Abstract
The surface properties of composite resin restorative materials are critical for the esthetics and longevity of restorations. This in vitro study evaluated the microhardness change and surface roughness change in four resin composites recommended for anterior restorations after two aging simulations: thermal cycling (10,000 cycles) and one year of water storage. Ten specimens (n = 10) were prepared for each material. After baseline measurements, samples were subjected to one of the aging procedures, and surface properties were reassessed. For microhardness change (∆H), significant differences were observed among materials under both thermal cycling (p = 0.001) and water storage (p = 0.001). Omnichroma-thermal cycling showed a greater decrease than G-ænial Anterior (p = 0.028) and Clearfil Majesty ES-2 (p = 0.001), while Optishade-thermal cycling decreased more than Clearfil Majesty ES-2 (p = 0.015). In water storage, Omnichroma exhibited a greater decrease than Optishade (p = 0.042) and Clearfil Majesty ES-2 (p = 0.001), and G-ænial Anterior decreased more than Clearfil Majesty ES-2 (p = 0.026). Optishade and Clearfil Majesty ES-2 showed significantly greater decreases after thermal cycling than water storage, while Omnichroma and G-ænial Anterior showed no difference. For the change in surface roughness (∆R), significant differences were also found (p = 0.001). In thermal cycling, Optishade exhibited the lowest increase, while G-ænial Anterior showed the highest. In water storage, G-ænial Anterior again had the highest increase, significantly greater than all others (p = 0.001). For all materials, ∆R values were significantly higher after thermal cycling compared with those in water storage (p = 0.001). These results demonstrate that both composite type and aging method influence long-term surface properties. Overall, thermal cycling exerted more detrimental effects than water storage.