Performance of composite resins in direct restorations of anterior teeth

a literature review

Abstract

Introduction / Justification: Dental aesthetics plays a fundamental role in self-esteem and social interactions, being considered an important determinant of patients' quality of life. In this context, direct restorations in anterior teeth represent a widely used therapeutic alternative for correcting aesthetic and functional alterations, such as fractures, diastemas, and changes in tooth shape or color.

Among the available restorative materials, composite resins have stood out for their clinical versatility, favorable aesthetic properties, and relative ease of manipulation. Since their introduction into restorative dentistry, these materials have undergone significant technological evolutions, especially related to the composition of the organic matrix, the size and distribution of filler particles, and the optical and mechanical stability of the materials.

Currently, several classes of composite resins are available on the market, including microhybrid, nanoparticulate, and nanohybrid resins, each presenting specific characteristics related to mechanical resistance, polishability, color stability, and clinical durability. However, despite the large number of commercially available materials, there is still debate in the scientific literature about the comparative performance of these resins and their clinical predictability in anterior restorations. Therefore, it becomes relevant to critically analyze the available scientific evidence on the aesthetic and functional properties of composite resins used in direct anterior restorations, in order to assist the dentist in choosing the most appropriate materials for clinical practice. Objectives: To evaluate, through a literature review, the composite resins currently available for direct restorations in anterior teeth, analyzing their aesthetic and functional properties, as well as the main parameters used to assess their clinical and laboratory performance. Methodology: A literature review was conducted using the PubMed, Web of Science, and Scopus databases. The search strategy was conducted in April 2025 using the descriptors: "Composite resin AND Direct AND (Anterior OR incisor OR canine)". Only articles published in the last ten years (2015–2025) and written in English were considered. Initially, 943 articles were identified in the searched databases. After removing duplicates, the studies were evaluated by two independent researchers through the reading of titles and abstracts. Potentially eligible articles were subsequently analyzed in full, and only those that compared different commercial composite resins used in direct anterior restorations or that presented relevant results related to the aesthetic or functional performance of these materials were included. The following were excluded: narrative reviews, case reports, and studies that did not present a comparison between restorative materials. In case of disagreement between the reviewers, a third researcher was consulted for the final decision. At the end of the selection process, 19 articles were included in the analysis. The selected studies were organized into spreadsheets containing information such as author, year of publication, type of study, sample, parameters evaluated, methodology used, and main results obtained. Results: Analysis of the included studies revealed that 34 different commercial composite resins were evaluated in the selected research. Among them, nanohybrid and nanoparticulate resins were the most frequently investigated, reflecting the current preference for materials that combine adequate mechanical properties and better aesthetic performance. The parameters most frequently analyzed in the studies were: color stability, surface roughness, wear resistance, gloss retention, marginal adaptation, microleakage. Several laboratory studies have demonstrated that the size of the filler particles directly influences the surface smoothness and polishability of the resins, with materials with smaller particles tending to present more homogeneous surfaces and greater gloss retention. Regarding color stability, it was observed that different materials exhibit distinct behaviors when exposed to pigmenting agents, such as coffee and tea. Some studies indicated greater color stability in injectable or nanoparticulate resins when compared to conventional materials. Clinical studies included in the review demonstrated satisfactory survival rates for anterior restorations performed with composite resins, often exceeding 90% in follow-up periods of up to four years. However, failures related to fractures, marginal color change, and surface wear can still occur over time. In general, the results indicate that the performance of composite resins depends not only on the material class but also on the brand, chemical composition, and clinical protocol used. Conclusion: Contemporary composite resins offer satisfactory performance for direct restorations in anterior teeth, providing adequate aesthetic and functional results in most clinical situations. However, no absolute superiority of a specific resin class over others was observed, since the performance of the materials depends on multiple factors, including material composition, restorative technique, and individual clinical conditions. Thus, the choice of restorative material should consider not only the physical-mechanical properties of composite resins but also the professional's clinical experience and the specific characteristics of each case.