Previous in vitro studies assessing the tubule occluding properties of various desensitizing agents in the dentine disc model appear to provide only qualitative data. The aim of this study was to establish a reliable and reproducible system to evaluate the in vitro effectiveness of three desensitizing agents. Six selected fields from SEM negatives (magnification x1000; working distance 10mm) of test and control dentine disc specimens treated with the desensitizing agents (Butler Protect, Colgate FluoriGard (GelKam), Macleans Sensitive) were evaluated. Fields were assessed using a Quantimet 520 Image analysis system (Leica UK) and the data recorded included patent tubule area, mean tubule diameter, mean patent/field area and number of tubules per unit area. Comparison of test and control specimens indicated that differences in the number of tubules, patent area, width of tubules and percentage of patent areas can be assessed quantitatively Furthermore, this methodology also demonstrated differences between the tubule occluding properties of the selected desensitizing agents
