials, the question still remains whether clinicians should consider using nanofill or submicron composites over traditional microhybrids. This question cannot be indisputably answered based on the scarce clinical evidence available; however, in vitro evaluations on the surface characteristics of nanofill and submicron resin-based restoratives are abundant in the literature. Several studies have addressed the effects that challenges such as toothbrushing, thermal cycling, or pH cycling may have on the surface properties of composites. In vitro investigations have the shortcoming of employing different finishing and/or polishing procedures, or distinct methods to evaluate surface properties of the composites, sometimes hindering comparisons among studies or materials.

The aim of this study was to systematically review the literature to gather information on how nanofill and submicron dental composites react to finishing/polishing procedures and surface challenges in vitro , compared with traditional microhybrids regarding surface characteristics. The hypothesis tested was that there is no laboratory evidence to support the choice of nanofill or submicron composites over traditional microhybrid materials based upon better performance regarding surface properties.