Baek-Il Kim

Association between the cariogenicity of a dental microcosm biofilm and its red fluorescence detected by Quantitative Light-induced Fluorescence-Digital (QLF-D)

OBJECTIVE This study evaluated whether Quantitative Light-induced Fluorescence-Digital (QLF-D) can detect the levels of cariogenicity of dental microcosm biofilms by assessing the red fluorescence intensity. METHODS Dental microcosm biofilms were initiated from human saliva on bovine enamel discs. Biofilms with various levels of cariogenicity were then grown in artificial saliva supplemented with sucrose at different concentrations (0.05%, 0.1%, 0.2%, and 0.5%) in 24-well microplates. After 10 days, fluorescence images of the biofilms were captured by the QLF-D to analyse the red fluorescence intensity, which was quantified as the red/green ratio (R/G value). The supernatant pH was also measured, as well as the total and aciduric bacteria counts of the collected biofilms. Mineral loss in enamel was also evaluated by calculating the percentage of surface microhardness changes (%SHC). RESULTS The R/G values of the biofilms differed significantly with the sucrose concentration (p<0.0001), increasing consistently as the sucrose concentration increased from 0.05% (=0.91) to 0.5% (=2.56). Strong correlation was identified between the R/G value and the number of aciduric bacteria (r=0.83, p<0.0001), supernatant pH (r=-0.95, p<0.0001), and %SHC (r=0.90, p<0.0001). CONCLUSIONS The red fluorescence as observed by the QLF-D was correlated with the cariogenic properties of dental microcosm biofilms in vitro, which indicates that this device can be used to detect the levels of cariogenicity of a dental biofilm. CLINICAL SIGNIFICANCE The QLF-D is able to assess the cariogenic levels of dental plaque based on the intensity of red fluorescence.

Monitoring the maturation process of a dental microcosm biofilm using the Quantitative Light-induced Fluorescence-Digital (QLF-D)

OBJECTIVE The aim of this study was to investigate whether Quantitative Light-induced Fluorescence-Digital (QLF-D) could monitor the degree of maturation of dental microcosm biofilms by observing the red fluorescence emitted from the biofilms. METHODS Dental microcosm the biofilms were grown on bovine enamel discs. They were initiated from human saliva, and then grown in 0.5% sucrose growth media for 10 days. On days 1, 2, 3, 7, and 10 after the inoculation, fluorescence images of the biofilms were captured using the QLF-D and the red fluorescence intensity was quantified by calculating the red/green ratio (R/G value). Total and aciduric bacteria within the biofilms were counted, and the degree of demineralization was evaluated by measuring the percentage of surface microhardness change (ΔVHN) and lesion depth in the enamel. RESULTS The R/G values of the biofilms assessed by the QLF-D increased significantly over time up to 7 days after inoculation (p<0.0001). The R/G values showed significant positive correlations with the total bacterial CFUs (r=0.74, p=0.001), aciduric bacterial CFUs (r=0.85, p=0.001), ΔVHN (r=0.65, p=0.001), and lesion depth in the enamel (r=0.82, p=0.001) according to the maturation time. CONCLUSIONS The red fluorescence detected by the QLF-D increased according to biofilm maturation and was significantly associated with the cariogenicity of the biofilm. Therefore, this device could be used to monitor the degree of biofilm maturation by observing the red fluorescence emitted from cariogenic biofilms. CLINICAL SIGNIFICANCE The QLF-D enables the detection of a mature dental plaque and monitoring of its cariogenic status by observing the plaque fluorescence non-destructively, in real time.

Panel of candidate biomarkers for renal cell carcinoma

The timely diagnosis and therapeutic monitoring of human renal cell carcinoma (RCC) is limited by the lack of specific biomarkers. To identify candidate RCC biomarkers, we used 2-DE gel electrophoresis with mass spectrometry and 2-DE spot intensity-based ROC analysis to analyze 18 sets of paired normal and RCC tumor tissue including conventional, papillary, and chromophobe subtypes. Validation was performed with RCC patient plasma samples and confirmed by clustergram, shRNA, and immunohistochemistry assays. Cardinal candidates were evaluated by ELISA. The leading candidate biomarker that was upregulated in RCC samples according to the clustergram and validation analysis was nicotinamide N-methyltransferase (NNMT) (13/15, P < 0.0001). Other upregulated candidate biomarkers that were identified by this method include ferritin, hNSE, NM23, secretagogin, and L-plastin. The upregulation of NNMT in RCC was confirmed by immunoblotting and immunohistochemistry. Analysis of fractionated membrane-associated proteins identified CAP-G, mitofillin, tubulin alpha, RBBP7, and HSP27. Of these, RBBP7 and HSP27 were highly expressed in the chromophobe subtype of RCC (3/3) but were absent from conventional RCC (0/3). The triple combination of the NNMT, FTL, and hNSE biomarkers had the highest predictive capacity of 0.993, while NNMT was the single, most powerful candidate diagnostic biomarker for all types of RCC.

Antibacterial characteristics of Curcuma xanthorrhiza extract on Streptococcus mutans biofilm.

This study evaluated the antibacterial effects of a natural Curcuma xanthorrhiza extract (Xan) on a Streptococcus mutans biofilm by examining the bactericidal activity, inhibition of acidogenesis and morphological alteration. Xan was obtained from the roots of a medicinal plant in Indonesia, which has shown selective antibacterial effects on planktonic S. mutans. S. mutans biofilms were formed on slide glass over a 72 h period and treated with the following compounds for 5, 30, and 60 min: saline, 1% DMSO, 2 mg/ml chlorhexidine (CHX), and 0.1 mg/ml Xan. The Xan group exposed for 5 and 30 min showed significantly fewer colony forming units (CFU, 57.6 and 97.3%, respectively) than those exposed to 1% DMSO, the negative control group (P<0.05). These CFU were similar in number to those slides exposed to CHX, the positive control group. Xan showed similar bactericidal effect to that of CHX but the dose of Xan was one twentieth that of CHX. In addition, the biofilms treated with Xan and CHX maintained a neutral pH for 4 h, which indicates that Xan and CHX inhibit acid production. Scanning electron microscopy showed morphological changes in the cell wall and membrane of the Xan-treated biofilms; an uneven surface and a deformation in contour. Overall, natural Xan has strong bactericidal activity, inhibitory effects on acidogenesis, and alters the microstructure of S. mutans biofilm. In conclusion, Xan has potential in anti-S. mutans therapy for the prevention of dental caries.

Validation of quantitative light-induced fluorescence-digital (QLF-D) for the detection of approximal caries in vitro

OBJECTIVES Detection of approximal caries lesions can be difficult due to their anatomical position. This study aimed to assess the ability of the quantitative light-induced fluorescence-digital (QLF-D) in detecting approximal caries, and to compare the performance with those of the International Caries Detection and Assessment System II (ICDAS II) and digital radiography (DR). METHODS Extracted permanent teeth (n=100) were selected and mounted in pairs. The simulation pairs were assessed by one calibrated dentist using each detection method. After all the examinations, the teeth (n=95) were sectioned and examined histologically as gold standard. The modalities were compared in terms of sensitivity, specificity, areas under receiver operating characteristic curves (AUROC) for enamel (D1) and dentine (D3) levels. The intra-examiner reliability was assessed for all modalities. RESULTS At D1 threshold, the ICDAS II presented the highest sensitivity (0.80) while the DR showed the highest specificity (0.89); however, the methods with the greatest AUC values at D1 threshold were DR and QLF-D (0.80 and 0.80 respectively). At D3 threshold, the methods with the highest sensitivity were ICDAS II and QLF-D (0.64 and 0.64 respectively) while the method with the lowest sensitivity was DR (0.50). However, with regard to the AUC values at D3 threshold, the QLF-D presented the highest value (0.76). All modalities showed to have excellent intra-examiner reliability. CONCLUSIONS The newly developed QLF-D was not only able to detect proximal caries, but also showed to have comparable performance to the visual inspection and radiography in detecting proximal caries. CLINICAL SIGNIFICANCE QLF-D has the potential to be a useful detection method for proximal caries.

Assessing the use of Quantitative Light-induced Fluorescence-Digital as a clinical plaque assessment

BACKGROUND The aims of this study were to compare the relationship between red fluorescent plaque (RF plaque) area by Quantitative Light-induced Fluorescence-Digital (QLF-D) and disclosed plaque area by two-tone disclosure, and to assess the bacterial composition of the RF plaque by real time-PCR. METHODS Fifty healthy subjects were included and 600 facial surfaces of their anterior teeth were examined. QLF-D was taken on two separate occasions (before and after disclosing), and the RF plaque area was calculated based on Plaque Percent Index (PPI). After disclosing, the stained plaque area was analyzed to investigate the relationship with the RF plaque area. The relationship was evaluated using Pearson correlation and paired t-test. Then, the RF and non-red fluorescent (non-RF) plaque samples were obtained from the same subject for real-time PCR test. Total 10 plaque samples were compared the ratio of the 6 of bacteria using Wilcoxon signed rank test. RESULTS Regarding the paired t-test, the blue-staining plaque area (9.3±9.2) showed significantly similarity with the RF plaque area (9.1±14.9, p=0.80) at ΔR20, however, the red-staining plaque area (31.6±20.9) presented difference from the RF plaque area (p<0.0001). In addition, bacterial composition of Prevotella intermedia and Streptococcus anginosus was associated with substantially more the RF plaque than the non-RF plaque (p<0.05). CONCLUSIONS The plaque assessment method using QLF-D has potential to detect mature plaque, and the plaque area was associated with the blue-staining area using two-tone disclosure.

Validity and reliability of autofluorescence-based quantification method of dental plaque.

BACKGROUND The aim of this study was to evaluate validity and reliability of autofluorescence-based plaque quantification (APQ) method. METHODS The facial surfaces of 600 sound anterior teeth of 50 subjects were examined. The subjects received dental plaque examination using Turesky modified Quigley Hein plaque index (QHI) and Silness & Löe plaque index (SLI). The autofluorescence images were taken before the plaque examination with Quantitative Light-induced Fluorescence-Digital, and plaque percent index (PPI) was calculated. Correlation between two existing plaque indices and the PPI of the APQ method was evaluated to find which level of plaque redness on tooth (ΔR) by the APQ method shows the highest correlation. The area under the ROC curve (AUC) analysis and intra- and inter-examiner reliability tests were performed. RESULTS The PPIΔR20 of the APQ method showed a moderate correlation with two existing plaque indices (rho of QHI=0.48, SLI=0.51). This methodology fell in the fair category and it had an excellent reliability. The APQ method also showed possibility to detect heavy plaque with fair validity. CONCLUSIONS The APQ method demonstrated excellent reliability, and fair validity, compared with 2 conventional indices. The plaque quantification described has the potential to be used in clinical evaluation of oral hygiene procedures.

Validity of Screening Methods for Periodontitis Using Salivary Hemoglobin Level and Self-Report Questionnaires in People with Disabilities

BACKGROUND The aim of this study is to evaluate the validity of screening methods in predicting periodontitis in people with disabilities using the objective salivary hemoglobin level, a subjective self-report questionnaire, and a combined model of the two methods with demographic characteristics. METHODS The participants were 195 patients with disabilities aged >18 years who were examined using the community periodontal index (CPI), salivary hemoglobin level, and answers to 10 self-report questions (n = 192). Multivariable logistic regression and receiver operating characteristic (ROC) curve analysis were performed to evaluate the validity of the methods and the combined model in predicting the prevalence of ≥CPI 3 (probing depth [PD] ≥4 mm) or CPI 4 (PD ≥6 mm). RESULTS Overall, 75.9% of the study group (148 of 195) were diagnosed with ≥CPI 3, and 38.5% of the study group (75 of 195) were diagnosed with CPI 4. The areas under the ROC curve (AUCs) of the salivary hemoglobin level were 0.578 (sensitivity of 41% and specificity of 77%) and 0.662 (sensitivity of 53% and specificity of 75%) for predicting the prevalence of ≥CPI 3 and CPI 4, respectively. Multivariable modeling incorporating four different questions for predicting ≥CPI 3 or CPI 4 indicated higher AUCs of 0.710 and 0.732, respectively, yielding higher sensitivity (55% for ≥CPI 3 and 69% for CPI 4) than that of salivary hemoglobin level. The most useful prediction models for ≥CPI 3 or CPI 4 were combined models, which yielded AUCs of 0.773 and 0.807, respectively, with sensitivity values of 70% and specificity values >75%. CONCLUSION The salivary hemoglobin level, self-report questionnaire, and the combined method demonstrated screening potential that could predict the population prevalence of ≥CPI 3 or CPI 4.

Modification of surface pre-treatment for resin infiltration to mask natural white spot lesions.

OBJECTIVES The aims of this study were to investigate an alternative pre-treatment method for resin infiltration using 37% H3PO4 with a brush applicator and to evaluate the penetration effect of the infiltrant for masking the natural white spot lesions (WSLs) in human teeth. METHODS Seventy extracted human molars and pre-molars with non-cavitated WSLs were collected. Thirty teeth met criteria of ICDAS code 2, and were sectioned, providing a total of sixty paired halves. For the control group, 15% HCl gel was applied for 120s, and 37% H3PO4, gel was gently rubbed with a brush applicator for 30s to the experimental group. Also, to evaluate the penetration effect of the infiltrant by pre-treatment, the specimens were treated with the infiltrant (Icon®). Thicknesses of the removed surfaces and percentages of the infiltrated areas (IA%) were evaluated by CLSM, and micro-morphological changes were observed by SEM. RESULTS The mean thicknesses of removed surface layers were significantly different between the control group (36±7.62μm) and the experimental group (13±2.76μm) (p<0.001). But, the means of IA% were similar in both groups (p>0.05). In the SEM images, the prism cores were preferentially dissolved in the control group, while the prism peripheries were preferentially dissolved in the experimental group. CONCLUSIONS Applying 37% H3PO4 gel with an applicator brush for 30s could increase the permeability and minimize removal of the surface layer of natural WSLs. Moreover, the effect of resin infiltration was similar to the control group which was pretreated 15% HCl gel for 120s in vitro study. CLINICAL SIGNIFICANCE For resin infiltration, applying 37% H3PO4 gel with a brush applicator can preserve the protective surface layers of the WSLs with reduced application time.

An in vitro comparison of quantitative light-induced fluorescence-digital and spectrophotometer on monitoring artificial white spot lesions

PURPOSE The aim of this study was to evaluate the efficacy of quantitative light-induced fluorescence-digital (QLF-D) compared to a spectrophotometer in monitoring progression of enamel lesions. METHODS To generate artificial caries with various severities of lesion depths, twenty bovine specimens were immersed in demineralizing solution for 40 days. During the production of the lesions, repeat measurements of fluorescence loss (ΔF) and color change (ΔE) were performed in six distinct stages after the demineralization of the specimens: after 3, 5, 10, 20, 30, and 40 days of exposure to the demineralizing solution. Changes in the ΔF values in the lesions were analyzed using the QLF-D, and changes in the ΔE values in lesions were analyzed using a spectrophotometer. The repeated measures ANOVA of ΔF and ΔE values were used to determine whether there are significant differences at different exposure times in the demineralizing solution. Spearmans rank correlation coefficient was analyzed between ΔF and ΔE. RESULTS AND CONCLUSION The ΔF values significantly decreased based on the demineralizing period (p<0.001). Relatively large changes in ΔF values were observed during the first 10 days. There were significant changes in L(*), a(*), b(*), and ΔE values in lesions with increasing demineralizing duration (p<0.001). A strong correlation was observed between ΔF and ΔE with p=-0.853 (p<0.001). The results support the efficacy of QLF-D in monitoring color changes. Our findings demonstrate that QLF-D are a more efficient and stable tool for early caries detection.