Effects of cooling and heating of the tooth on pulpal blood flow in man

Laser Doppler flowmetry (LDF) was used to study the changes in pulpal blood flow (PBF) evoked by application of cold or heat to the palatinal surfaces of teeth 11 or 21 in nine young subjects. Switching from a thermode temperature of 33 degrees C to 5 degrees C on average induced a slow decrease of PBF to about 80% of control, and also warming to 39 degrees C evoked a small reduction in most subjects. Interindividual differences were large, however, and both cooling and warming sometimes triggered a rise in PBF. In contrast, skin blood flow, as recorded with LDF in the forearm, invariably rose during warming and fell during local cooling. The results suggested a more complex interaction between local and nervously mediated effects of moderate changes in temperature in the tooth pulp than skin, and that the previously held view of cold and heat decreasing and increasing PBF, respectively, is wrong.