In vivo determination of multiple indices of periodontal inflammation by optical spectroscopy

Abstract

Background and 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 non-invasively study periodontal inflammation. The study objective 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. Material and 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 successfully generate complex inflammatory profiles in periodontal tissues. Tissue oxygenation at periodontitis sites was 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 per se showed no significant difference between the sites but a water index associated with tissue electrolyte levels and temperature differed was significantly between periodontitis sites when compared to both healthy and gingivitis sites (p<0.03). Conclusion This study establishes 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, chair-side, site-specific, diagnostic and prognostic test for periodontitis.

Evaluation of the marginal fit at implant–abutment interface by optical coherence tomography

“…Pathological changes can affect the optical properties of periodontal tissue; it has been suggested that multiple inflammatory indices can be monitored in periodontal tissues by infrared spectroscopy. 45 Likewise, the attenuation coefficient of GN is expected to depend on such factors as blood flow, oxygen levels, health state, etc. Further investigation is necessary to determine how these factors affect OCT imaging through the oral mucosal tissue.…”

An Update on Novel Non‐Invasive Approaches for Periodontal Diagnosis

“…The extinction coefficient data for water were multiplied by a scaling factor of 10. (Reproduced with permission from Liu et al 68 )…”

Diagnosis and Monitoring of Gingivitis in vivo Using Non-Invasive Technology - Infrared Spectroscopy

“…Consequently, monitoring the intensity of the water bands in gingival tissues should p r o v i d e a n i n d e x o f t i s s u e h y d r a t i o n representing a simple indicator of inflammation at specific periodontal sites. Furthermore, we have recently demonstrated, using optical spectroscopy, that tissue oxygenation at gingivitis sites was significantly decreased (p<0.05) compared to healthy controls as shown in Figure 3 (Liu et al, 2009). Such decreased oxygen saturation likely reflects tissue hypoxia resulting from an ongoing inflammatory response leading to increased oxygen consumption (Hanioka et al, 2000).…”

“…The result is localized gingival anoxemia, which superimposes a somewhat bluish hue on the reddened gingiva (Hanioka et al, 1991). We have recently attempted to establish a model to predict risk index of gingivitis based on spectral data from several independent studies (Liu et al, 2009;Ge et al, 2011;Nogueira et al, 2011). The method of Fort and Lambert-Lacroix, using partial least squares with penalized logistic regression was applied directly to the measured visible reflectance spectrum (510 -620 nm) of the gum with a subject-out bootstrap cross validation approach to select classifier parameters.…”

“…In addition, tissue edema, an index that is commonly used as a marker of gingival inflammation (Loe et al, 1963;Scott et al, 2004) can also be measured using near infrared spectroscopy (Liu et al, 2009;Sowa et al, 2001). Consequently, monitoring the intensity of the water bands in gingival tissues should p r o v i d e a n i n d e x o f t i s s u e h y d r a t i o n representing a simple indicator of inflammation at specific periodontal sites.…”