Effect of Mouthwashes on the Mechanical Properties and Color Stability of Composite Material

Interactions between the chemical compounds contained in mouthwashes and the components of dental composites may significantly influence their functional properties. The study investigated the effect of mouthwashes on the mechanical properties and color stability of a restorative nanocomposite. Twelve mouthwashes characterized by different chemical compositions were selected and distilled water was used as a control. Composite specimens were conditioned for 24 h, 48 h, and 72 h. Changes in microhardness (HV), compressive strength (CS) and diametral tensile strength (DTS) were evaluated. In addition, color changes were analyzed using spectrophotometric measurements. The results demonstrated a significant decrease in both HV and CS after exposure to mouthwashes, depending on their composition and immersion time. DTS values remained stable. Color changes were statistically significant; however, the values observed remained within clinically acceptable limits from an esthetic standpoint. The loss of mechanical properties was generally most pronounced during the initial period of contact between the mouthwashes and the tested material, which should be considered as unfavorable. The influence of ethanol molecules on mechanical properties was not stronger than that of many ethanol-free solutions. The frequently suggested correlation between changes in composite material hardness and the pH values of mouthwashes was not confirmed.