Comparison of residual monomer release from denture bases manufactured with different techniques

Background. Residual monomer release from resin-based materials may vary depending on the production method. Since monomer release can affect material performance and biocompatibility, it is important to understand these differences. This in vitro study aimed to compare the impact of different production methods on residual monomer release and its time-dependent changes in artificial saliva. Material and methods . A total of 40 disk-shaped specimens (Ø10×3 mm])were prepared using 4 different production techniques: conventional heat polymerization (CH), injection molding (IM), CAD-CAM milling (CM), and 3D printing (3D) (n = 10). The specimens were stored in 1 mL of artificial saliva solution (pH: 6.8) in separate glass tubes at 37°C in an incubator. To mimic the oral environment, the artificial saliva solution was changed daily. To determine the amount of monomer released at different times, artificial saliva samples were extracted on days 1, 2, 3, 7, and 15. Residual monomer amounts were analyzed using high-performance liquid chromatography (HPLC). The obtained data were analyzed using the Kruskal-Wallis H and 1-way analysis of variance (ANOVA)tests. Results. All groups exhibited the highest level of residual monomer release within the first 24 hours, followed by a progressive decrease over time. When the cumulative 15-day values were evaluated, Groups IM and 3D demonstrated lower overall monomer release compared with Groups CH and CM. Conclusions. In all groups, residual monomer release was highest in the first 24 hours and decreased over time, revealing that the production technique has a determining effect on the amount of residual monomer.