The effect of processing methods and acrylic resins on the accuracy of maxillary dentures and toothless denture bases: an in vitro study.

ABSTRACT

OBJECTIVE: To compare the dimensional changes of two autopolymerising denture base resins using three different processing techniques. METHOD AND MATERIALS Sixty edentulous denture bases were made from the polymethylmethacrylates FuturaGen and PalaXpress. Ten bases were made from each resin using a manual injection technique (MI), a pneumatic injection technique (PI), and the fluid resin technique (F). Posterior palatal gap widths between casts and denture bases were measured. For an additional three-dimensional examination of occlusal changes, 10 maxillary dentures were made using FuturaGen/MI and 10 using PalaXpress/PI. Intermolar widths and changes in vertical dimension were determined. In all groups, measurements were taken after polymerization, after removal and repositioning, after polishing, and after storage in water for 1 and 3 weeks. Data were analyzed by using two-way ANOVA and Tukey test (P < .05). RESULTS: There were no differences in dimensional changes of FuturaGen and PalaXpress specimens. The pneumatic injection system produced significantly smaller posterior palatal gaps after storage in water for 3 weeks compared to the manual injection system (P < .0005) and the fluid resin technique (P = .003). The posterior gaps of dentures were ⋜ 0.04 mm and below the recommended depth for carving a posterior palatal seal (0.4 to 3.0 mm). CONCLUSION: The processing technique rather than the choice of the two resins seems to be the dominate variable with respect to dimensional changes.