Microstructural Evaluation of Bovine Enamel Exposed to Fermented Dairy Beverages and Analysis of their Physical-Chemical Properties

Abstract

Objective: The aim of this study was to analyze the pattern of demineralization of bovine enamel subjected to the action of fermented dairy beverages after different times and to evaluate their physical-chemical properties. Method: Six brands of dairy beverages were analyzed, having cola-type soft drink and distilled water as positive (PC) and negative (NC) controls, respectively. The pH was evaluated using a digital pH-meter and the soluble solids content (°Brix) was measured using a specific field refractometer. A capillary viscometer measured the kinematic viscosity. The action of the beverages on enamel was analyzed by scanning electron microscopy (SEM) after exposure to solutions at the following time intervals: 5, 15 and 30 minutes. The microstructural alterations were scored according to the degree of demineralization observed on tooth structure. Results: The pH values ranged from 2.59 (PC) to 6.24 (NC), while the pH of the fermented dairy beverages was below 3.92. The soluble solids content values ranged from 0° to 19° Brix and viscosity ranged from 2.41 to 7.26 mm²/s. Changes suggestive of erosion were evident in the specimens submitted to the PC and to the beverage with the lowest pH. Most beverages promoted initial enamel dissolution after 15 minutes, corresponding to grade 1 alterations (mild microstructural alteration). Conclusion: The fermented dairy beverages were found to be potentially erosive and cariogenic, presenting pH values compatible with the critical value for enamel dissolution as well as total soluble solids and significant viscosity variation. Morphological analysis of tooth surface by SEM revealed microstructural changes from mild to severe, according to the exposure time to the beverages