Bovine dental enamel brushing with charcoal-based dentifrices: chemical, mechanical and morphological analyses

Abstract

Dental abrasion is characterized by physical wear caused by materials other than the tooth. It is a type of loss of the dental surface caused by sliding or rubbing of abrasive external objects against the tooth surface. There is a loss of dental structure due to the mechanical forces of a traumatic brushing, potentially abrasive toothpaste or the action of hard bristles on toothbrushes, among other causes. The activated charcoal was incorporated into the toothpaste, being justified as an element that contains properties such as the adsorption of molecules on its surface and porosity. The commercialization of these toothpastes is free and their use has been popularized as home tooth whitening; however, few studies have proven its effectiveness and safety. In this sense, the present project aims to analyze the dental abrasion, evaluating the effects of the abrasiveness of dentifrices with activated charcoal on the composition, texture and surface morphology of the bovine dental enamel submitted to brushing. This project also proposes the use of the µ-EDXRF technique as an alternative methodology for indirect assessment of wear on the dental surface. 25 samples of bovine teeth will be used, cut in order to obtain a total of 50 samples. After sample preparation, a semiquantitative analysis will be performed by dispersive energy x-ray microfluorescence (µ-EDXRF) (1st reading, 50 mappings) in order to quantify the calcium (Ca) and phosphorus (P) of the prepared samples and thus be able to perform the separation of samples in homogeneous experimental groups. The samples will be divided into five groups: G1 - Oral-B complete® (negative control), G2 - Colgate Luminous White Expert® (positive control), G3 - Curaprox Black Is White® (activated charcoal), G4 - Colgate Natural Extracts Purifying ® (activated charcoal), G5 - Oral-B 3D White Mineral Clean® (activated charcoal). A first roughness measurement will be performed on all samples (1st reading, 150 readings) to be used later in statistical comparisons with data after brushing. The simulated brushing process will be carried out using a Brush Simulation Equipment (speed of 4.5 cycles per second, load of 200 grams force). A simulated brushing will be performed with a total of 2500 reciprocal movements, representing a period of approximately two months of brushing. The samples will be brushed with a soft brush and specific toothpaste. Each toothpaste will be diluted in artificial saliva (in a 1: 3 ratio). After brushing, new measurements will be made on the roughness tester (2nd reading, 150 readings) and in-line mapping by µ-EDXRF (2nd reading, 50 mapping). Area mappings by µ-EDXRF of a representative sample from each group will also be carried out (2nd reading, 5 mappings). The semiquantitative (µ-EDXRF) and quantitative (Ra) data will be analyzed statistically with the aid of the GraphPad Prism program. The statistical analysis of the data obtained will be performed by Dunnett's multiple comparison test (negative / positive control comparison and treatments) and by Bonferroni's multiple comparison test (treatment comparison). Enamel analysis by scanning electron microscopy (SEM) will evaluate the surface morphology of two representative samples from each group after treatments (N = 10). In each sample the micrographs will be obtained in three increments (1,000, 5,000 and 10,000x, 30 images). With the data obtained, it is intended to determine the abrasive potential of the tested toothpastes and to indicate a product that changes the dental structure to a lesser extent. For a correct indication and use to be made, dental professionals must have knowledge of the mechanism of action and function of these toothpastes in order to reduce negative impacts on indiscriminate use by the patient. (AU)