title: In vivo determination of multiple indices of periodontal inflammation by optical spectroscopy.
abstract: OBJECTIVE
  Visible, near-infrared (optical) spectroscopy can be used to measure regional tissue hemodynamics and edema and therefore may represent an ideal tool with which to study periodontal inflammation in a noninvasive manner. The study objective was to evaluate the ability of optical spectroscopy to determine simultaneously multiple inflammatory indices (tissue oxygenation, total tissue hemoglobin, deoxyhemoglobin, oxygenated hemoglobin and tissue edema) in periodontal tissues in vivo.
  
  
  METHODS
  Spectra were obtained, processed and evaluated from healthy, gingivitis and periodontitis sites (n = 133) using a portable optical, near-infrared spectrometer. A modified Beer-Lambert unmixing model that incorporates a nonparametric scattering loss function was used to determine the relative contribution of each inflammatory component to the overall spectrum.
  
  
  RESULTS
  Optical spectroscopy was harnessed to generate complex inflammatory profiles of periodontal tissues. Tissue oxygenation at periodontitis sites was significantly decreased (p < 0.05) compared to sites with gingivitis and healthy controls. This was largely the result of an increase in deoxyhemoglobin in the periodontitis sites compared with healthy (p < 0.01) and gingivitis (p = 0.05) sites. Tissue water content per se showed no significant difference between the sites, but a water index associated with tissue electrolyte levels and temperature differed significantly between periodontitis sites and both healthy and gingivitis sites (p < 0.03).
  
  
  CONCLUSIONS
  This study established that optical spectroscopy can simultaneously determine multiple inflammatory indices directly in the periodontal tissues in vivo. Visible, near-infrared spectroscopy has the potential to be developed into a simple, reagent-free, user-friendly, chairside, site-specific, diagnostic and prognostic test for periodontitis.
authors.affiliation: Institute for Biodiagnostics, National Research Council of Canada, Winnipeg, MB, Canada. kan-zhi.liu@nrc-cnrc.gc.ca
authors.forename: K Z
authors.initials: KZ
authors.lastname: Liu
authors.forename: X M
authors.initials: XM
authors.lastname: Xiang
authors.forename: A
authors.initials: A
authors.lastname: Man
authors.forename: M G
authors.initials: MG
authors.lastname: Sowa
authors.forename: A
authors.initials: A
authors.lastname: Cholakis
authors.forename: E
authors.initials: E
authors.lastname: Ghiabi
authors.forename: D L
authors.initials: DL
authors.lastname: Singer
authors.forename: D A
authors.initials: DA
authors.lastname: Scott
mesh_terms: D001831:Body Temperature / Q000502:physiology; D001834:Body Water / Q000737:chemistry; D055113:Chronic Periodontitis / Q000097:blood / Q000175:diagnosis* / Q000473:pathology; D004487:Edema / Q000097:blood / Q000175:diagnosis / Q000473:pathology; D005260:Female; D005884:Gingival Hemorrhage / Q000473:pathology; D005891:Gingivitis / Q000097:blood / Q000175:diagnosis / Q000473:pathology; D006454:Hemoglobins / Q000032:analysis; D006801:Humans; D008297:Male; D008875:Middle Aged; D010101:Oxygen Consumption / Q000502:physiology; D010108:Oxyhemoglobins / Q000032:analysis; D017622:Periodontal Attachment Loss / Q000473:pathology; D010512:Periodontal Index; D010514:Periodontal Pocket / Q000473:pathology; D010519:Periodontium / Q000378:metabolism / Q000473:pathology; D019265:Spectroscopy, Near-Infrared / Q000379:methods*; D014882:Water-Electrolyte Balance / Q000502:physiology
chemical_list: D006454:Hemoglobins; D010108:Oxyhemoglobins; C100003:deoxyhemoglobin