Do nanofill or submicron composites show improved smoothness and gloss? A systematic review of in vitro studies

OBJECTIVES: Despite nanofill and submicron composites' aim to provide high initial polishing combined with superior smoothness and gloss retention, the question still remains whether clinicians should consider using these new materials over traditional microhybrids. The aim of this paper was to systematically review the literature on how nanofills and submicrons react to polishing procedures and surface challenges in vitro compared with microhybrids. The paper has also given an overview of the compositional characteristics of all resin composites and polishing systems whose performance was presented herein. DATA: The database search for the effect of filler size on surface smoothness and gloss of commercial composites retrieved 702 eligible studies. After deduplication, 438 records were examined by the titles and abstracts; 400 studies were excluded and 38 articles were assessed for full-text reading. An additional 11 papers were selected by hand-searching. In total, 28 articles met inclusion criteria and were included in the study. SOURCES: The databases analyzed were MEDLINE/PubMed, ISI Web of Science, and SciVerse Scopus. STUDY SELECTION: Papers were selected if they presented a comparison between nanofill or submicron and microhybrid composites with quantitative analysis of smoothness and/or gloss on baseline and/or after any aging protocol to assess smoothness and gloss retention. Only in vitro studies written in English were included. CONCLUSIONS: There is no in vitro evidence to support the choice for nanofill or submicron composites over traditional microhybrids based on better surface smoothness and/or gloss, or based upon maintenance of those superficial characteristics after surface challenges