Effects of CPP-ACP and Remin-Pro on Surface Roughness of Bleached Enamel: an Atomic Force Microscopy Study

Objectives Bleaching agents can change the organic and mineral contents of the tooth structure. The aim of this study was to evaluate the effects of two remineralizing agents on surface roughness of bleached enamel. Methods In this experimental study, 24 premolars were collected. The testing area was a window measuring 3 × 4 mm. First the surface roughness of specimens was measured by atomic force microscopy (AFM). Then, the teeth were bleached. Surface roughness was measured again. Specimens were randomly divided into 3 groups. No remineralizing agent was applied in the control group (A). Casein phosphopeptide amorphous calcium phosphate (CPP-ACP) and Remin-Pro were used in groups B and C, respectively. After 15 days, the surface roughness was measured. The changes in surface roughness were analyzed by paired t-test, and comparison between the groups was done by the Welch and Games-Howell post hoc tests. Results The surface roughness increased after bleaching (P<0.000). Surface roughness in groups B (P=0.03) and C (P=0.04) was significantly lower than that in group A. There was no significant difference in the level of surface roughness reduction between groups B and C. The Welch test revealed that the mean change in surface roughness values after remineralization in groups B and C was significantly higher than that in group A (P=0.001 and P=0.002, respectively). The difference between groups B and C was not significant (P=0.97). Conclusion CPP-ACP and Remin-Pro reduce the surface roughness of bleached enamel more effectively than the saliva

Comparative Effects of Three Bleaching Techniques on Tooth Discoloration Caused by Tea

Objectives: This study aimed to investigate the impact of three different bleaching protocols on tooth discoloration caused by tea. Materials and Methods: Forty extracted sound premolars were cleaned, disinfected, and their initial color parameters were measured (T1). The teeth were then immersed in boiled tea solution for 24 hours, and their color was measured again (T2). The samples were divided into four groups of 10 teeth each. Group A was treated with an in-office bleaching gel followed by 30 seconds of light curing. Groups B, C, and D were respectively treated with 0.24M oxalic acid followed by bleaching gel, 5.25% sodium hypochlorite followed by bleaching gel, and a combination of 0.24M oxalic acid, 5.25% sodium hypochlorite, and bleaching gel. The color was measured once more after the interventions (T3). Data were analyzed using two-way repeated measures ANOVA, paired sample t-test, and Tukey's test. Results: The mean color change (∆E2) between T2 and T3 was significantly higher in group D compared to group A (P<0.05). However, there was no significant difference in color change between groups A, B, and C. Additionally, there was no significant difference in color change between groups B, C, and D. The groups also showed significant differences in ∆L (P=0.007), with the only significant difference found between groups B and C (P=0.001). Conclusion: The combined use of sodium hypochlorite and oxalic acid followed by in-office bleaching gel is more effective than bleaching alone in correcting tooth discoloration caused by tea. This protocol can further reduce yellow coloration

Phosphate Ion Release and Alkalizing Potential of Three Bioactive Dental Materials in Comparison with Composite Resin

Aim. Several new bioactive compounds were recently introduced to the market with favorable ion release, tooth remineralization, and alkalizing potential. This study sought to compare the phosphate ion release and alkalizing potential of three bioactive materials in comparison with composite resin. Methods. Thirty-six discs (2 × 6 mm) were fabricated from Fuji II LC resin modified glass ionomer (RMGI), Activa BioActive, Cention N, and Z250 composite in plastic molds. The specimens were stored in distilled water for 24 and 48 h and 6 months. Half of the specimens were used to assess the phosphate ion release while the other half were used to assess the alkalizing potential 1 h after pH drop from 6.8 to 4. Phosphate ion release was quantified by a spectrophotometer while the pH value was measured by a pH meter. Data were analyzed using two-way ANOVA, one-way ANOVA, and Tukey’s HSD test (for pairwise comparisons) at 0.05 level of significance. Results. At 24 h, the maximum phosphate ion release in distilled water occurred in the Fuji II LC group followed by Cention N, Activa BioActive, and Z250. At 6 months, Cention N followed by Activa BioActive showed higher phosphate ion release than Fuji II LC and Z250. No significant difference was noted between Activa BioActive and Cention N at any time point. All materials, except for Z250, increased the pH of the environment. Fuji II LC had maximum alkalizing effect at all time points followed by Cention N and Activa BioActive. Conclusion. Use of bioactive compounds is a promising method to ensure phosphate ion release, and can have a positive effect on tooth remineralization over time. Also, bioactive compounds can alkalize an acidic environment