Evaluation of the Effect of Brushing on Vickers Microhardness of Acrylic Denture Base Resins Polymerized by Different Techniques

Objectives: To prevent the negative effects of brushing on the microhardness of the acrylic resin, different polymerization techniques may be taken into consideration while choosing the denture base material. This study's objective was to assess how brushing affected the Vickers microhardness of acrylic denture base resins polymerized using various methods. Materials and Methods: From each acrylic resin (Integra and FuturaJet), 100 disk-shaped specimens (15 mm in diameter and 2 mm thick) were created. A total of five distinct polymerization processes—the traditional water-bath method, short and long autoclave polymerization, injection-molding polymerization, and auto-polymerization—were examined (n=20). An automatic brushing machine was used to imitate brushing on half of the specimens, applying 54 000 brush strokes each specimen. All specimens were then subjected to a Vickers hardness test with a 300-g force for 15 s. Data analysis was done using the Mann-Whitney U test, Kruskal-Wallis test, and Dunn's post-hoc test; statistical significance was set at p<0.05. Results: In all polymerization methods, a statistically significant difference was seen between the control and brushing groups. The autopolymerized acrylic resin group substantially had lower microhardness values than the control and brushing groups' short, long autoclave, and water bath-polymerized resins. Conclusions: The microhardness of acrylic denture base resins should be taken into consideration when considering polymerization procedures because the autopolymerization method may have certain drawbacks in terms of preventing negative effects of brushing on the microhardness.