Surface area and pore size analysis for human enamel and dentine by water vapour sorption

The water sorption apparatus described allowed water sorption isotherms to be plotted on several samples simultaneously, with the added possibility of recording their nuclear magnetic resonance spectra for any points on the isotherm. Water sorption showed that human dentine had a saturated water content (removable in vacuo at room temperature) of approx. 10 per cent w/w (21 per cent v/v), probably in micropores or associated with the organic phase, and a specific surface of approx. 150 m2/g. A similarly measured water content for outer enamel was approx. 0.9 per cent w/w (2.7 per cent v/v), with a specific surface of 5.5 m2/g. For whole enamel, the slightly larger values of 1.15 per cent w/w (3.4 per cent v/v) and 8.7 m2/g were obtained. Results are shown to depend upon the conditions of measurement. Pore-size distribution analysis of enamel and dentine by water sorption, in this study and in investigations by others, is shown to be subject to many uncertainties and of doubtful value. Some uncertainty is also believed to apply to surface area measurements.