Does Finishing and Polishing of Restorative Materials Affect Bacterial Adhesion and Biofilm Formation? A Systematic Review.

Biofilm (bacterial plaque) accumulation on the surface of restorative materials favors the occurrence of secondary caries and periodontal inflammation. Surface characteristics of restorations can be modified by finishing and/or polishing procedures and may affect bacterial adhesion. The aim of this systematic review was to characterize how finishing and polishing methods affect the surface properties of different restorative materials with regard to bacterial adhesion and biofilm formation. Searches were carried out in MEDLINE-PubMed, EMBASE, Cochrane-CENTRAL, and LILACS databases. From 2882 potential articles found in the initial searches, only 18 met the eligible criteria and were included in this review (12 with in vitro design, four with in situ design, and two clinical trials). However, they presented high heterogeneity regarding materials considered and methodology for evaluating the desired outcome. Risk bias analysis showed that only two studies presented low risk (whereas 11 showed high and five showed medium risk). Thus, only descriptive analyses considering study design, materials, intervention (finishing/polishing), surface characteristics (roughness and surface free energy), and protocol for biofilm formation (bacterial adhesion) could be performed. Some conclusions could be drawn: the impact of roughness on bacterial adhesion seems to be related not to a roughness threshold (as previously believed) but rather to a range, the range of surface roughness among different polishing methods is wide and material dependent, finishing invariably creates a rougher surface and should always be followed by a polishing method, each dental material requires its own treatment modality to obtain and maintain as smooth a surface as possible, and in vitro designs do not seem to be powerful tools to draw relevant conclusions, so in vivo and in situ designs become strongly recommended.