Effectiveness of CPP-ACP and fluoridated toothpastes in preserving enamel microhardness after erosion and abrasion challenges at different time intervals

Objectives: To investigate the impact of fluoridated (1450 ppm F⁻) and CPP-ACP (MI Paste) toothpastes applied after different time points following erosive-abrasive challenge on the perseverance of enamel hardness. Materials and Methods: Enamel specimens were subjected to an erosive-abrasive model using erosive beverage and toothbrushing simulation. The erosive challenge was achieved by soaking the specimens in Coca-Cola for 2 min. Distilled water was used as a control. Then, the specimens were subjected to brushing using fluoridated and CPP-ACP dentifrices applied via a brushing simulation device. The waiting time between the erosive and abrasive challenges was investigated at four levels (0, 15, 30, 60 min). The Vickers’ microhardness values of enamel at baseline and after the erosive-abrasive challenge were analyzed. Paired t-test and ANOVA analyzed the data. Results: Following brushing with distilled water and fluoridated toothpaste, a significant reduction in enamel microhardness was observed at all time points (before vs. after) (P < 0.01). Brushing with CPP-ACP toothpaste achieved significant enamel microhardness reduction at 0 min (P < 0.001) and 30 min (P = 0.007). The erosive challenge and the toothpaste type were significant factors (P < 0.001) in modulating the enamel microhardness but not the waiting time (P = 0.149). There were significant interactions between the erosive challenge and the waiting time (P = 0.005), the toothpaste time and the waiting time (P < 0.001), and there was a significant interaction between the three variables (P = 0.005). CPP-ACP and fluoridated toothpastes resulted in less microhardness reduction compared to brushing using distilled water (P < 0.05), with no difference between CPP-ACP and fluoridated toothpastes. Conclusion: This study found that both fluoridated and CPP-ACP toothpastes are equally effective in protecting enamel, and delaying toothbrushing offers no protective benefits after such exposure. Delaying toothbrushing did not provide any protective benefits for enamel following exposure to the erosive-abrasive model, as fluoridated and CPP-ACP toothpastes were effective in protecting the enamel hardness.