In vivo Determination of Periodontal Inflammation by Near Infrared Spectroscopy

Objective: The main objective for this study was to evaluate the ability of optical spectroscopy to simultaneously determine 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. Results: Optical spectroscopy determined that tissue oxygenation in periodontitis sites is significantly decreased (p<0.05) compared to gingivitis and healthy controls. This is largely due to an increase in deoxyhemoglobin in the periodontitis sites compared to healthy (p<0.01) and gingivitis (p=0.05) sites. Tissue water content showed no significant difference between the sites but a water index associated with tissue electrolyte levels and temperature was significantly different in periodontitis sites compared to both healthy and gingivitis sites (p<0.03). Conclusions: This study establishes that optical spectroscopy can simultaneously determine multiple inflammatory indices directly in the periodontal tissues in vivo in a non-invasive and reagent-free manner. Future studies will determine the potential of optical spectroscopy as a next generation diagnostic and prognostic tool for periodontal diseases. Additionally, optical spectroscopy may permit the standardization of clinical and sub-clinical inflammatory indices in periodontal research studies. (Supported by the Natural Sciences and Engineering Research Council of Canada and the Canadian Institutes for Health Research 311313104, and by the National Institute for Dental and Craniofacial Research, USA R21DE017160).