Measurement of blood flow in the dental pulp of dogs with the 133xenon washout method.

Following rapid injection of 133Xe into the maxillary artery, the radioactivity from a dog canine tooth was monitored with a specially-designed scintillation probe connected to a multichannel analyser. With a PDP 11/10 minicomputer, the semilogarithmic radioactivity-time curve was resolved into a fast component and a slow component using best fit least-square lines and the exponential rate constant (k) was determined for each component. The blood flow per unit of pulp mass (Q, in ml/min per 100 g) was obtained using the equation: Q = k X lambda tb, where lambda tb is the tissue-blood partition coefficient of 133Xe in the pulp determined for the haematocrit value of the individual experiments. The fast-component blood flow was 53.12 +/- 3.12 and the slow-component blood flow was 8.86 +/- 0.53 ml/min per 100 g (mean +/- SEM, n = 21). Although the exact anatomical areas for the fast and slow components are yet to be determined, the results show heterogeneity of blood flow in the pulp. The study showed that pulp blood flow in an intact tooth can be measured with the 133Xe washout method; the method enables study of circulatory physiology of the pulp in health and disease.