Comparison of two laser Doppler systems on the measurement of blood flow of premolar teeth under different pulpal conditions.

An in vivo investigation was conducted to assess the ability of two laser Doppler flowmeters (DRT4, Moor Instruments Ltd; Laserflo BPM2, Vasamedics) to differentiate between vital pulp, ischaemically necrosed pulp, and an empty pulp chamber in premolar teeth in children. Sixteen intact, vital teeth in need of extraction for orthodontic purposes were identified. Laser Doppler blood flow readings were taken prior to (T1) and after the administration of adrenaline-free local anaesthetic (T2), after extraction and replantation of the teeth (T3), and after broaching the pulp tissue and replanting the teeth (T4). The data collected (flux values) for both instruments were analysed using a repeated measures ANOVA. Significant differences were found for vital pulp (T1, T2) versus ischaemically necrosed pulp (T3), and for vital pulp (T1, T2) versus an empty pulp chamber (T4), with the Moor DRT4 instrument. This instrument also detected a significant difference in pulpal blood flow to the vital pulp, before and after the administration of local anaesthetic. No other significant differences were found.