Measurement of pulpal blood flow in dogs with nonradioactive colored microspheres

The viability of dental pulp depends largely on regional blood flow, as in other organs. Measurement of absolute pulpal blood flow (PBF) and comparisons with blood flow in other organs allow the prediction of microvascular regulation in dental pulp. In previous studies, PBF was measured in dogs mainly with radioactive microspheres. However, this established technique is inaccessible to many investigators due to concerns over radiation safety and radioactive waste. To overcome these limitations, a new method has been introduced that involves the use of nonradioactive colored microspheres for measuring regional blood flow in the myocardium and in other organs in animals. However, no previous studies have investigated the use of this method to measure PBF in dogs. We attempted to determine whether blood flow in dental pulp, which comprises a small amount of the total tissue in dogs, could be measured using this technique by comparing the measured values with those for regional myocardial blood flow. Mean blood flow values were between 0.148 and 0.182 ml/min/g for dental pulp at four different sites and about 1.0 ml/min/g in regional myocardium. These values are comparable to those previously reported using radioactive microspheres. As nonradioactive colored microspheres safety permitted measurement of absolute PBF in dogs, this technique appears to be useful for research into microvascular blood flow in dental pulp.