Effects of bleaching on laser Doppler blood-flow signals recorded from human teeth in vitro.
OBJECTIVE
To determine if bleaching a tooth affects significantly laser Doppler recordings of pulpal blood flow that are made through the treated enamel and dentine.


METHODS
Recordings of blood flow (flux) were made with a laser-Doppler flow meter from the crowns of 14, recently extracted, human premolars while diluted blood was pumped at three different rates through a cannula that was inserted into the pulp cavity with its tip in the coronal pulp chamber. The recordings of flux were made before and after bleaching the crown with 38% hydrogen peroxide for 30min. The colour changes produced by bleaching were also measured with a digital spectrophotometer in 15 teeth. The effects of bleaching on both blood flow recordings and tooth colour were studied in 11 of the teeth.


RESULTS
Both before and after bleaching, there was a linear relationship between blood perfusion rate and flux. After bleaching, the flux readings increased by an average of 46%, and were significantly increased in every tooth (P<0.001, Wilcoxon Signed Rank Test). There was no significant correlation between the changes in flux and the changes in tooth colour.


CONCLUSIONS
A laser Doppler flow meter cannot be used to determine the effect of bleaching on pulpal blood flow in intact teeth.
Department of Stomatology, Faculty of Dentistry, Srinakharinwirot University, Bangkok 10500, Thailand. Electronic address: ajcharanukul@yahoo.com.
Orapin
O
Ajcharanukul
Department of Physiology and Pharmacology, School of Medical Sciences, University of Bristol, University Walk, Bristol BS8 1TD, UK.
Bruce
B
Matthews
D000328:Adult; D001641:Bicuspid / Q000098:blood supply / Q000187:drug effects; D003743:Dental Enamel / Q000187:drug effects; D003782:Dental Pulp / Q000098:blood supply* / Q000187:drug effects; D003786:Dental Pulp Cavity / Q000098:blood supply* / Q000187:drug effects; D003804:Dentin / Q000187:drug effects; D006801:Humans; D006861:Hydrogen Peroxide / Q000008:administration & dosage / Q000097:blood; D017078:Laser-Doppler Flowmetry / Q000295:instrumentation / Q000379:methods; D014073:Tooth Bleaching / Q000379:methods*; D019228:Tooth Crown / Q000098:blood supply / Q000187:drug effects; D014075:Tooth Discoloration; D055815:Young Adult
D006861:Hydrogen Peroxide
Dentine; Enamel; Pulp; Spectroscopy