Time-dependent surface roughness changes in nanohybrid composite resins exposed to whisky and beer: an in vitro study

Objective: To evaluate the effect of whisky and beer on surface roughness and to compare the time-dependent behavior between two nanohybrid composite resins in a 14-day in vitro model. Methods: A total of 240 resin discs (7x3 mm) were divided into six groups (n=40 per group) according to the type of resin (Tetric® N-Ceram and Filtek™ Z250 XT) and the immersion medium (artificial saliva, Ballantine’s Finest® whisky, and Pilsen Callao® beer). Immersions were carried out following a structured protocol: four immersions per day for five days, followed by two days of storage in artificial saliva. Surface roughness was measured at baseline, and on days 7 and 14 post-experiment. Data were analyzed using the Kruskal-Wallis test (P<0.05). Results: Surface roughness increased in both resins after alcoholic exposure (P<0.001); however, distinct time-dependent patterns were observed. Tetric® N-Ceram showed an early increase, particularly in beer at 7 and 14 days (P<0.05), while Filtek™ Z250 XT exhibited a progressive increase over time, especially under whisky exposure, with significant changes observed from 24 hours onward (P<0.05). Conclusion: Filtek™ Z250 XT resin showed a greater increase in surface roughness with longer exposure times to both alcoholic beverages, whereas Tetric® N-Ceram exhibited a more pronounced increase at earlier stages. These findings highlight the importance of considering time-dependent material behavior when evaluating the durability of composite restorations under chemical challenges.