Influence of local insults on sympathetic vasoconstrictor control in feline dental pulp.

The present investigation was undertaken to ascertain whether local insults can affect the sympathetic vasoconstrictor regulation of pulpal blood flow. The rate of disapperance (k-value) of iodide from dentinal cavities was measured in anaesthetized cats. Changes in k-value reflected changes in blood flow. It has previously been shown that stimulation of sympathetic vasoconstrictor nerve fibres generally causes a clearcut decrease in the k-value. Deep cavity preparation was found to inhibit the vasoconstrictor response in a few cases in experiments on mature cats. Heating or cooling the tooth during cavity preparation induced a more frequent inhibition, which proved to be reversible within a few hours. Compound 48/80 applied locally to the cavity was also found to induce inhibition of the vasoconstrictor effect, but in this case no sign of reversibility was observed. Chronic insults were produced by exposing the cavity to oral microorganisms during 1-4 weeks before the experimental procedure. In this case, the sympathetic vasoconstrictor response was not inhibited. A histological study was performed to examine the pulp tissue after cavity preparation and the application of insults. It was found that cavity preparation and acute insults caused little or no disturbance, while chronic insults resulted in severe damage to the pulpal tissue.