Physical and Mechanical of Conventional and Bulk-fill Composite Resins

Objectives: The objective was to investigate the influence of acidic drinks on different properties of conventional and bulk-fill composite resins.
Methods: One conventional composite resin (Z350) and two bulk-fill composite resins (TNC and X-TRA) were used to prepare specimens. The degree of conversion (DC) was monitored using Spectroscopy (FTIR) (n = 5). The specimens were divided into 4 groups: artificial saliva, acai juice, red wine and Coca-Cola. Specimens were maintained for 30 days of challenge (3 times of 15 minutes/day). Surface topography analysis was performed using 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 using the Vitapan Classic Shade Guide. The surface roughness parameters, E, VH and DTS were statistically analyzed using two-way ANOVA and Tukey's test (∝ = 0.05). Shade matching was analyzed using the Kruskal-Wallis's test.
Results: DC were similar during immediate and after 24 hours evaluations, regardless of the composite (P < 0.05). The E, VH and DTS decreased significantly for all composite resins tested (P < 0.05). Surface roughness increased significantly after the acidic drinks, mainly in Coca-Cola. 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. Bulk-fill composite resins had similar performances compared with conventional composite resins for all parameters.