Effect of Beverages on the Surface Properties of Bulk-Fill Composites

Objectives: The aim of this study was to evaluate effect of acidic beverages on the hardness(H), elastic modulus(EM) and wear resistance(WR) of resin composites.
Methods: A total of 96 specimens (10mm-diameter, 4mm-thickness) were prepared from 3 composites: Beautifil Bulk Restorative(BBR), Tetric N-Ceram Bulk Fill(TNC), Filtek Z250(Z250). Each composite group was divided into 4 subgroups (n=8) according to the storage media: artificial saliva(control), orange juice, coke, sport drink. Experimental specimens were immersed in the solutions for 30 minutes, 5x/day for 5 days and kept in artificial saliva for an hour between the erosive periods. Control specimens were stored in artificial saliva for 5 days. Nanoindentation test with a Berkovich diamond tip was used to determine the H and EM of the specimens before and after the 5-day storage periods. Following the nanoindentation tests, the specimens were subjected to a chewing simulator for 120 000 loading cycles. The specimens were scanned with a three dimensional scanner. The WR was analyzed by measuring the volume and height loss. Specimens were observed by environmental scanning electron microscope. The statistical analyses were performed by Two-Way ANOVA, Tukey HDS test and Paired Samples t test(p<0.05).
Results: Z250 showed significantly higher H and EM in all groups(p<0.05). After erosive cycles, the most intense decrease on H and EM was observed for BBR. TNC showed higher WR than Z250 and BBR(p<0.05).
Conclusions: Different composition and percentage of the filler particles resulted in different wear patterns among the materials. It seems that Pre-polymerized particles within the composition of TNC, protected the surface from excessive wear.