Functional alterations in pulpal microcirculation in response to various dental procedures and materials

Using the quantitative 15 microns microsphere injection method, the effects of several restorative procedures on pulpal microcirculation in dog canine teeth were investigated. Pulpal blood flow (PBF) decreased steadily as the remaining dentin thickness (RD) became smaller with crown preparation without water spray. One hour after the preparation wit 1/3 RD (approximately 1 mm) PBF was reduced to 10% of the control, indicating that dry deep preparation has a deleterious effect on PBF. A careful preparation to an RD of 1 mm under copious water spray had a negligible effect on PBF. Dry preparation to an RD of more than 50%, on the other hand, caused a significant increase in blood flow through shunt vessels, AVAs and "U"-turn loops as determined with the 9 microns and 15 microns microspheres. These shunt vessel activities were especially prominent in the apical portion of the pulp, suggesting that the activation of the shunt vessels may be one of the compensatory mechanisms of the pulp in response to inflammation. In rat incisor teeth observed by intravital microscope, shunt vessels opened up as the incisor tips were drilled. Impression procedures after tooth preparation with water spray using the copper band with wax caused severe flow fluctuation as compared to rubber base material impression. In anesthetics, the use of epinephrine was found to be the single most important factor affecting pulp circulation. Whether it is by infiltration or mandibular block, the use of epinephrine containing anesthetic caused a severe reduction in PBF.(ABSTRACT TRUNCATED AT 250 WORDS)