Effect of Imaging Geometry on Evaluating Natural White-Spot Lesions Using Quantitative Light-Induced Fluorescence

Diagnostic validity of ICDAS clinical criteria on digital 3D models

OBJECTIVE

To assess the diagnostic validity of ICDAS clinical criteria on 3D dental models from intraoral scanning.

METHODS

This is a retrospective analysis on part of the baseline sample collected in a cohort study and included 73 participants (12-19 years) from Denmark and Greece. The assessment was made by visual inspection, and then by visual inspection associated with radiographs. All participants were scanned with TRIOS 4 which uses white light to obtain the 3D models with tooth color, as well as blue light source (415 nm) for fluorescence. The 3D models' evaluation was conducted using tooth-color texture and subsequently fluorescence. Two scores were obtained for the 3D model examination: i) ICDAS based on tooth-color information; ii) ICDAS based on tooth-color information supplemented with fluorescence. For the analysis, weighted kappa, sensitivity (SE), specificity (SP) and accuracy (ACC) were calculated.

RESULTS

Regarding all lesions the values for SE, SP, and ACC were respectively 0.804, 0.801, and 0.802 for tooth-color, and 0.819, 0.808, and 0.810 for tooth-color supplemented with fluorescence. In terms of accuracy parameters for moderate-extensive lesions, the values for SE, SP, and ACC for tooth color were 0.709, 0.948, and 0.944, while for fluorescence they were 0.815, 0.937, and 0.934.

CONCLUSION

Caries assessment with ICDAS criteria on 3D dental models produces reliable scores. Visual caries analysis using 3D models demonstrates commendable diagnostic accuracy and reasonable consistency with traditional methods. The use of intraoral scanners may be beneficial in evaluating occlusal caries.

CLINICAL SIGNIFICANCE

The importance of this study is to prove the diagnostic accuracy of caries lesions diagnosis made using and intraoral scanner and to offer greater confidence to professionals who use this diagnosis tool in their daily clinical practice. Intraoral scanners demonstrate to be an accurate tool for diagnosing occlusal caries.

Comparison of biofilm models for producing artificial active white spot lesions

OBJECTIVE

This study compared three protocols for developing artificial white spot lesions (WSL) using biofilm models.

METHODOLOGY

In total, 45 human enamel specimens were sterilized and allocated into three groups based on the biofilm model: Streptococcus sobrinus and Lactobacillus casei (Ss+Lc), Streptococcus sobrinus (Ss), or Streptococcus mutans (Sm). Specimens were incubated in filter-sterilized human saliva to form the acquired pellicle and then subjected to the biofilm challenge consisting of three days of incubation with bacteria (for demineralization) and one day of remineralization, which was performed once for Ss+Lc (four days total), four times for Ss (16 days total), and three times for Sm (12 days total). After WSL creation, the lesion fluorescence, depth, and chemical composition were assessed using Quantitative Light-induced Fluorescence (QLF), Polarized Light Microscopy (PLM), and Raman Spectroscopy, respectively. Statistical analysis consisted of two-way ANOVA followed by Tukey's post hoc test (α=0.05). WSL created using the Ss+Lc protocol presented statistically significant higher fluorescence loss (ΔF) and integrated fluorescence (ΔQ) in comparison to the other two protocols (p<0.001).

RESULTS

In addition, Ss+Lc resulted in significantly deeper WSL (137.5 µm), followed by Ss (84.1 µm) and Sm (54.9 µm) (p<0.001). While high mineral content was observed in sound enamel surrounding the WSL, lesions created with the Ss+Lc protocol showed the highest demineralization level and changes in the mineral content among the three protocols.

CONCLUSION

The biofilm model using S. sobrinus and L. casei for four days was the most appropriate and simplified protocol for developing artificial active WSL with lower fluorescence, higher demineralization, and greater depth.

Occlusal caries detection and monitoring using a 3D intraoral scanner system. An in vivo assessment

OBJECTIVE

To assess the agreement in detecting and monitoring occlusal caries over thirty months using conventional visual and radiographic assessment and an intraoral scanner system which supports automated caries scoring.

METHODS

Ninety-one young participants aged 12-19 years were included in the study. All occlusal surfaces were examined visually, radiographically (when indicated), and scanned with the TRIOS 4 intraoral scanner. TRIOS Patient Monitoring software (vers. 2.3, 3Shape TRIOS A/S, Denmark) was used for automated caries detection on the 3D digital models.

RESULTS

Fifty-five of the study participants were re-examined after 30-months. Significant differences regarding caries detection were found between the conventional methods and the automated caries scoring system (p < 0.01), with moderate positive percent agreement (49-61%) and high negative percent agreement (87-98%). All methods reported significant caries progression over the follow-up period (p < 0.01). However, the automated system showed significantly more caries progression than the other methods (p < 0.01).

CONCLUSIONS

The software for automated caries detection and classification showed moderate positive agreement and strong negative agreement with the conventional methods considering both the baseline and the follow-up assessments. The automated caries scoring system detected significantly fewer caries lesions and tended to underestimate the caries severity. All methods indicated significant caries progression over the follow-up period, while the automated system detected more caries progression.

CLINICAL SIGNIFICANCE

The TRIOS system supporting automated occlusal caries detection and classification can assist in detecting and monitoring occlusal caries on permanent teeth as a complementary tool to the conventional methods. However, the operator should be aware that the automated system shows a tendency to underestimate the caries presence and lesion severity.

Impact of angle on photothermal radiometry and modulated luminescence (PTR/LUM) value

OBJECTIVE

To evaluate the impact of scanning angles to detect/quantify non-cavitated caries by photothermal-radiometry and modulated-luminescence (PTR/LUM, Canary System) and to evaluate the association of PTR/LUM value with lesion depth (LD), including sound tissue thickness under the lesion (ST).

METHODS

Thirty human extracted premolars were selected based on micro-computed tomography [μ-CT: sound (n=12), lesions into outer-half of enamel (n=6), lesions into inner-half of enamel (n=6), lesions into outer one-third of dentine (n=6)]. Each tooth sample was scanned 90° directly contacted to the center of non-cavitated lesion or sound smooth surface, and tilted 10° and 20° in four directions: buccal/lingual/occlusal/cervical. The procedure was repeated 48 h later. Lesion depth and ST [ST=5000 µm (maximum PTR/LUM scanning depth)-LD] were measured at the same scanning direction on μ-CT images. Sensitivity, specificity, area under the Receiver Operating Characteristic curve (AUC), and intraclass correlation coefficients (ICC) for different scanning angles were calculated. Sensitivity was further evaluated based on lesion extensions. Relationships between PTR/LUM value and lesion depth, and between PTR/LUM value and LD/ST-Ratio were evaluated.

RESULTS

PTR/LUM value showed significant differences among scanning angles. Overall sensitivity (78%-89%), specificity (66%-87%), AUC (0.86-0.92) and ICC (0.89-0.99), sensitivity based on lesion extensions presented no significant differences among angles. PTR/LUM value showed moderate correlations (0.56-0.74) with deepest lesion depth and LD/ST-Ratios.

CONCLUSION

The scanning angle within 20° increments might impact PTR/LUM value statistically; however, it did not affect PTR/LUM detection performance. PTR/LUM values were positively correlated with non-cavitated lesion depth, and not affected by sound tissue thickness under the lesion.

CLINICAL SIGNIFICANCE

Clinically, it is challenging to measure/scan at the same location and same angle longitudinally, however, it is important to standardize these parameters. Scanning within 20° deviation from perpendicular did not affect detection performance of PTR/LUM, and PTR/LUM value showed positive moderate correlation with caries depth.

Automated caries detection in vivo using a 3D intraoral scanner

The use of 3D intraoral scanners (IOS) and software that can support automated detection and objective monitoring of oral diseases such as caries, tooth wear or periodontal diseases, is increasingly receiving attention from researchers and industry. This study clinically validates an automated caries scoring system for occlusal caries detection and classification, previously defined for an IOS system featuring fluorescence (TRIOS 4, 3Shape TRIOS A/S, Denmark). Four algorithms (ALG1, ALG2, ALG3, ALG4) are assessed for the IOS; the first three are based only on fluorescence information, while ALG4 also takes into account the tooth color information. The diagnostic performance of these automated algorithms is compared with the diagnostic performance of the clinical visual examination, while histological assessment is used as reference. Additionally, possible differences between in vitro and in vivo diagnostic performance of the IOS system are investigated. The algorithms show comparable in vivo diagnostic performance to the visual examination with no significant difference in the area under the ROC curves (\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$p>0.05$$\end{document}p>0.05). Only minor differences between their in vitro and in vivo diagnostic performance are noted but no significant differences in the area under the ROC curves, (\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$p>0.05$$\end{document}p>0.05). This novel IOS system exhibits encouraging performance for clinical application on occlusal caries detection and classification. Different approaches can be investigated for possible optimization of the system.

High contrast imaging of dental fluorosis in the short wavelength infrared

Dental fluorosis is an increasing problem due to over exposure to fluoride from the environment. Fluorosis causes hypomineralization of the enamel during tooth development and mild fluorosis is visible as faint white lines on the tooth surface while the most severe fluorosis can result in pitted surfaces. It is difficult to quantify the severity of mild to moderate fluorosis and assessments are limited to subjective visual examinations. Dental fluorosis appears with very high contrast at short wavelength infrared (SWIR) wavelengths beyond 1400 nm and we hypothesize that these wavelengths may be better suited for detecting mild fluorosis and for estimating the severity on tooth surfaces. In this study, the contrast of fluorosis of varying severity on extracted human permanent teeth was measured at SWIR wavelengths ranging from 1300 to 2150 nm using an extended range of InGaAs camera and broadband light sources. The contrast was also measured in the visible range and with quantitative light-induced fluorescence (QLF) for comparison. The depth of hypomineralization and the integrated reflectivity were also measured with cross-polarization optical coherence tomography. The contrast of hypomineralization is significantly higher (P < 0.05) at 1460 and 1950 nm wavelengths than for the visible, fluorescence or other SWIR wavelengths from 1300 to 2150 nm. The highest correlation of the contrast with the depth of hypomineralization measured with cross-polarization-optical coherence tomography (CP-OCT) was at 1950 nm. This SWIR in vitro imaging study exploring wavelengths beyond 1400 nm has shown that hypomineralization on tooth surfaces can be viewed with extremely high contrast at SWIR wavelengths from 1460 to 2000 nm and that SWIR imaging has great potential for monitoring hypomineralization on tooth surfaces. New clinical methods are needed for the measurement of fluorosis that are valid, reliable, and feasible for surveillance at the community level. In addition, methods are needed for the quantitative assessment of fluorosis in vivo.

Monitoring enamel caries on resin-treated occlusal surfaces using quantitative light-induced fluorescence: an in vitro study

The aim of this study is to evaluate the ability of quantitative light-induced fluorescence (QLF) to monitor enamel caries lesions of different severity stages located on the occlusal surfaces of permanent teeth before and after treatment with resin infiltrant. Sixty extracted permanent teeth had one occlusal site selected and were categorized according to the International Caries Detection and Assessment System (ICDAS) criteria. The teeth were divided into three groups (n = 20): ICDAS 1, ICDAS 2, and ICDAS 3. The teeth were assessed by a trained examiner using QLF in two phases: (A) before and (B) after treatment with resin infiltrant. The caries lesions were evaluated using the following QLF parameters: area (mm²); ΔF, fluorescence loss (%); and ΔQ, fluorescence loss integrated over the lesion area (%*mm²). The resin infiltrant (Icon™) was applied on the occlusal surface following the manufacturer's recommendations. The teeth were then sectioned and prepared for polarized light microscopy analysis. The penetration of resin infiltrant was measured with ImageJ. The groups showed a statistically significant difference in all QLF parameters before and after caries infiltration, with the reduction of fluorescence values posttreatment (p < 0.05). Infiltrant penetration was observed in all groups, with a statistical difference between all groups (p < 0.05). The reduction in QLF parameters after resin infiltration suggests that QLF is able to monitor enamel caries lesions of different severity stages located on the occlusal surfaces of permanent teeth before and after treatment with resin infiltrant.

The reproducibility of assessment of white spot lesions adjacent to orthodontic brackets, with a quantitative light induced fluorescence digital camera at different rotations of teeth - an in vitro study

Background

A quantitative light-induced fluorescence digital (QLF-D) camera is able to assess demineralizations adjacent to orthodontic brackets. Rotations of teeth during and the presence of the orthodontic appliances may influence the longitudinal follow-up of such lesions over time.

Methods

Brackets were bonded on extracted teeth: 54 incisors and 31 canines. Demineralizations were formed in vitro directly cervical of the bracket. Images were captured using a QLF-D camera mounted on an optical bench, equipped with a goniometer on a turntable. The teeth were placed in the goniometer simulating buccolingual rotation (0°, 10°, 20°), the turn-table was used for mesiodistal rotations (0°, 10°, 20°). Standardized QLF-D images were made before (with and without a wire) and after debonding at combinations of aforementioned angles of rotation. The image after debonding at 0° buccolingual and 0° mesiodistal rotation served as a control.

Results

The presence of a bracket resulted in a significantly higher fluorescence loss, yet a smaller lesion area (p < 0.05) in comparison to the control. A significant higher fluorescence loss was seen for rotations towards lingual relative to the 0° buccolingual and 0° mesiodistal rotation, while the effect was less explicit towards buccal.

Conclusions

Fluorescence loss and lesion size are influenced by the angle of rotation under which the demineralization is photographed. The full extent of demineralizations is only apparent after debonding when photographed at rotations of 0° mesiodistal and up to 20° buccal. Precaution must be taken into account assessing demineralizations of patients undergoing treatment with fixed appliances when using a QLF-D camera.

Electronic supplementary material

The online version of this article (10.1186/s12903-018-0667-3) contains supplementary material, which is available to authorized users.

Association between quantitative measures obtained using fluorescence-based methods and activity status of occlusal caries lesions in primary molars

BACKGROUND

Fluorescence-based methods (FBM) can add objectiveness to diagnosis strategy for caries. Few studies, however, have focused on the evaluation of caries activity.

AIM

To evaluate the association between quantitative measures obtained with FBM, clinical parameters acquired from the patients, caries detection, and assessment of activity status in occlusal surfaces of primary molars.

DESIGN

Six hundred and six teeth from 113 children (4-14 years) were evaluated. The presence of a biofilm, caries experience, and the number of active lesions were recorded. The teeth were assessed using FBM: DIAGNOdent pen (Lfpen) and Quantitative light-induced fluorescence (QLF). As reference standard, all teeth were evaluated using the ICDAS (International Caries Detection and Assessment System) associated with clinical activity assessments. Multilevel regressions compared the FBM values and evaluated the association between the FBM measures and clinical variables related to the caries activity.

RESULTS

The measures from the FBM were higher in cavitated lesions. Only, ∆F values distinguished active and inactive lesions. The LFpen measures were higher in active lesions, at the cavitated threshold (56.95 ± 29.60). Following regression analyses, only the presence of visible biofilm on occlusal surfaces (adjusted prevalence ratio = 1.43) and ∆R values of the teeth (adjusted prevalence ratio = 1.02) were associated with caries activity.

CONCLUSION

Some quantitative measures from FBM parameters are associated with caries activity evaluation, which is similar to the clinical evaluation of the presence of visible biofilm.

Comparison of quantitative light-induced fluorescence, digital photography and transverse microradiography for quantification of enamel remineralization

BACKGROUND

Quantitative light-induced fluorescence (QLF) and digital photography (DP) have been proposed as clinical methods for measuring changes in enamel mineral content. The aim of this study was to compare the ability of QLF and DP with the in vitro gold standard transverse microradiography (TMR) to measure the remineralization of enamel subsurface lesions.

METHODS

Subsurface lesions were formed in enamel (n = 40) and exposed to remineralization solutions for 10 days. Changes were analysed by DP, QLF and TMR to determine percentage changes in luminescence (%L), fluorescence (%F) and mineral content (%R), respectively and correlation between these parameters determined.

RESULTS

The correlations between TMR and QLF (r = 0.63), TMR and DP (r = 0.59), and DP and QLF (r = 0.64) were all moderate but statistically significant (p < 0.001). The variability in %L and, to a lesser extent, %F values significantly impacted on the potential role of DP and QLF as methods by which mineral content changes produced by remineralization treatments could be accurately measured.

CONCLUSIONS

Both QLF and DP provided data that correlated moderately with TMR data. QLF images were easier to analyse, free of glare and had less variability compared with those produced using DP.

Use of ICDAS combined with quantitative light-induced fluorescence as a caries detection method

The purpose of this study was to combine a standardized visually based system, the International Caries Detection and Assessment System (ICDAS), with a sensitive fluorescence-based system, quantitative light-induced fluorescence (QLF), to determine the ability to monitor caries lesion progression. This combination (QLF-I) has the potential to increase the sensitivity of the visual method without compromising specificity. A total of 460 children were enrolled and examined at baseline, 8 months and 12 months by ICDAS and QLF by a single examiner. The examiner repeatability for both methods was comparable, varying between weighted kappa of 0.70 and 0.79. The DMFT score was 6.0 (SD 5.8) at baseline and 6.4 (SD 6.3) at 12 months, and both methods were able to follow the increase in incidence. The QLF-I scored more surfaces at the early ICDAS scores (1 and 2) and score 4. Not all lesions progressed at the same rate, differing by score at baseline and surface type.

Effect of a xylitol and fluoride containing toothpaste on the remineralization of human enamel in vitro

The aim of this study was to examine the effect of a fluoride and xylitol containing toothpaste on the remineralization of human enamel using Quantitative Light-induced Fluorescence (QLF). Human extracted teeth were cut longitudinally into three or four parts, and artificial subsurface lesion windows (2 mm x 3 mm) were created by immersion in demineralizing solution. Each enamel sample (n = 7) was treated for 3 min at 25 degrees C twice a day for consecutive 14 days with the slurry of a silica-based toothpaste 1) without F- and xylitol (blank), 2) with 500 ppm F- and 3) with 500 ppm F- and 5% xylitol toothpaste. In addition, we measured the remineralization ability of a commercially available toothpaste 4) with 500 ppm F-. The average fluorescence loss F (%) and lesion size (mm2) were determined with QLF. Another variable, delta Q, which was defined as the fluorescence loss integrated over the lesion size (%, mm2), was calculated. The results showed that the combination of 500 ppm F- and 5% xylitol toothpaste significantly (P < 0.05) recovered both the size and delta Q compared to the other groups. These findings suggested that inclusion of xylitol in fluoride toothpaste might be useful to enhance the remineralization in vivo.

Assessment of Autofluorescence to Detect the Remineralization Capabilities of Sodium Fluoride, Monofluorophosphate and Non-Fluoride Dentifrices

The purpose of the study was to determine if longitudinal measurements of enamel autofluorescence (quantitative light-induced fluorescence, QLF) could detect differences in remineralization of early enamel caries on buccal surfaces of anterior teeth following supervised daily brushing with either sodium fluoride (NaF; 1,450 ppm F), sodium monofluorophosphate (MFP; 1,450 ppm F) dentifrices or a herbal, non-fluoride placebo dentifrice. The study was a pragmatic cluster-randomized controlled trial with schools as the unit of randomization. Twenty-one schools in Chengdu, China, comprised the clusters; 296 children with at least 1 visible white-spot lesion were examined using QLF at baseline and after 3 and 6 months. Each of the 21 clusters was randomly assigned 1 of the 3 dentifrices, and the children brushed under supervision once per day for 2 min. The primary outcome measure was deltaQ (product of fluorescence loss and area) at a 5% threshold after 6 months of product use. A multi-level model was fitted to the data at the site level, taking into account the hierarchical structure with baseline deltaQ, age and sex as covariates. After 3 months there was a significant difference between the MFP group and placebo (p = 0.02) and after 6 months between the NaF group (p = 0.002), MFP group (p < 0.001) and the placebo. QLF methodology could detect, within 3- and 6-month periods of supervised brushing, a difference in remineralization between fluoride-containing and non-fluoride-containing dentifrices. Typically lesions in all 3 treatment groups demonstrated improvement. Groups receiving fluoride experienced a more rapid and more substantial remineralization than those in the placebo group.

The effect of video repositioning on the reliability of light-induced fluorescence imaging: an in vivo study

The ability to monitor longitudinally the development, arrest or resolution of early demineralised lesions is one strength of quantitative light-induced fluorescence (QLF). When taking sequential images of an individual's teeth for monitoring it has been suggested that the subsequent images should be taken from the same position the baseline image. To assist in this process, video repositioning software is available that enables automatic capture of images once the system identifies that they are similar enough to the baseline comparator. The purpose of this study was to determine if the use of such software-assisted capture improves the reliability of subsequent QLF analysis. 20 subjects had 34 surfaces (buccal and occlusal) imaged by 2 examiners at baseline, and again 1 week later using both manual and software-assisted (VidRep) systems. Analysis of the three key reportable values for QLF (DeltaF, lesion area, DeltaQ) suggested that there is no significant improvement in reliability using VidRep although VidRep demonstrates additional advantages above and beyond image geometry, relating to the speed of subsequent image analysis.