Evaluation of Different Dentifrice Compositions for Increasing the Hardness of Demineralized Enamel: An in Vitro Study

This study aimed to evaluate microhardness of a dentifrice containing fluoride and arginine compared to a positive control (fluoride only) and a negative control (no fluoride) on sound and demineralized bovine enamel surfaces. Specimens were randomly assigned to different treatments that included daily pH cycling and brushing three times a day with one of the following dentifrices (n = 8): Neutraçucar (arginine and fluoride), Colgate Total 12 (fluoride) and My First Colgate (no fluoride). Enamel carious lesions were artificially created one week before the beginning of these treatments (demineralized bovine enamel (DE) groups). The same groups were also tested in sound enamel (sound bovine enamel (SE) groups). Microhardness was measured at baseline and after one, two, and five weeks of treatment using a Knoop indenter. Statistical analysis involved two-way Analysis of Variance (ANOVA) and Tukey’s test. After five weeks, both Total 12 and Neutraçucar had increased the microhardness of DE specimens (p < 0.05). Only Neutraçucar had increased the microhardness of the sound enamel after five weeks of treatment. Thus, it could be concluded that arginine-based dentifrices increase the microhardness of sound and demineralized bovine enamel surfaces.

Microhardness of bovine enamel after different fluoride application protocols

The aim of the present study was to evaluate microhardness, mineral recovery and the enamel surface after the application of topical fluoride to artificial dental caries. Twenty-five bovine enamel blocks were prepared for artificial caries-like lesions and randomly divided into five groups (n=5): untreated (C control), 1.23% acidulated phosphate fluoride gel (APG), 2% neutral fluoride gel (NFG), 1.23% acidulated fluoride mousse (AFM) and fluoride varnish (5% Duraphat, DFV). Knoop microhardness (KHN) was evaluated after 7 and 14 days of treatment as well as 1 week after 28 days of treatment. Electron and confocal microscopy and energy dispersive spectroscopy were performed. KHN data were treated with two-way ANOVA (material×time) and Tukey's test at a 5% significance level. Differences were found among groups over time (p<0.001). Microhardness varied after 7 and 14 days of treatment and remained stable 1 week after 28 days of treatment. Mineral recovery and enamel topography varied among groups, with the fluoride varnish achieving the most uniform topography.