Effect of acidic drinks on shade matching, surface topography, and mechanical properties of conventional and bulk-fill composite resins

Statement of problem. Posterior composite restorations may be negatively affected by acidic and colored drinks. Little information is available about the effect of acidic drinks on bulk-fill composite resins. Purpose. The purpose of this in vitro study was to investigate the effect of acidic drinks on the different properties of conventional and bulk-fill composite resins. Material and methods. A conventional composite resin and 2 representative bulk-fill composite resins were used to prepare disk-shaped specimens. The degree of conversion (DC) was monitored by spectroscopy (n= 5). The specimens were divided into 5 groups: control, artificial saliva, acai juice, red wine, and Coca-Cola and were maintained for 30 days of challenge (3 periods of 15 min/d). Surface topography parameters were measured by interferometry (n= 5). Elastic modulus (E) and Vickers hardness (VH) were determined by microhardness dynamic indentation (n= 5). Diametral tensile strength (DTS) was determined at 0.5 mm/min (n= 5). Shade matching was evaluated by using the Vitapan Classic Shade Guide. The DC, Sa, Ssk, Sku, Sdq, and DTS were statistically analyzed using 2-way ANOVA, followed by the Tukey HSD tests. E and VH were statistically analyzed by 3-way ANOVA, followed by Tukey HSD tests (alpha=. 05). Shade matching was analyzed with the Kruskal-Wallis test. Results. DC values were similar for the immediate evaluation and after 24 hours, regardless of the composite resin (P<.05). All surface topography parameters increased significantly after the acidic drinks and were greatest for Coca-Cola. The E, VH, and DTS decreased significantly for all composite resins tested (P<.05). Acai juice and red wine produced more surface staining than Coca-Cola. Conclusions. Acidic drinks negatively influenced the physical and mechanical properties of conventional and bulk-fill composite resins.