A simple, sensitive and non-destructive technique for characterizing bovine dental enamel erosion: attenuated total reflection Fourier transform infrared spectroscopy

Although many techniques are available to assess enamel erosion in vitro, a simple, non-destructive method with sufficient sensitivity for quantifying dental erosion is required. This study characterized the bovine dental enamel erosion induced by various acidic beverages in vitro using attenuated total reflection Fourier transform infrared (ATR-FTIR) spectroscopy. Deionized water (control) and 10 acidic beverages were selected to study erosion, and the pH and neutralizable acidity were measured. Bovine anterior teeth (110) were polished with up to 1 200-grit silicon carbide paper to produce flat enamel surfaces, which were then immersed in 20 mL of the beverages for 30 min at 37 °C. The degree of erosion was evaluated using ATR-FTIR spectroscopy and Vickers’ microhardness measurements. The spectra obtained were interpreted in two ways that focused on the ν1, ν3 phosphate contour: the ratio of the height amplitude of ν3 PO4 to that of ν1 PO4 (Method 1) and the shift of the ν3 PO4 peak to a higher wavenumber (Method 2). The percentage changes in microhardness after the erosion treatments were primarily affected by the pH of the immersion media. Regression analyses revealed highly significant correlations between the surface hardness change and the degree of erosion, as detected by ATR-FTIR spectroscopy (P<0.001). Method 1 was the most sensitive to these changes, followed by surface hardness change measurements and Method 2. This study suggests that ATR-FTIR spectroscopy is potentially advantageous over the microhardness test as a simple, non-destructive, sensitive technique for the quantification of enamel erosion. A sensitive spectroscopy technique could provide a simple, non-invasive way of measuring the extent of dental enamel erosion. Tooth enamel is prone to softening and erosion caused by consuming acidic foods and drinks, and a highly sensitive and non-destructive way of measuring the resulting damage is needed. Tae-Yub Kwon at Kyungpook National University and co-workers across South Korea compared an existing enamel microhardness test (Vickers) with a technique called attenuated total reflection Fourier transform infrared spectroscopy, or ATR-FTIR, capable of revealing microscopic changes on a molecular level. The team immersed cattle teeth in ten different acidic drinks, and interpreted the resulting ATR-FTIR spectra. Their method proved more sensitive than the Vickers test, giving detailed insights into surface hardness and erosion. Crucially, using ATR-FTIR would allow scientists to monitor enamel changes repeatedly in the same teeth over time.