DECISIVE INFLUENCE OF ENAMEL SURFACE LAYER ON CORROSION RESISTANCE AND DEGRADATION OF HUMAN TEETH ENAMEL IN WHITE WINE

Objectives: To evaluate enamel degradation in white wine at simulated body temperatures (25, 37°C) and the influence of the acidic corrosive agent on the natural enamel surface as well as on the surface where the upper layer of natural enamel was removed by polishing. Methods: The content of major (Ca, P, Mg, K, Na), and minor (Al, Cu, Fe, Mn, Zn) components in the corrosion solution of white wine, and chemical composition of enamel were determined by atomic emission spectrometry in inductively coupled plasma (ICP AES). The chemical resistance of enamel in wine was monitored through determination of major components of enamel, i.e. calcium and phosphorus leached to the corrosion solution, combined with detailed study of corroded surfaces by SEM. The initial rates of corrosion per hour were calculated by linear curve fitting under quasi-dynamic conditions. Results: Time dependences of normalized leaching values of phosphorus and calcium nl(P) and nl(Ca) in the initial time period of the corrosion test are comparable, which refers to congruent dissolution of hydroxyapatite as the main component of natural teeth in the initial 3 hours period of the corrosion test. Demineralization of the enamel exposed to white wine at temperatures 25°C and 37°C in the initial time period is gradually reversed through re-mineralisation from calcium saturated corrosion solution. Removal of the approximately 1 mm thick surface layer of the enamel by polishing results in fivefold increase of the initial dissolution rates of enamel in white wine. Conclusions: Upper, approximately ~1 mm thick, enamel layer has a substantial influence on the chemical durability of human teeth in white wine solution.