The residual monomer content and mechanical properties of CAD\CAM resins used in the fabrication of complete dentures as compared to heat cured resins

BACKGROUND: The utilization of computer-assisted designing and computer-assisted milling CAD\CAM resins in the fabrication of removable prostheses is a modern-day concept that offers many advantages over the use of the traditional polymethylmethacrylate (PMMA). AIM: This study instigated some of the mechanical properties of CAD\CAM denture base resin including the amount of residual monomer. METHODS: This study was conducted at the Faculty of Dentistry, King Abdulaziz University from October 2016 to February 2017. A total of seventy rectangular specimens were fabricated (group A: 35 heat-cured PMMA and group B: 35 CAD/CAM pre-polymerized acrylic resin blocks). The flexural strength and surface hardness were tested while the residual monomer content at baseline, two-day and seven-day intervals was estimated using gas chromatography (GC). Means and standard deviations were determined for each group as well as independent-samples t-test and ANOVA with repeated measures for comparison between the groups and subgroups of varying time intervals. RESULTS: Heat cured PMMA (A), displayed higher flexural strength and low value flexural modulus compared to CAD/CAM acrylic resin denture base material (B). Student t-test indicated highly significant differences (p<0.001) of the flexural strength (t=37.911) and flexural modulus (t=88.559). The surface hardness of group (B) was significantly higher compared to group (A) as indicated by the t-test (t=20.430). Higher release of the monomer content was detected by GC in group (A) at different time intervals with a statistically significant difference (p<0.001) in residual monomer content. CONCLUSION: CAD/CAM resin may be considered suitable for use in the construction of denture bases.