PULP INTERSTITIAL FLUID PRESSURE AND BLOOD-FLOW AFTER DENERVATION ANDELECTRICAL TOOTH STIMULATION IN THE FERRET

The effects of sensory and sympathetic denervation on simultaneously m easured interstitial fluid pressure and blood flow in the canine pulp before, during and after electrical tooth stimulation were investigate d in 25 Ferrets. The micropuncture technique was used to measure inter stitial fluid pressure and laser-Doppler flowmetry was used to record pulpal blood flow. Animals with an intact innervation (group 1) served as controls. Sensory denervation was by axotomy of the left inferior alveolar nerve 10 days before the experiment (group 2) and sympathecto my by removal of the left cervical ganglion 5 days before the experime nts (group 3). The study was designed to verify whether denervation af fected basal pulp blood flow and interstitial fluid pressures during c ontrol conditions and/or after tooth stimulation. During control condi tions the interstitial fluid pressure averaged 1.32 +/- 0.07 kPa in gr oup 1, whereas the mean was only 0.51 +/- 0.13 kPa in the axotomized a nimals (group 2). The difference was highly significant, indicating de creased blood or interstitial fluid volume in the pulp after inferior alveolar nerve axotomy. In the sympathectomized group neither the inte rstitial fluid pressure nor the pulp blood flow was significantly diff erent from those of group 1. Electrical tooth stimulation caused an al most simultaneous increase in interstitial fluid pressure and pulp blo od flow in groups 1 and 3, whereas stimulation did not significantly c hange either variable in the axotomized animals (group 2). It is concl uded that a resting nervous vasodilator tone of sensory origin exists in the ferret dental pulp, and that the sensory nerves are responsible for the increased interstitial fluid pressure and pulp blood flow dur ing tooth stimulation. (C) 1997 Elsevier Science Ltd.