<title>Comparative laser Doppler measurement on tooth pulp blood flow at 632 and 750 nm</title>

Abstract

Laser-Doppler flowmetry has been used for the assessment of pulp blood flow in health and disease. General purpose laser Doppler instruments working at the Helium-Neon (632,8 nm) as well as infrared (750-810 nm) wavelengths have been used in this application. Specially designed handheld equipment has also been used to assess blood supply to the tooth. A considerable difference in the measurement results have been noticed when using different wavelengths and probe designs. In this study some of the problems related to the use of various wavelengths and probe designs are studied in human teeth and in a physical model of a tooth. Our results support the early observation that measurements at different wavelengths and with different probe designs cannot be directly compared. The result can be explained by the strong differences in absorption and scattering properties of the enamel and dentine at the two wavelengths used .The photon flux through the tooth and the pulp is strongly affected by the fibre optic configuration chosen which also explains the measurement variability when different probe designs are used.