Periodontitis-specific molecular signatures in gingival crevicular fluid.

BACKGROUND AND OBJECTIVE: Periodontitis is currently diagnosed almost entirely on gross clinical manifestations that have been in situ for more than 50 years without significant improvement. The general objective of this study was, therefore, to evaluate whether mid-infrared spectroscopy can be used to identify disease-specific molecular alterations to the overall biochemical profile of tissues and body fluids. MATERIAL AND METHODS: A total of 190 gingival crevicular fluid samples were obtained from periodontitis (n = 64), gingivitis (n = 61) and normal sites (n = 65). Corresponding infrared absorption spectra of gingival crevicular fluid samples were acquired and processed, and the relative contributions of key functional groups in the infrared spectra were analysed. The qualitative assessment of clinical relevance of these gingival crevicular fluid spectra was interpreted with the multivariate statistical analysis-linear discriminant analysis. RESULTS: Using infrared spectroscopy, we have been able to identify four molecular signatures (representing vibrations in amide I, amide II/tyrosine rings and symmetric and asymmetric PO2- stretching vibrations of phosphodiester groups in DNA) in the gingival crevicular fluid of subjects with periodontitis or gingivitis and healthy control subjects that clearly demarcate healthy and diseased periodontal tissues. Furthermore, the diagnostic accuracy for distinction between periodontally healthy and periodontitis sites revealed by multivariate classification of gingival crevicular fluid spectra was 98.4% for a training set of samples and 93.1% for a validation set. CONCLUSION: We have established that mid-infrared spectroscopy can be used to identify periodontitis-specific molecular signatures in gingival crevicular fluid and to confirm clinical diagnoses. Future longitudinal studies will assess whether mid-infrared spectroscopy represents a potential prognostic tool, recognized as key to advancement of periodontics.

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

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 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. 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 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). CONCLUSION: 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.