Two different in-vitro simulation protocols to evaluate the color stability of heat cure acrylic resin denture base

Introduction In-vitro studies are required to predict the outcomes of in-vivo studies. Reliability of simulation protocols used in in-vitro test is an indication for its creditability. Up to our knowledge, no in-vitro method is yet available based on which resin material discoloration can be assessed with a high degree of sensitivity and specificity. Likely, there will never be a single laboratory test or a collection of tests that will accurately predict the clinical performance on specific materials. This, however, should not be an excuse for not improving and validating the laboratory test methods. Purpose To evaluate the effect of two different simulation protocol using the same discoloring agents and effect of brushing on color stability of heat cure acrylic resin denture base. Materials and Methods One hundred twenty heat cure acrylic resin disk samples, all were exposed to coffee, roselle, and cigarette smoke for a simulation period representing three months: half of samples were immersed in simulation mediums continuously without artificial saliva. Group A, the other half was exposed to simulation mediums and artificial saliva in a term of cycle repeated daily. Group B, each half was subdivided into two subgroups, one subgroup was brushed with soft toothbrush under water (A2, B2) while the other subgroup was rinsed with water (A1, B1). Color measurement was conducted by portable spectrophotometer. Results Statistically significant difference between the four subgroups, the highest color change was reported for subgroup (A1) followed by subgroups (A2, B1, B2) in order. Conclusion Simulation protocol in term of a cycle repeated daily is more representative to the oral cavity than continuous protocol, patients must be instructed to perform hygienic procedures daily to maintain the denture esthetics.