Physical Properties of Polyamide-12 versus PMMA Denture Base Material

Abstract

Objectives.Polyamide-12 (PA) is a flexible material suited for denture bases and clasping. This study investigated its potential aging effects with a focus on surface roughness, color stability, and elasticity.Methods.PA specimens (Valplast) of40×10×2 mm and equally measuring PMMA specimens (Palapress) as control were fabricated. Color changes after storage in air, water, coffee, and red wine(n=10)were measured using the CIEL*a*b*color specification. Elasticity after thermocycling (1000, 3000, and 7000 cycles,  n=15) was measured by three-point bending testing. Mean surface roughness (Ra) was determined after storage in the liquids mentioned above and thermocycling(n=10).Results.Tukey’s HSD test(P<0.05)revealed statistically significant color changes of PA in red wine (ΔE=4.27after 12 days,ΔE=6.90after 12 days) and coffee (ΔE=3.93after 36 days) but no color changes in PMMA. Elastic modulus of PA was 845 MPa and not affected by thermocycling (Tukey's HSD test,  P>0.81). Dry specimens showed significantly decreased elasticity(P<0.001). Mean surface roughness (PA 0.20 μm, PMMA 0.28 μm) did not change significantly after thermocycling or storage (Mann-WhitneyU-test,  0.16<P<0.65).Significance. PA exhibited a higher susceptibility to discoloration than PMMA. Neither surface roughness nor elasticity of PA was altered by artificial aging.