Development of toothpaste formulations containing mineral clays as abrasive agents and their effects on the physical properties of dental enamel

Abstract

To assess the physical properties and topographical aspect of dental enamel's surface microhardness (KHN), surface roughness (Ra), and color parameters CIELAB (∆E_ab*), CIEDE 2000 (∆E₀₀), and whiteness index for dentistry (∆WI_D) after toothbrushing with experimental toothpaste formulations with the following mineral clay types: kaolin, Sparclay SGY, and Tersil CGY used as abrasive component. Scanning electron microscopy (SEM) was performed for topographical analyses purposes. A total of 96 bovine incisors were used in the experiment. They were divided into eight experimental groups (n = 12), namely: NC—negative control (no treatment), CT12—Colgate Total 12®, CMP—Colgate® Máxima Proteção Anticáries, K—kaolin experimental toothpaste, SGY—Sparclay SGY experimental toothpaste; CGY—Tersil CGY experimental toothpaste, SD—SiO₂ experimental toothpaste, and CC—CaCO₃ experimental toothpaste. All samples were subjected to mechanical brushing protocol with 5000 cycles and kept in artificial saliva with daily exchanges. KHN was analyzed through the mixed linear model for repeated measures over time. Ra was analyzed through nonparametric Kruskal Wallis and Dunn tests to compare the groups. Paired Wilcoxon test was run to compare experimental times. ∆WI_D, ∆E_ab*, and ∆E₀₀ were analyzed through Kruskal Wallis and Dunn tests. All analyses were performed in R* software, at 5% significance level. EXP_SGY recorded higher KHN than EXP_SiO₂ and EXP_CaCO₃, whereas EXP_K showed increased Ra in comparison to CMP (p = 0.0229). ∆E_ab and ∆E₀₀ were significantly higher in the CT12, EXP_SiO₂, and EXP_CaCO₃ groups than in the NC and EXP_K (p < 0.0001). There were no significant changes in ∆WI_D (p = 0.0852). According to SEM results, toothbrushing with experimental toothpastes added with mineral clay types did not have significant impact on enamel's polishing and smoothness.

Clinical Relevance

Mineral clays have a broad application in the cosmetic industry, and recently, they have been used in the formulation of vegan toothpaste.