Effects of nonaldehyde immersion disinfection on the mechanical properties of flexible denture materials

Variation in the baseline mechanical properties of polyamide thermoplastic polymers used in the fabrication of prosthetic dental appliances and the effects of nonaldehyde disinfectants on the mechanical properties of these polymers are unclear.

The purpose of this in vitro study was to compare the flexural and impact strengths of 2 flexible denture materials (Valplast and Sunflex) and evaluate the effect of 24-hour immersion in nonaldehyde disinfectant (Perform) on their flexural and impact strengths.

Of 48 specimens of Valplast and Sunflex, half were immersed in nonaldehyde disinfectant solution containing the active ingredient 2% peroxymonosulfate for 24 hours. Flexural and impact strengths were measured using a universal testing machine. The Student t test with Bonferroni correction was used (α=.008).

For the Valplast group, the mean ±standard deviation flexural strength was 27.8 ±0.57 MPa, and the impact strength was 3.5 ±0.98 kJ/m². For the Sunflex group, the mean flexural strength was 57.4 ±4.09 MPa, and the impact strength was 6.0 ±3.11 kJ/m². Sunflex showed greater flexural strength (P≤.001) and impact strength (P=.001) than Valplast. A significant increase in the impact strength (P≤.001) but not in the flexural strength of Valplast was observed after exposure to the disinfectant solution. Immersion disinfection had no significant effect on the strength of Sunflex.

The flexural and impact strengths of Sunflex were significantly greater than those of Valplast. Immersion disinfection with peroxymonosulfate had no significant effect on Sunflex but increased the impact strength of Valplast.