Quantitative Light-induced Fluorescence Analysis Research Articles

Assessment of the Caries Detection Ability of Quantitative Light-induced Fluorescence (QLF) in Primary Teeth <italic>in vitro</italic>

The aim of this study was to evaluate QLF (quantitative light-induced fluorescence) technology for the caries detection in primary teeth and validate the relationships between the cavity volume of carious lesions and QLF analysis results. Total 125 tooth surfaces include 53 occlusal surfaces, and 72 proximal surfaces were investigated with the portable QLF device for detection of dental caries in primary molars. Micro-CT radiograph was also performed to classify carious lesions and calculate the cavity volume. QLF showed good accuracy and reliability (sensitivity 0.75 - 0.94, specificity 0.82 - 0.95, and AUROC 0.88 - 0.98) for the caries detection in primary teeth except ΔR average results of proximal caries which showed relatively low values. Statistically significant relationships were found between ΔF average, QS-Index and the cavity volume according to Spearman rank-order correlation coefficients (r = 0.805 - 0.832, p < 0.001). QLF detection method would be a harmless and reliable way for children to diagnose dental caries without the concern about radiation exposure.

Characterization of white spot lesions formed on human enamel under microcosm biofilm for different experimental periods.

The initial characteristics of white spot lesion (WSLs), such as the degree of integrated mineral loss (ΔZ), depth and pattern of mineral distribution, have an impact on further demineralization and remineralization. However, these lesion parameters have not been evaluated in WSLs produced from microcosm biofilms.Objective:This study characterized artificial white spot lesions produced on human enamel under microcosm biofilm for different experimental periods.Methodology:In total, 100 human enamel specimens (4x4mm) were assigned to 5 distinct groups (n=20/group) differing according to the period of biofilm formation (2, 4, 6, 8 or 10 days). Microcosm biofilm was produced on the specimens from a mixture of human and McBain saliva at the first 8h. Enamel samples were then exposed to McBain saliva containing 0.2% sucrose. WSLs formed were characterized by quantitative light-induced fluorescence (QLF) and transverse microradiography (TMR). Data were analyzed by ANOVA/Tukey or Kruskal-Wallis/Dunn tests (p<0.05).Results:A clear time-response pattern was observed for both analyses, but TMR was able to better discriminate among the lesions. Regarding QLF analysis, median (95%CI; %) changes in fluorescence ∆Z were -7.74(-7.74:-6.45)a, -8.52(-8.75:-8.00)ab, -9.17(-10.00:-8.71)bc, -9.58(-10.53:-8.99)bc and -10.01(-11.44:-9.72)c for 2, 4, 6, 8, and 10 days, respectively. For TMR, median (95%CI; vol%.µm) ∆Z were 1410(1299-1479)a, 2420(2327-2604)ab, 2775(2573-2899)bc, 3305(3192-3406)cd and 4330(3972-4465)d, whereas mean (SD; µm) lesion depth were 53.7(12.3)a, 71.4(12.0)a, 103.8(24.8)b, 130.5(27.2)bc, 167.2(39.3)c for 2, 4, 6, 8 and 10 days, respectively.Conclusion:The progression of WSLs formed on human enamel under microcosm biofilm can be characterized over 2-10 days, both by QLF and TMR analyses, although the latter provides better discrimination among the lesions.

Ecological changes in oral microcosm biofilm during maturation.

The aim of this study was to evaluate the ecological changes in the biofilm at different stages of maturation using 16S rDNA gene amplicon sequencing and to identify correlations between red/green (R/G) fluorescence ratio and ecological changes. An oral microcosm biofilm was initiated from the saliva of a single donor and grown anaerobically for up to 10 days in basal medium mucin. Quantitative light-induced fluorescence analysis was shown that the R/G ratio of the biofilm increased consistently, but the slope rapidly decreased after six days. The bacterial compositions of 10 species also consistently changed over time. However, there was no significant correlation between each bacteria and red fluorescence. The monitoring of the maturation process of oral microcosm biofilm over 10 days revealed that the R/G ratio and the bacterial composition within biofilm consistently changed. Therefore, the R/G fluorescence ratio of biofilm may be related with its ecological change rather than specific bacteria

Evaluation of Degradation in Nanofilled Adhesive Resins Using Quantitative Light‐Induced Fluorescence

The aim of this study was to evaluate degradation in commercial dental nanofilled adhesive resins using quantitative light‐induced fluorescence (QLF). Three adhesives were selected: D/E resin (DR), Single Bond Plus (SB), and G‐Bond (GB). The adhesives were mixed with porphyrin for the QLF analysis. Specimens were prepared by dispensing blended adhesives into a flexible mold and polymerizing. Then, the QLF analysis of the specimens was done and the porphyrin values (Simple Plaque Score and ΔR) were measured. After thermocycling of the specimens (5000 cycles, 5 to 55°C) for the degradation, the specimens were assayed by QLF again. The porphyrin values were analyzed using paired t‐test at a 95% confidence level. A significant reduction in SPS was observed in all groups after thermocycling. The ΔR significantly decreased after thermocycling except area ΔR30 of SB group. Overall, porphyrin values decreased after thermocycling which indicates that the degradation of the adhesive resins may be measured by the change of porphyrin value. The QLF method could be used to evaluate the degradation of adhesive resin.

The effect of pH and fluoride concentration of liquid dentifrices on caries progression

This randomized clinical trial evaluated the effect of pH and fluoride concentration of liquid dentifrices (LD) on caries progression and fluoride uptake in the toenails of 2-4-year-old children. Schoolchildren living in a fluoridated area, with (A) or without (I) active caries lesions, were randomly allocated into three groups according to the LD they would use over 12 months: group 1 (n = 48-A/56-I): 550 μg fluoride (F)/g, pH 4.5; group 2 (n = 56-A/48-I) 1,100 μg F/g, pH 7.0; and group 3 (n = 52-A/55-I): 550 μg F/g, pH 7.0. The number of lesions becoming active/cavities or inactive was clinically evaluated by determining progression or regression. Additionally, white spot lesions were evaluated by the quantitative light-induced fluorescence (QLF) method in 75 children. Toenail fluoride concentration was also evaluated. Data were analyzed by ANOVA and followed by Dunn's test or ANCOVA followed by Tukey's test (p < 0.05). Caries net increment followed a decreasing pattern according to the dentifrice used (G1 < G2 < G3), regardless caries activity, but significant differences were detected only for caries progression and net increment (G1 < G3) for the caries-active group when evaluated through visual inspection. For the regression, the values found for the three groups were more similar, without significant differences. QLF analysis detected no significant difference between groups 1 and 2, but they performed significantly better than group 3. A significantly lower toenail fluoride concentration was observed when children used the low-fluoride dentifrices. The low-fluoride acidic LD has good potential to prevent caries and reduce fluoride intake. The low-F acidic dentifrice combines the desirable characteristics of caries prevention and reduced fluoride intake-for a product to be used by children, regardless their caries status.

Quantitative light-induced fluorescence (QLF): A tool for early occlusal dental caries detection and supporting decision making in vivo

ObjectivesThis study reports the development and assessment of a novel method using quantitative light-induced fluorescence (QLF), to determine whether QLF parameters ΔF and ΔQ were appropriate for aiding diagnosis and clinical decision making of early occlusal mineral loss by comparing QLF analysis with actual restorative management. MethodsFollowing ethical approval, 46 subjects attending a dental teaching hospital were enrolled. White light digital (WL) and QLF images/analyses of 46 unrestored posterior teeth with suspected occlusal caries were made after a clinical decision had already been taken to explore fissures operatively. WL and QLF imaging/analysis were repeated after initial cavity preparation. The type of restorative treatment was determined by the supervising clinician independent of any imaging performed. Actual restorative management carried out was recorded as fissure sealant/preventive resin restoration (F/P) or class I occlusal restoration (Rest.) thus reflecting the extent of intervention (=gold standard). All QLF images were analysed independently. ResultsThe results showed statistically significant differences between the two treatment groups ΔF (p=0.002) (mean 22.60 – F/P and 28.80 – Rest.) and ΔQ (p=0.012) (mean 230.49 – F/P and 348.30 – Rest.). ConclusionsΔF and ΔQ values may be useful in aiding clinical diagnosis and decision making in relation to the management of early mineral loss and restorative intervention of occlusal caries. Clinical significanceQLF has the potential to be a valuable tool for caries diagnosis in clinical practice.

The evaluation of a novel method comparing quantitative light-induced fluorescence (QLF) with spectrophotometry to assess staining and bleaching of teeth

This study reports the development and evaluation of a novel method using quantitative light-induced fluorescence (QLF), which enables its use for quantifying and assessing whole tooth surface staining and tooth whitening. The method was compared with a spectrophotometer to assess reliability. Two experimental phases, intrinsic stain formation and tooth whitening, were conducted in vitro on 16 extracted bovine teeth. Intrinsic stains were developed via access through lingual surfaces and root canals of these teeth using tea solution (2 g/100 ml, Marks and Spencer Extra Strong Tea, Marks and Spencer, London, UK) for 6 days. Stains were removed using 33% hydrogen peroxide (VWR Prolab, Leicestershire, UK) in cycles over 150 min. Stain development/whitening was monitored with QLF (Inspektor Research systems, Amsterdam, Netherlands) and spectrophotometry (Easy shade, Vita Zahnfabrik, Bad Säckingen, Germany). Parameters Delta F for QLF and Delta E for the spectrophotometer were obtained. The progression of stain intensity and removal observed by the methods were tested for correlation using Pearson's correlation coefficient. Intra-examiner reliability for each method was tested. QLF showed a high correlation with spectrophotometry for detecting and monitoring intrinsic tooth stain progression (Pearson coefficient r was -0.987 with correlation significant p < 0.0001). For stain removal, the Pearson coefficient (r) between both methods was -0.906 with no significance p = 0.094. The use of an external reference material in combination with the inner patch QLF analysis technique had the ability to detect and measure whole tooth surface staining and its removal longitudinally. The reliability of the method shows a potential clinical application.

Caries lesions after orthodontic treatment followed by quantitative light-induced fluorescence: a 2-year follow-up

The aim of this study was to monitor, by means of quantitative light-induced fluorescence (QLF), the natural behaviour of white spot lesions detected immediately after orthodontic treatment and 2 years post-treatment. The buccal tooth surfaces of 51 subjects (>or=12 years), 24 males and 27 females, were examined with QLF for the presence of caries immediately after debonding (T0), and 6 weeks (T1), 6 months (T2), and 2 years (T3) thereafter. The fluorescence loss [Delta F (per cent)] and area [A (mm(2))] of any lesions were determined using dedicated software. The lesion development and influence of gender were determined by a general linear model (Friedman repeated-measures analysis and two-way repeated-measures analysis of variance). Using QLF, 370 carious surfaces were recorded at T0. During the study, 19 lesions were lost from QLF analysis of which 16 lesions (Delta F(0)=7.6-39.2 per cent) in two subjects were restored and three teeth with lesions were extracted or crowned. This resulted in 351 lesions that were included in this study with a median Delta F at T0 of 8.5 per cent (quartiles 6.6 per cent; 11.9 per cent). The lesions varied from incipient (Delta F<10 per cent, n=227) to advanced (Delta F>25 per cent, n=6). Overall, the lesions showed improvement between T0 and T2 (P<0.01) but no further significant improvement at T3. Thirty-five lesions became significantly worse after 2 years. The majority of lesions (n=171) were considered to be stable, and 145 lesions improved significantly of which only 10 lesions improved to such an extent that they disappeared. White spot lesions developed during orthodontic treatment have very limited ability to improve after appliance removal. Further research to investigate the potential of preventive measures to enhance lesion improvement is necessary.

Longitudinal development of caries lesions after orthodontic treatment evaluated by quantitative light-induced fluorescence

The aim of this investigation was to use quantitative light-induced fluorescence to study the natural behavior of white-spot lesions that developed in orthodontic patients during treatment with fixed orthodontic appliances, after the removal of those appliances. The sample comprised 58 consecutively recruited patients who were at least 12 years old and who had been treated with a fixed appliance for at least 1 year in the department of orthodontics at the Academic Center for Dentistry Amsterdam, The Netherlands. They were examined with quantitative light-induced fluorescence for the presence and the extent of caries on the buccal surfaces of their teeth directly after debonding and 6 weeks and 6 months later. The fluorescence loss (DeltaF [%]) and area of lesions (mm2) were determined for all lesions found. A total of 421 carious lesions were recorded at debracketing with an average fluorescence loss (DeltaF(0)) of 10.3% (SD, 5.4%). During the study, 15 lesions were lost from quantitative light-induced fluorescence analysis: 11 lesions (DeltaF(MAX,0) >25%) in 2 subjects were restored, and 4 were not analyzed because they were not imaged properly. Lesions varied from incipient, ie, white spot (DeltaF(0) <10%, n = 257), to advanced, ie, dentinal (DeltaF(0) >25%, n = 12). A small lesion improvement was seen 6 weeks after debracketing (P <.01), and a further lesion improvement was seen after 6 months (P <.01). Incipient lesions on average showed a smaller improvement (relative decrease, 2%; SD, 20%) than lesions with DeltaF(0) >10% (relative decrease, 12%; SD, 20%; P <.01). The lesions that developed during orthodontic treatment improved once the fixed appliances were removed even when they were advanced, but the overall regression was small.

The Microbiological Origin of Fluorescence Observed in Plaque on Dentures during QLF Analysis

The aim of this study was to determine the microbiological origin of plaque fluorescence observed during quantitative light-induced fluorescence (QLF) analysis. Plaque was sampled from dentures, because of easy accessibility and the homogeneous background provided by the denture tooth during imaging, and the acknowledged comparability to occlusal plaque. Forty removable poly(methyl methacrylate) dentures were screened for the presence of fluorescent plaque deposits during QLF analysis. Dentures were photographed, QLF images were recorded and samples of fluorescent plaque were taken. Plaque samples were cultured on fastidious anaerobe agar, Wilkins Chalgren agar and Sabourauds dextrose agar. Plates were screened under QLF and fluorescent colonies were subcultured and identified. Areas of red, orange and green fluorescence were detected on the fitting and non-fitting surfaces of dentures. The red and orange fluorescing species were Prevotella melaninogenica, Actinomyces israelii and Candida albicans, which are generally acknowledged to be secondary colonisers, present in more mature plaque. Green fluorescence was observed in streptococcal species (early colonisers) and Fusobacterium nucleatum (important organism in plaque development). Non-fluorescent colonies were also cultured. Plaque which accumulates on susceptible surfaces tends to be associated with caries, but it may be its maturity, rather than the presence of cariogenic streptococci, that is more likely to provide a microbiological link between red fluorescence and caries.

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 (ΔF, lesion area, ΔQ) 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.

The intra- and inter-examiner reliability of quantitative light-induced fluorescence (QLF) analyses

Objective To assess the reliability of the analysis stage of quantitative light-induced fluorescence (QLF). The QLF analysis involves subjective input from the user and this study examines the influence of this on the reproducibility of the QLF data. Method QLF images were taken of 20 human molar teeth that had been previously subjected to a demineralising solution (phosphoric acid 37%) to create artificial white spot lesions on their buccal surfaces. Following examination of the images, 16 were chosen to represent a range of lesion size and severity. Three copies were made of the images and each was allocated a different filename. 10 examiners in three centres were asked to analyse each of the 16 images on three occasions, with at least seven days between each attempt. Simple instructions describing the analysis procedure were supplied and examiners were asked to adhere to these directions. Examiners were asked to rate each of the 16 teeth on their first attempt both quantitatively (5 point scale) and qualitatively in terms of difficulty of analysis. Data reported were the ΔQ at 5% threshold for each tooth on each of three attempts. Results Using ANOVA and paired t-tests to detect statistical differences, the three attempts of each examiner were used to determine intra-examiner reliability. Only one examiner (a novice at the technique) demonstrated differences between all three attempts and two demonstrated difference between one attempt. When the mean scores were compared to determine the inter-examiner reliability, only one examiner's results were statistically different when compared with two others. Conclusion This study has demonstrated that the analysis stage of QLF is reliable between examiners and within multiple attempts by the same examiner, when analysing in vitro lesions. Novices at the technique should be trained before analysing experimental data.

Is the analysis of a QLF measurement reliable and reproducible?

Objective To assess the reliability of the analysis stage of quantitative light-induced fluorescence (QLF). The QLF analysis involves subjective input from the user and this study examines the influence of this on the reproducibility of the QLF data. Method QLF images were taken of 20 human molar teeth that had been previously subjected to a demineralising solution (phosphoric acid 37%) to create artificial white spot lesions on their buccal surfaces. Following examination of the images, 16 were chosen to represent a range of lesion size and severity. Three copies were made of the images and each was allocated a different filename. 10 examiners in three centres were asked to analyse each of the 16 images on three occasions, with at least seven days between each attempt. Simple instructions describing the analysis procedure were supplied and examiners asked to adhere to these directions. Examiners were asked to rate each of the 16 teeth on their first attempt both quantitatively (5 point scale) and qualitatively in terms of difficulty of analysis. Data reported were the δQ at 5% threshold for each tooth on each of three attempts. Results Using ANOVA and paired t-tests to detect statistical differences, the three attempts of each examiner were used to determine intra-examiner reliability. Only one examiner (a novice at the technique) demonstrated differences between all three attempts and two demonstrated difference between one attempt. When the mean scores were compared to determine the inter-examiner reliability, only one examiner's results were statistically different when compared with two others. Conclusion This study has demonstrated that the analysis stage of QLF is reliable between examiners and within multiple attempts by the same examiner, when analysing in vitro lesions. Novices at the technique should be trained before analysing experimental data.

The intra- and inter-examiner reliability of quantitative light-induced fluorescence (QLF) analyses.

To assess the reliability of the analysis stage of quantitative light-induced fluorescence (QLF). The QLF analysis involves subjective input from the user and this study examines the influence of this on the reproducibility of the QLF data. QLF images were taken of 20 human molar teeth that had been previously subjected to a demineralizing solution (phosphoric acid 37%) to create artificial white spot lesions on their buccal surfaces. Following examination of the images, 16 were chosen to represent a range of lesion size and severity. Three copies were made of the images and each was allocated a different filename. 10 examiners in three centres were asked to analyse each of the 16 images on three occasions, with at least seven days between each attempt. Simple instructions describing the analysis procedure were supplied and examiners were asked to adhere to these directions. Examiners were asked to rate each of the 16 teeth on their first attempt both quantitatively (5 point scale) and qualitatively in terms of difficulty of analysis. Data reported were the delta Q at 5% threshold for each tooth on each of three attempts. Using ANOVA and paired t-tests to detect statistical differences, the three attempts of each examiner were used to determine intra-examiner reliability. Only one examiner (a novice at the technique) demonstrated differences between all three attempts and two demonstrated difference between one attempt. When the mean scores were compared to determine the inter-examiner reliability, only one examiner's results were statistically different when compared with two others. This study has demonstrated that the analysis stage of QLF is reliable between examiners and within multiple attempts by the same examiner, when analysing in vitro lesions. Novices at the technique should be trained before analysing experimental data.