Effects of Polishing Systems on Thermocycled and Coffee-Immersed Composite Resins

Objectives: Aging alters composite resin properties such as roughness, color stability, and microhardness, while polishing systems determine clinical performance and longevity. This study evaluated the effects of aging on surface properties of five composite resins polished with four different polishing systems. Materials and Methods: Surface roughness, color, and microhardness were assessed at different stages (control, after polishing, and after aging). Surface topography was analyzed by Atomic Force Microscopy (AFM) and Scanning Electron Microscopy (SEM) before (control) and after aging. The samples were subjected to thermal cycling (10,000 cycles between 5-55°C) and immersion in coffee solution. Results: Aging significantly increased roughness and color change while reducing microhardness across all groups. OneGloss produced the highest roughness values, whereas multi-step polishing systems (Zenit Flex, Clearfil TwistDia, Nova Twist) achieved superior surface quality. Clearfil Majesty ES-2 consistently showed higher roughness due to its composition. Clinically unacceptable color shifts occurred after aging, particularly in Filtek Ultimate Universal. Zenit Flex improved microhardness in Palfique Estelite Paste and Filtek Ultimate Universal, while Clearfil TwistDia reduced roughness in Clearfil Majesty ES-2. Conclusions: Aging negatively affected all surface properties of composite resins. Multi-step polishing systems demonstrated better clinical performance compared to single-step systems. The selection of polishing systems should be based on the specific composite resin type to achieve optimal long-term clinical outcomes.