Which of the following is NOT a factor influencing color stability during the polymerization of denture acrylic?

• A. Ambient lighting during curing
• B. Heat
• C. Time
• D. Residual monomer

Answer: (A)

Color stability in heat-cured denture base acrylic depends on how completely the polymerization occurs, which is influenced by heat, time, and the amount of residual monomer. Heat provides the energy to start and drive the polymerization, helping achieve a higher degree of conversion; longer curing time allows more complete reaction, reducing residual monomer that can cause color changes or staining. Residual monomer itself affects color stability because unreacted monomer can migrate or interact with pigments, leading to discoloration over time. Ambient lighting during curing, on the other hand, is not a factor because the polymerization of this denture resin is thermally activated, not light-activated, so the lighting conditions do not influence color stability.