Impact of dietary acids on the surface roughness and morphology of composite resins

This in vitro study was performed to evaluate the surface roughness (Ra) and morphology by scanning electron microscopy (SEM) of composite resins that had been stored in acidic solutions typical of those present in the diet. Three composite resins (4 Seasons, Z250, and P90) were selected and divided into three groups (n = 7) according to the solutions tested: G1: distilled water; G2, Coca-cola, and G3: orange juice. The Ra test was repeated after immersion periods of 15, 90, and 180 days. The mean Ra values were subjected to LS means analysis and the Tukey-Kramer (P < 0.05). One test specimen of each composite resin was selected for SEM analysis after each period. The Ra data indicated that P90 had the lowest Ra values. 4 Seasons and Z250 had statistically similar roughness values for all the solutions and evaluation periods. With the exception of 180-day immersion in Coca-cola, 4 Seasons showed significantly higher values than Z250. SEM analysis showed that P90 was the composite resin most resistant to the actions of all acid solutions for the periods analyzed. Interaction between components of the solutions and the active components of other dietary items, as well as oral hygiene, may affect the chemical degradation of composite resins.