title: In Vivo Capillary Loop Hemoglobin Spectroscopy in Labial, Sublingual, and Periodontal Tissues.
abstract: OBJECTIVE
  Reproducible estimates of hemoglobin absorption spectra from human capillaroscopy images of arterioles, capillaries, and venules in sublingual and labial mucosa in vivo and venules in the tissues lining the periodontal pocket.
  
  
  METHODS
  By reducing the size of both the imaging lens and the light guide to a maximum 1 mm diameter and opposing them with a gap of 600 μm we have been able to transmit light through the loop of tissues which moves into the gap between the lens and light guide when these are placed in contact with the labial and sublingual oral mucosa. This allows in vivo transillumination of the microvessels supplying the mucosa.
  
  
  RESULTS
  Images from five volunteers showed similar patterns and the ratio of optical densities at 410 nm and 430 nm had a range from 2.5 at 90-100% saturation to 0.5 at zero % saturation. Measured optical density ratios ranged from 0.5 to 1.6 ± 0.1 in the afferent arm of the capillary loops and 0.5 to 1.1 ± 0.1 in the efferent arm of the capillary loops.
  
  
  CONCLUSIONS
  In vivo spectroscopic hemoglobin optical density ratios in oral mucosal microvessels show a qualitatively consistent result within the expected in vitro parameters.
authors.affiliation: Vascular Physiology Unit, Institute of Child Health, London, UK.
authors.forename: David
authors.initials: D
authors.lastname: Townsend
authors.affiliation: Periodontology Unit, UCL Eastman Dental Institute, UCL, University of London, London, UK.
authors.forename: Francesco
authors.initials: F
authors.lastname: D'Aiuto
authors.affiliation: Vascular Physiology Unit, Institute of Child Health, London, UK.
authors.forename: John
authors.initials: J
authors.lastname: Deanfield
mesh_terms: D000293:Adolescent; D000328:Adult; D002196:Capillaries / Q000378:metabolism*; D005260:Female; D006454:Hemoglobins / Q000378:metabolism*; D006801:Humans; D008046:Lip / Q000378:metabolism*; D008297:Male; D008875:Middle Aged; D009060:Mouth Floor / Q000378:metabolism*; D009061:Mouth Mucosa / Q000378:metabolism*; D010519:Periodontium / Q000378:metabolism*; D013056:Spectrophotometry, Ultraviolet / Q000379:methods
chemical_list: D006454:Hemoglobins
keywords: gradient index lens; hemoglobin spectroscopy; in vivo