Effect Of A Bondmaterial On The Rat Dental Pulp Microcirculation I. Iványi, Á.E. Balogh, L. Rosivall*, I. Nyárasdy (Semmelweis Medical University, Department Of Conservative Dentistry, *Department Of Pathophysiology, Budapest, Hungary) Chemically active resin composite materials directly placed on the conditioned dentin may adversely influence the microcirculation of the dental pulp.   In the present study, the technique of vitalmicroscopy (VM) and the technique of laser Doppler flowmetry (LD) were used to determine the acute circulatory effect of lege artis applied adhesive system (Scotchbond Multipurpose Adhesive System, 3M) on the living pulp of rat.   The first lower incisor of the anaesthetised male Sprague-Dawley rats (weighing 337 ± 15 g SE, n=40) was prepared for examination. The vascular diameter was assessed with VM (n=20), the pulpal blood flow with LD (n=20). Both groups were divided into two subgroups (control n=10, and examination group n=10). Changes in pulpal circulation were recorded prior to, and 1, 5, 15, 30 and 60 minutes after the bonding agents or saline (control) were administered on dentin.   In control rats both the vessel diameter and the blood flow was stable during the experiment. However, in the presence of bonding materials the vascular diameter was increased during experimental period (10.75 ± 3.03%; 12.15 ± 2.85%; 16.36 ± 2.39%; 14.16 ± 3.48%; 12.12 ± 3.72%; mean + SE; ANOVA, p≤0.05). There were a significant blood flow elevation in the 1st and the 15th min (51.61 ± 24.76%; 39.53 ± 14.79%).   These results suggest that composite resin bonding agents applied onto a thin layer of dentin have acute vasodilating and consequently blood flow increasing effect in the dental pulp, however do not provoke irreversible changes. The consequence of this vascular alteration in the dental pulp remains to be elucidated. These results indicate, that vitalmicroscopy and laser Doppler flowmetry seems to be a valuable aid to determine the biocompatibility of dental materials.   This study was supported by the grant: OTKA T023937, ETT T-13 453/96.