The acid etching process is the primary stage for preparation of dental composite restorations. Dentin specimens from extracted teeth are usually prepared by fracturing etched pieces of dentin. Etching creates a demineralized layer on the dentin surface with the thickness of a few microns. The layer consists of wet collagen and dissolved proteins; its drying process is of special interest in dentistry since it affects the bonding of the resin adhesives to dentin. Observations of fractured surfaces can be performed in either a conventional or an environmental SEM.

Three wet dentin samples were observed (XL30 FEG ESEM, FEI/Philips) in wet mode at 5°C Peltier cooling stage temperature and 5.8 MPa water vapor pressure. Samples with excess water on their top surface were put in an ESEM. Thickness measurements of the demineralized zone were begun immediately after the evaporation of this water layer with subsequent measurements taken after 5, 10, 20, 40, 60 and 100 minutes of drying.