[Effect of conditioning on the circulation of rat teeth].

Materials employed in "adhesive filling technique" often lack informative instructions concerning the depth of cavities which require lining. Etching-materials directly placed on the dentin can adversely influence the pulp leading to changes in local microcirculation which can be an early sign of the pathological changes in the pulp. Therefore, it is worth examining the effect of these materials on the diameters of pulpal vessels. In the present study we examined wether acid etching (test1: 15 s and test2: 60 s) alters the blood circulation of the pulp lower incisors, by applying it directly onto a thin layer of pulpal wall (40-50 microns) without any liner, and following the instructions provided by the manufacturer. Twenty male Sprague-Dawley rats (weighing 330 +/- 51 g) and the technique of vitalmicroscopy was used for this investigation. The left lower incisors of the rats were prepared for vitalmicroscopy. Changes in vessel diameter were recorded prior to and 5, 15, 30 and 60 minutes after investigated materials or saline (control) were administered on dentin. In control and test1 group the vessel diameter was unchanged during the experiment. However, in group test2 an intense vasoconstriction was registered. There were significant (p > 0.05, ANOVA) differences in diameter changes between the control group and those treated with acid etching for 60s. Our results suggest that extended etching time may affect the circulatory system in the dental pulp, when applied onto very thin layer of dentin.