Biochemical characterization of human gingival crevicular fluid during orthodontic tooth movement using Raman spectroscopy

Abstract

This study used Raman spectroscopy to report the first human gingival crevicular fluid (GCF) biochemical characterization during the early phase of orthodontic tooth movement. This technique allows for label-free and noninvasive biochemical change monitoring in GCF during orthodontic tooth movement. Ten orthodontic patients (20.8 ± 2.5 years) participated in the study. GCF samples were obtained before (baseline, 0 days) and during orthodontic treatment at 1, 7 and 28 days. For Raman spectroscopic measurement, GCF samples (5 µl) were deposited onto a gold-coated substrate, then dried at room temperature. Raman spectra GCF analysis during orthodontic treatment indicated that the hydroxyapatite to primarily collagen-dominated matrix band (phosphate 984 cm(-1)/amide I 1667 cm(-1)) intensity ratio decreased at day 7 (P < 0.05). The carbonate apatite to hydroxyapatite ratio (carbonate 1088 cm(-1)/phosphate 984 cm(-1)) was significantly higher on day 7 compared to day 0 (P < 0.05). These results indicate that demineralization occurs during the alveolar bone remodeling process. We also found notable peak shifts in the amide I range during orthodontic tooth movement. The 1658 cm(-1) in baseline red shifted to 1667 cm(-1) at orthodontic treatment day 7. Curve fitting in the amide I (1615-1725 cm(-1)) range demonstrated that increased random coil conformation was accompanied by a decrease in β-sheet structure during orthodontic tooth movement. Thus, we suggest Raman spectroscopy could be used for label-free, non-invasive GCF quality assessment during orthodontic tooth movement. Furthermore, this method may prove to be a powerful diagnostic and prognostic tool for monitoring orthodontic tooth movement in a clinical setting.

Monitoring early phases of orthodontic treatment by means of Raman spectroscopies

“…This behavior can be ascribed to changes in protein concentration. A similar effect has been observed by Jung et al, 31 and it is also expected because it is well known that orthodontic treatment induces inflammatory processes and changes in cytokines, enzyme, and metabolites concentrations. 1,4,5,[14][15][16][17] These changes are more intense immediately after the application of orthodontic forces and decrease over time.…”

“…In addition, the center of the amide I band shifts toward a lower wavenumber shift value (from 1641 to 1611 cm −1 ) reflecting changes in the protein configuration. 30 As far as concerns amide I band shift, Jung et al 31 noticed a spectral blueshift differently from us. 30,32 Moreover, observing T1, T2, and T3 spectra, a significant increase in the intensity of the modes at 1167, 1390, and 1577 cm −1 is found.…”

“…After an initial increase of the α-helix contribution at T1, a decrease at T2 and T3 is observed. The differences in the behavior of the amide I contributions at the different stages observed by Jung et al 31 could be ascribed to different GCF sampling and days of collection.…”

“…Recently, μ-RS has been used to assay GCF changes during the initial phases of orthodontic tooth movements. [30][31][32] In particular, Jung et al 31 investigated GCF samples obtained before and during an orthodontic treatment (before and after 2, 7, and 28 days from the beginning). They performed μ-RS measurements on a drop of GCF deposited on a gold-coated substrate using a 100-mW 785-nm diode laser source.…”

“…In fact, SERS technique can be extremely useful when samples are characterized by a low signal as in the case of GCF. [33][34][35][36][37] For this kind of measurement, we followed the same procedure of Jung et al 31 for extracting the fluid from paper cones, and we used substrates prepared with homemade gold nanoparticles (GNPs). 38 Furthermore, we widened our investigation on μ-RS measurements directly performed on impregnated paper cones to a large number of patients.…”