Objective: Evaluate the effect of acidic, neutral and alkaline food colorant medium (FCM) on tooth discoloration in-vitro. It was hypothesized acidic FCM would cause more discoloration (extrinsic and intrinsic) than neutral or alkaline FCM. Methods: Treatment (T, n=24) and control (C, n=24) sterile, hydrated human molars were prepared in individual, impervious holders and their color measured (Pre-test) using a non-contact spectroradiometer system. Specimens were randomly assigned to and immersed in one of 3 buffer solutions (pH2, pH7 or pH12). Red food color (Red40) was added to the T buffer solutions at 0.025%. Immersed samples were incubated for four hours at 37şC. Colors were also measured after immersion/incubation (Post-test) and again after subsequent two-minutes of polish using a plain-pumice slurry with a slow-speed handpiece (Post-polish). Differences in CIE a* (redness parameter) were analyzed by Repeated Measures ANOVA with Bonferroni-corrected t-tests for the pairwise comparisons of interest. Results: Mean Δa*(±SD) posttest to pretest Group | pH2(n=8) | pH7(n=8) | pH12(n=8) | Control | 0.322 (±0.374)a | -0.158(±0.215) | -0.136(±0.185) | Treatment | 5.490(±4.632) a,b,c | 0.455(±0.325)b | 0.088(±0.188)c | ap<0.001,bp<0.001,cp<0.001 Mean Δa*(±SD) post-polish to pretest Group | pH2(n=8) | pH7(n=8) | pH12(n=8) | Control | -0.261(±0.346)a | -0.033(±0.125) | -0.224(±0.90) | Treatment | 2.393(±2.737) a,b,c | 0.241(±0.192)b | -0.039(±0.163)c | ap<0.001,bp<0.003,cp<0.001 Mean Δa*(±SD) post-polish to posttest Group | pH2(n=8) | pH7(n=8) | pH12(n=8) | Control | -0.583(±0.398)a | 0.125(±0.241) | -0.088(±0.201) | Treatment | -3.097(±2.539) a,b,c | -0.214(±0.286)b | -0.127(±0.150)c | ap<0.001,bp<0.001,cp<0.001 Conclusions: A significant change in color was not observed between C and T for neutral and alkaline FCM. However, acidic FCM caused tooth discoloration posttest to pretest, post-polish to pretest and post-polish to posttest compared to C and T (neutral and alkaline). Discoloration in acidic FCM represented both extrinsic (mean difference between post-polish and posttest) and intrinsic (mean difference between post-polish and pretest) stain. Although food/beverage-pigments are associated with extrinsic stain, these preliminary results suggest that degree and type of stain are influenced by pH. |