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

Abstract

<b><i>Objectives:</i></b> To develop an automated fluorescence-based caries scoring system for an intraoral scanner and to<i></i>test the performance of the system compared to state-of-the-art methods. <b><i>Methods:</i></b> Seventy-three permanent posterior teeth were scanned with a three-dimensional (3D) intraoral scanner prototype which emitted light at 415 nm. An overlay representing the fluorescence signal from the tissue was mapped onto 3D models of the teeth. Multiple examination sites (<i>n</i> = 139) on the occlusal surfaces were chosen, and their red and green fluorescence signal components were extracted. These components were used to calculate 4 mathematical functions upon which a caries scoring system for the scanner prototype could be based. Visual-tactile (International Caries Detection and Assessment System, ICDAS), radiographic (ICDAS), and histological assessments were conducted on the same examination sites. <b><i>Results:</i></b> Most index tests showed significant correlation with histology. The strongest correlation was observed for the visual-tactile examination (<i>r</i><sub>s</sub> = 0.80) followed by the scanner supported by the caries classification function that quantifies the overall fluorescence compared to sound surfaces (<i>r</i><sub>s</sub> = 0.78). Additionally, this function resulted in the highest intra-examiner reliability (κ = 0.964), and the highest sum of sensitivity (SE) and specificity (SP) (sum SE-SP: 1.60–1.84) at the 2 histological levels where the comparison with visual-tactile assessment was possible (κ = 0.886, sum SE-SP = 1.57–1.81) and at the 3 out of 4 histological levels where the comparison with radiographic assessment was possible (κ = 0.911, sum SE-SP = 1.37–1.78); the only exception was for the lesions in the outer third of dentin, where the radiographic assessment showed the highest sum SE-SP (1.78). <b><i>Conclusion:</i></b> A fluorescence-based caries scoring system was developed for the intraoral scanner showing promising performance compared to state-of-the-art caries detection methods. The intraoral scanner accompanied by an automated caries scoring system may improve objective caries detection and increase the efficiency and effectiveness of oral examinations. Furthermore, this device has the potential to support reliable monitoring of early caries lesions.

Automated Caries Detection using a 3D Intraoral Scanner. An in Vivo Validation Study

“…Four different algorithms (ALG1-ALG4) developed for caries detection and classification on the 3D models were assessed. An article describing the development of the first three algorithms (ALG1-ALG3) was published previously by Michou et al 1 . Mathematical functions f 2f 4 of the mentioned study correspond to ALG1-ALG3 in the current study.…”

“…The use of 3D intraoral scanners (IOS) and corresponding software for oral disease detection and monitoring has proven potential [1][2][3][4][5] . There is increasing development in this area, both by companies that produce medical devices, and by researchers seeking improved devices and software that can support automated detection and objective monitoring of oral diseases such as caries, tooth wear and periodontal diseases either in a clinical setup or remotely [1][2][3][4][5][6][7][8][9][10][11][12] .…”

“…In a previous study, we investigated the implementation and diagnostic performance of an automated caries scoring system based on the fluorescence method using blue-violet light (415 nm wavelength) in a 3D IOS system (TRIOS 3, 3Shape TRIOS A/S, Denmark) 1 . Different caries classification algorithms were investigated for this fluorescence-based IOS system, showing good in vitro diagnostic performance when assessing occlusal caries lesions.…”

“…The only exception was observed for the caries lesions located in the outer third of dentin, where the radiographic assessment showed a higher value (SE+SP = 1.78) compared to the best-performing IOS algorithms (SE+SP = 1.67-1.69). In that study, both visual-tactile and radiographic assessments employed the International Caries Detection and Classification System criteria (ICDAS) 1,13 . The idea behind the development of the automated caries detection and classification system to accompany the 3D IOS is that by combining a method similar to the well-documented Quantitative Light-Induced Fluorescence (QLF) 6,8,14,15 with the 3D information provided by the IOS, detection and monitoring of the caries lesions can potentially be improved.…”

“…The study mentioned above 1 and later investigations led to the development of different algorithms for an automated caries scoring system, and its implementation in a prototype software accompanying the 3D IOS (TRIOS 4, 3Shape TRIOS A/S, Denmark). These algorithms employ red and green fluorescence (R f luo , G f luo ) signal 1 resulting from scanning with light at 415 nm.…”