In vivo Raman spectroscopic characteristics of different sites of the oral mucosa in healthy volunteers
Investigate the biochemistry of in vivo healthy oral tissues through Raman spectroscopy. We aimed to characterize the biochemical features of healthy condition in oral subsites (buccal mucosa, lip, tongue, and gingiva) of healthy subjects. More specifically, we investigated Raman spectral characteristics and biochemical content of in vivo healthy tissues on Brazilian population. This characterization can be used to better define normal tissue and improve the detection of oral premalignant conditions in future studies.
Materials and methods
For spectroscopic analysis a Raman spectrometer (Kaiser Optical Systems imaging spectrograph Holospec, f / 1.8i-NIR) coupled with a laser 785 nm, 60 mW was used. Raman measurements were obtained by means of an optical fiber (EMVision fiber optic probe) coupled between the laser and the spectrometer. Three spectra per site were acquired from the lip, buccal mucosa, tongue, and gingiva of ten healthy volunteers. This resulted in 30 spectra per oral sub-site and in total 120 spectra.
We report detailed biochemical information on these subsites and their relative composition based on deconvolution studies of their spectra. Finally, we also report classification efficiency of 61, 83, 41, and 93% for buccal, gingiva, lip, and tongue respectively after applying multivariate statistical tools.
We quantitated the contribution of various biochemicals in terms of percentage, and this will enable comparison not only across anatomical sites but also across studies. Raman spectroscopy can rapidly probe tissue biochemistry of healthy oral regions. Moreover, the study suggests the possibility of using Raman spectroscopy combined with signal processing and multivariate analysis methods to differentiate the oral sites in healthy conditions and compare with pathological conditions in future studies.
The spectral characterization of the healthy condition of oral tissues by a noninvasive, label-free, and real-time analytical techniques is important to create a spectral reference for future diagnosis of pathological conditions.
KeywordsIn vivo Oral pathology Clinical
The authors would like to acknowledge Eric Marple from EmVision LLC.
L. F. C. S. C. participated in the study design, spectra collection, manuscript writing, managed the data analysis, and paper final remarks; M.S.N. participated in manuscript writing and revision, data analysis, paper final remarks, carried out all the classification, and spectral pre- and post-processing presented in the section “Accuracy improvement by other normalization and classification methods”; T. B. participated in manuscript writing, data analysis, paper final remarks, and carried out the spectral deconvolution and fitting. L. P. M. N. carried out spectra collection, L. D. carried out spectra collection, T. O. M. participated in data analysis, R. R. carried out spectra collection, M. C. participated in the study design, A. A. M. participated in the study design, and L. E. S. S. participated in the paper final remarks.
The work was supported by the Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP-2014/05978-1) through Luis Felipe CS Carvalho’s scholarship. Luis Felipe das Chagas and Silva de Carvalho also thank FAPESP - 2018/03636-7, and Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) PNPD Odontologia - Universidade de Taubaté, and Centro Universitário Braz Cubas for the Scientific Initiation Program and Coordenação de Aperfeicoamento de Pessoal de Nível Superior (CAPES) through Tanmoy Bathacharjee’s scholarship.
Compliance with ethical standards
Conflict of interest
The authors declare that they have no conflict of interest.
All procedures performed in studies involving human participants were in accordance with the ethical standards of the institutional and/or national research committee and with the 1964 Helsinki declaration and its later amendments or comparable ethical standards. The study was approved by Research Ethics Committee of Universidade do Vale do Paraíba (UNIVAP) via Plataforma Brasil-Brazil (number 1132237-2015).
Informed consent was obtained from all individual participants included in the study.
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