Investigation of in vitro dental erosion by optical techniques

Abstract

Nitrogen laser-induced fluorescence (LIF) and tungsten halogen lamp excited diffuse reflectance spectra were recorded in 350- to 700-nm range on a miniature fiber-optic spectrometer from in vitro premolar tooth during various stages of artificial erosion with 36% phosphoric acid. Both the LIF spectral intensity and the diffuse reflectance intensity gradually increased during tooth erosion. The LIF spectra were analyzed by curve fitting using Gaussian spectral functions to determine the true contribution of different bands in the spectra during erosion. Thus, the broad bands at 440 and 490 nm in the LIF spectra of sound enamel were resolved into four peaks centered at 409.1, 438.1, 492.4 and 523.1 nm and of sound dentin into peaks at 412.0, 440.1, 487.8 and 523.4 nm. The F410/F525 ratios derived from curve-fitted Gaussian peak amplitudes and curve areas were found to be more sensitive to erosion as compared to the diffuse reflectance ratio R500/R700 or the raw LIF spectral ratio F440/F490.

Optical pen-size reflectometer for monitoring of early dental erosion in native and polished enamels

“…Linear decrease and increase of the backscattered light intensity during demineralization and remineralization processes were reported by Kishen et al 18 Change of the specular and diffuse reflection intensities during erosion progression was investigated in our previous in vitro studies. 19,20 Particularly, sharp decay of the specular reflection was observed already in the early stages of enamel erosion in vitro, while the less pronounced increase of the diffuse reflection intensity was measured, which correlated well with the results of Thomas et al 17 Further investigation revealed a strong correlation between the decrease of the specular reflection and continuous surface roughening. 19 Significant change of the specular reflection was detected even in eroded and abraded surfaces.…”

“…Fried et al demonstrated a new near-infrared (IR) reflectance imaging method 15,16 which could be potentially used for the clinical localization of the demineralized tissue. Thomas et al showed a gradual increase of the diffuse reflectance during tooth erosion, 17 though the sensitivity of the signal to erosive changes was poor. Linear decrease and increase of the backscattered light intensity during demineralization and remineralization processes were reported by Kishen et al 18 Change of the specular and diffuse reflection intensities during erosion progression was investigated in our previous in vitro studies.…”

Effects of enamel abrasion, salivary pellicle, and measurement angle on the optical assessment of dental erosion

“…The low sensitivity of the diffuse reflection analysis for in vitro erosion assessment was found in the former study 17 and was mentioned in another publication as well. 10 …”

“…Often, significant erosive tooth wear induces tooth hypersensitivity and requires expensive restorative therapies. 9 To improve the situation, much attention has been given to the development of new techniques, [10][11][12][13][14][15] which provide a quantitative assessment of dental erosion. Among the different varieties, optical diagnostic tools have certain advantages due to their noninvasive and nondestructive evaluation of dental tissues, and fast signal acquisition and data analysis.…”

“…For example, a fiber optic backscatter spectroscopic sensor was successfully applied to monitor in vitro enamel demineralization and remineralization. 16 Thomas et al 10 used another fiber optic setup to monitor change of the diffuse reflection spectra after demineralization of enamel and dentine samples. However, the authors concluded that the diffuse reflection signal had a low sensitivity for enamel etching.…”