On site noninvasive assessment of peri-implant inflammation by optical spectroscopy

Optical spectroscopy has been proposed to measure regional tissue hemodynamics in periodontal tissue. The objective of this study was to further evaluate the diagnostic potential of optical spectroscopy in peri-implant inflammation in vivo by assessing multiple inflammatory parameters (tissue oxygenation, total tissue hemoglobin, deoxyhemoglobin, oxygenated hemoglobin and tissue edema) simultaneously.

A cross-sectional study was performed in a total of 64 individuals who presented with dental implants in different stages of inflammation. In brief, visible-near-infrared spectra were obtained, processed and evaluated from healthy (n = 151), mucositis (n = 70) and peri-implantitis sites (n = 75) using a portable spectrometer. A modified Beer-Lambert unmixing model that incorporates a nonparametric scattering loss function was employed to determine the relative contribution of each inflammatory component to the overall spectrum.

Tissue oxygenation at peri-implantitis sites was significantly decreased (p < 0.05) when compared with that at healthy sites, which was largely due to an increase in deoxyhemoglobin and a decrease in oxyhemoglobin at the peri-implantitis sites compared with the mucositis and healthy sites. In addition, the tissue hydration index derived from the optical spectra in mucositis was significantly higher than that in other groups (p < 0.05).

In summary, the results of this study revealed that hemodynamic alterations can be detected around diseased peri-implant sites by optical spectroscopy, and this method may be considered an alternative and feasible approach for the monitoring and diagnosis of peri-implant diseases.