title: 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.
  
  
  METHODS
  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: 4.3kHz) among all of the measurement areas. The estimated mean blood flow velocity was the slowest at the teeth with a dam (median: 0.18mm/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.
authors.affiliation: Division of Periodontology and Endodontology, Department of Oral Biology, Tohoku University Graduate School of Dentistry, 4-1 Seiryo-machi, Aoba-ku, Sendai 980-8575, Japan; Dalian Stomatological Hospital, Changjiang Road 935, Shahekou District, Dalian 116021, China.
authors.forename: Xiaofu
authors.initials: X
authors.lastname: Qu
authors.affiliation: Division of Periodontology and Endodontology, Department of Oral Biology, Tohoku University Graduate School of Dentistry, 4-1 Seiryo-machi, Aoba-ku, Sendai 980-8575, Japan. Electronic address: ikawa@dent.tohoku.ac.jp.
authors.forename: Motohide
authors.initials: M
authors.lastname: Ikawa
authors.affiliation: Division of Periodontology and Endodontology, Department of Oral Biology, Tohoku University Graduate School of Dentistry, 4-1 Seiryo-machi, Aoba-ku, Sendai 980-8575, Japan.
authors.forename: Hidetoshi
authors.initials: H
authors.lastname: Shimauchi
mesh_terms: D000328:Adult; D001783:Blood Flow Velocity / Q000502:physiology; D003782:Dental Pulp / Q000098:blood supply*; D004867:Equipment Design; D006801:Humans; D017078:Laser-Doppler Flowmetry / Q000295:instrumentation*; D008875:Middle Aged; D012039:Regional Blood Flow / Q000502:physiology
keywords: Blood flow; Human; Laser Doppler; Pulp