Influence of Irrigation on Polishing Protocols of Resin Composites: An In Vitro Study

This in vitro study evaluated the effect of irrigation on different polishing protocols and their influence on the surface roughness, microhardness, and mass of resin composites. Three resin composites (Admira® Fusion, Filtek Supreme™ XTE, and Ceram.X Spectra™ STHV) were polished using four systems (Sof-Lex™, DIATECH® ShapeGuard, Astropol®, and Enhance™/PoGo™) under wet and dry conditions. Eight test groups were established for each resin composite (n = 10 per group). Vickers microhardness, surface roughness (Ra), and specimen mass were measured before and after polishing with one of the four systems, applied either with or without irrigation. For Admira® Fusion polished with Sof-Lex™, Ra values were lower without irrigation (p = 0.048), whereas Filtek Supreme™ XTE and Ceram.X Spectra™ STHV polished with the Enhance™/PoGo™ system showed lower Ra values when irrigation was used (p = 0.010 and p = 0.004, respectively). Sof-Lex™ and DIATECH® ShapeGuard produced the highest microhardness values for both Admira® Fusion and Filtek Supreme™ XTE. Moreover, specimens of Admira® Fusion and Ceram.X Spectra™ STHV polished with DIATECH® ShapeGuard exhibited higher microhardness under irrigation (p = 0.048 and p = 0.027, respectively). Overall, polishing resulted in measurable material removal, reflected by a reduction in specimen mass, and in an increase in microhardness. Wet polishing generally increased microhardness, although the effect varied depending on the polishing system and resin composite. Clinicians should therefore consider both the resin composite and the polishing system when deciding whether to use irrigation, as appropriate irrigation control may help optimize the surface smoothness and microhardness of resin composite restorations. Conference Presentation: Preliminary data from this study were previously presented as an oral communication at the 32nd Portuguese Dental Association Annual Meeting. This manuscript represents a substantially expanded and revised version, developed as a full research article.