Improvement of the detection of human pulpal blood flow using a laser Doppler flowmeter modified for low flow velocity

Abstract Objective Human pulpal blood flow (PBF) signals as measured by laser Doppler flowmeter (LDF) decrease with age. Although this decrease is considered to be due in part to slow blood flow, information regarding this velocity in humans has been lacking. The aims of the present study were to estimate the blood flow velocity in human dental pulp and to evaluate the validity of LDF modified for the measurement of slow blood flow. Design Mean blood flow velocities at the upper central incisor, gingiva, fingertip and forearm of 28 volunteers (mean age: 38.6 years old) were estimated using LDF with a frequency analyser. Blood flow signals at these measurement areas were recorded using two different LDFs: (a) one with a standard blood flow range; and (b) one modified for low blood flow velocity. Results The frequency range of the Doppler shift measured at the teeth with an opaque rubber dam was the narrowest (median: 4.3 kHz) among all of the measurement areas. The estimated mean blood flow velocity was the slowest at the teeth with a dam (median: 0.18 mm/s). LDF for low blood flow velocity detected larger and clearer pulsatile blood flow signals from the teeth with dams than did standard LDF. Conclusions The present results indicate that the velocity of PBF in humans is very low and that LDF modified for the measurement of slow blood flow is appropriate for PBF measurement in humans.