Effect of 0.2% Chlorhexidine and Alcohol-Free Listerine on Microhardness of Major Plus Acrylic Denture Teeth

Background and Aim: The hardness and wear resistance of denture teeth have great importance in the longevity of dentures. This study assessed the effect of 0.2% chlorhexidine (CHX) and alcohol-free Listerine on the microhardness of acrylic denture teeth. Materials and Methods: In this in-vitro experimental study, 26 Major Plus teeth were randomly divided into three groups for immersion in 0.2% CHX, alcohol-free Listerine, and distilled water. Two teeth were not immersed in mouthwash to assess baseline microhardness. The teeth were mounted in wax blocks (20×20×6 mm), which underwent wax burnout and were replaced with heat-cure acrylic resin. The samples were immersed in the solutions for 120 minutes corresponding to 4 months of clinical service. They were removed from the solutions twice daily, each time for 30 seconds, rinsed with distilled water, and placed again in the solutions. Next, they were stored at room temperature for 24 hours. They were thermocycled and subjected to microhardness measurement at the incisal third of their labial surface using the Vickers test. Data were analyzed using t-test. Results: The baseline microhardness (n=2) was 27.9±0.98. The microhardness of samples immersed in CHX was 12 units (36.8%) lower than that of samples immersed in distilled water; this difference was statistically significant (P<0.002). The microhardness of samples in Listerine was 7.4 units (29.4%) lower than that of samples in distilled water with no statistically significant difference (P=0.1). Conclusion: Immersion of acrylic teeth in 0.2% CHX can significantly decrease their microhardness. The effect of non-alcoholic Listerine on microhardness is similar to that of distilled water.