Protective effect of fluoride dentifrices in association with aminomethacrylate polymer against the enamel erosive wear

Abstract

The erosive tooth wear (ETW) has been a cause of concern, because its prevalence rates have increased in the recent years, mainly in young individuals. Film-forming polymers have been investigated as an alternative to control erosive tooth wear (ETW) progression, notably when associated to fluoride compounds, protecting the dental tissues against acids. Among them, the aminomethacrylate polymer has shown promissing results in previous studies. Nevertheless, its performance when added to toothpaste formulations remains unknown. Therefore, this study aims to evaluate the protective potential of fluoride toothpastes associated with aminomethacrylate against the initial erosion and erosive wear in enamel. For this, 60 polished bovine enamel specimens (4mm diameter) will be divided in six treatments: ultra-pure water (erosion negative control without abrasive challenge- ENC), ultra-pure water (abrasion negative control abrasion without toothpaste- ANC), toothpaste without active agent (placebo- PL), toothpaste with sodium fluoride (NaF- 1450 ppm F-), experimental toothpaste with amonomethacrylate (AMC- 2%), and experimental toothpaste with sodium fluoride + aminomethacrylate (NaF+AMC). The NC group will be subjected to erosion only. The other groups will be subjected to erosion + abrasion. Two response variables will be analyzed: initial erosion with Knoop surface microhardness (KN) in the first day of the cycle, and enamel loss with profilometric analysis (¼m) at the end of the cycle. The erosive/abrasive cycling will consist of immersion of the specimens in human saliva (1 h) to form the acquired pellicle, exposure to citric acid (0.3%) for 5 minutes (4x/day) and treatments application under abrasion (2x/day), with immersion in saliva in the intermediate periods (1 h). This cycling will be repeated for 5 days. The microhardness will only be assessed in the first cycle, in four moments: KNinitial (sound enamel), KNE1 (after the first acid exposure), KNT (after the treatment), KNE2 (after the second acid exposure). The profilometric analysis will be performed before the first cycle and after the last cycle. Then, the difference between the initial and final profiles will be calculated to obtain the enamel loss. Representative specimens from each group will be analyzed by scanning electron microscopy (SEM). The data will be analyzed considering the normality and homoscedasticity to the application of an appropriate statistical test. The level of significance will be 5%.