Effect of mouthwashes on the microhardness of aesthetic composite restorative materials

Background. Mouthwashes are increasingly being used worldwide. However, these preparations are known to have a negative impact on composite resin dental restorations. In this study, we aim to evaluate the effect of mouthwashes on the microhardness of such restorations.Methods. Thirty specimens of Tetric N-Ceram composite were prepared. Each composite specimen was cured for 40 seconds and kept in saline solution for 24 hours at 37 & DEG;C. Baseline microhardness of each specimen was recorded using an Innovatest Vickers Micro Hardness Tester. Composite specimens were randomly placed in 20 mL of the selected mouthwashes (Colgate & REG; Plax, Listerine & REG; Teeth & Gum Defence, and Closeup & REG; Antibacterial Mouthwash Cool Breeze) and stored in an incubator for 24 hours at 37 & DEG;C. Next, microhardness values were rechecked. pH measurements were recorded for each type of mouthwash using a digital pH meter.Results. Due to the acidic nature of Colgate & REG; and Listerine & REG;, the microhardness of the restorations decreased with these mouthwashes; Listerine & REG; caused the greatest decrease in microhardness and had the lowest pH reading (4.34). For Closeup & REG;, with a neutral pH (7.02), no negative effect on microhardness was found; on the contrary, due to the presence of zinc in this latter mouthwash, an increase of the microhardness was found. Conclusions. We confirm the negative effect of acidic mouthwashes on the microhardness of composite dental restorations.