Effect of probe design on the suitability of laser Doppler flowmetry in vitality testing of human teeth

The aim of this investigation was to study the influence of probe design on the signal output from the dental pulp in experiments with laser Doppler flowmetry (LDF). Eighteen patients 14 to 39 years of age were examined. Recordings were made from a maxillary and a mandibular central incisor and a maxillary canine with an infrared laser Doppler flowmeter. The radiographic appearance of the tested teeth was within normal limits and all teeth responded normally to electric pulp testing (EPT). Five configurations of probes were used. Each probe had 3 fibers arranged in a triangle. One fiber carried the laser light to the pulp tissue and 2 fibers carried the backscattered light to the detector giving the signal output. The diameter of each of the 3 fibers in the probe was 200 microns except in 1 probe where the diameter of the fibers was 125 microns. The distance between the 3 fibers in the triangular arrangement in each probe was 250, 500, 800, 1000, and 1500 microns. A special rubber base splint was used to hold the probe in place on the buccal surface of the tested teeth. The output signals from the LDF were fed into an analog printer and a lap top computer where all calculations were done. The probe with the largest separation of the fibers produced significantly higher output signals from the maxillary and mandibular incisors than the other probes. The same probe also produced significantly higher output signals than the smaller probes from the maxillary canine with the exception of the 200/800 probe.(ABSTRACT TRUNCATED AT 250 WORDS)