Discrimination of Dental Caries Using Colorimetric Characteristics of Fluorescence Spectrum

Abstract

The feasibility of colorimetric parameters for the discrimination of the stages of dental caries based on a light-induced autofluorescence spectrum at a 405-nm excitation wavelength was investigated. The fluorescence spectra of 4 groups of tooth samples (10 sound, 10 early-stage decay, 14 established decay, and 10 severe decay), which were classified by the International Caries Detection and Assessment System, were experimentally measured in vitro. The carious lesion samples had an additional fluorescence peak at around 627 nm. The mathematical relation of the fluorescence spectrum and human color perception was established and computed. With increasing severity, the fluorescence color changed from green to yellow according to the colorimetric parameters of the CIE 1931 (x, y) chromaticity coordinates and dominant wavelengths. The results from a one-way ANOVA of the dominant wavelength showed a statistically significant difference among the 4 classified groups. The colorimetric parameters of the light-induced fluorescence spectrum can potentially be applied to evaluate the various carious levels.

Development of a Fluorescence-Based Caries Scoring System for an Intraoral Scanner: An in vitro Study

“…These components were inserted into different mathematical functions (f x ) used to quantify the fluorescence signal with a single parameter, upon which a caries scoring system for the scanner prototype could be based. A total of 4 functions were investigated in this study, inspired by functions used in commercially available 2D fluorescence imaging devices [Kühnisch et al, 2006;Thoms, 2006;Chen et al, 2015;Jung et al, 2018], albeit with modifications. These functions and their rationale are described below.…”

“…Since the G fluorescence signal alone has also been shown to be an indicator for the level of demineralization in hard dental tissues [Borisova et al, 2006;Gmür et al, 2006;Pretty, 2006;Chen et al, 2015], f 2 was defined to represent the absolute G fluorescence signal measured at the examination sites.…”

“…When the sound tooth surface is illuminated with violet/blue light, part of the light is absorbed by fluorophores present in enamel and dentin, and reemitted at a longer wavelength as green fluorescent light [Monici, 2005]. When demineralization of the hard dental tissues occurs due to caries, the intensity of the green fluorescence from the lesion's surface is reduced: therefore, caries lesions appear darker on fluorescence images [Borisova et al, 2006;Gmür et al, 2006;Pretty, 2006;Chen et al, 2015]. At the same time, metabolites from the cariogenic bacteria, that is, porphyrins, emit red fluorescence when excited with violet/blue light [Borisova et al, 2006;Kim and Kim, 2017].…”

“…At the same time, metabolites from the cariogenic bacteria, that is, porphyrins, emit red fluorescence when excited with violet/blue light [Borisova et al, 2006;Kim and Kim, 2017]. By analyzing the fluorescence signal and the ratio change between red and green fluorescence from the hard dental tissues, information about the presence and progression of caries lesions can be gained [Borisova et al, 2006;Thoms, 2006;Jablonski-Momeni et al, 2011b;Chen et al, 2015;Jung et al, 2018].…”

Red fluorescence of dental biofilm as an indicator for assessing the efficacy of antimicrobials

“…8,9 The porphyrin derivatives have previously been held responsible for fluorescence emission in the red spectral region of dental biofilm and caries lesions when excited with 405 nm violet light. 10 The porphyrin concentration is high in Gram-negative oral bacteria, which indicates the observed RF was produced by mature and pathogenic biofilms. Also, previous studies have reported that the intensity of RF increased with the biofilm maturation and its pathogenicity.…”