• 대한치과의사협회지
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• 제56권1호
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• pp.8-16
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• 2018

Purpose: The aim of in vitro study was to compare the diagnostic accuracy to detect non-cavitated enamel caries on smooth surface by using four kinds of the QLF devices. Materials and Methods: A total of 52 human permanent premolars and molars were used. Fluorescence images were captured by the QLF devices (Inspektor Pro, QLF-D, Qraycam, and Qraypen). Fluorescence loss of the QLF was calculated. The severity of lesions was categorized into the following 3 scores using polarized light microscopy: normal (S), enamel demineralization to outer half of enamel (D1), and inner half of the enamel up to the dentin-enamel junction (D2). The Kruskal-Wallis test was used to compare the fluorescence loss among the QLF devices. Spearman rank correlation coefficient between histological scores and fluorescence loss of the devices was calculated. The sensitivity, specificity, and area under the receiver operating curve (AUROC) were calculated to compare their diagnostic accuracies. Results: The correlation coefficients between histological scores and the fluorescence loss of the devices showed 0.77 to 0.81 (P < 0.001). All histological scores, the fluorescence loss among the devices showed no statistical difference. Among the devices, sensitivity, specificity, and AUC values of the fluorescence loss showed 0.84 to 0.94, 0.76 to 0.90, and 0.90 to 0.92, respectively. Conclusions: All QLF devices had no difference with excellent diagnostic accuracies to detect non-cavitated enamel caries on smooth surface.

• Current Optics and Photonics
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• 제6권1호
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• pp.86-91
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• 2022

Two-photon fluorescence microscopy was performed on the enamel-dentin junction area of a human tooth using a femtosecond pulsed laser. We obtained a clear image contrast between the bright dentin and dark tubules with the autofluorescence generated from the endogenous fluorophores in dentin. The autofluorescence shows a broad spectrum due to complex cross links between dentinal collagens, which extend from blue to orange wavelengths (470-590 nm), but a gradual autofluorescence loss in photobleaching was observed for a long-term exposure under strong excitation. For increasing excitation power, we found that two-step decay becomes significant in the spectrally integrated autofluorescence.

• Bulletin of the Korean Chemical Society
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• 제10권2호
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• pp.142-147
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• 1989

Fluorescence enhancements of ethidium bromide (EB) by solution species of low molecular weights such as DNA base molecules and nucleosides in water are reported. The degree of enhancements was determined by intensity as well as lifetime measurements for EB fluorescence. Experiments including solvent effects on absorbance and fluorescence spectra of EB, effects of protonation on the EB absorbance spectrum, and determination of equilibrium constants for EB-DNA bases have been performed to help explain the fluorescence enhancement. The results suggest that the excited state stabilization in the hydrophobic environment, the loss of torsional/vibrational energy of amino groups, and the change in the electronic transition characteristics are all responsible for the fluorescence enhancement.

• 치위생과학회지
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• 제19권3호
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• pp.154-161
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• 2019

Background: The market for vitamin drinks is expanding both in Korea and worldwide. However, it was difficult to find studies regarding the possibility of tooth erosion induction due to vitamin drinks. The purpose of the present in vitro study was to evaluate the effect of tooth erosion caused by a few commercial vitamin beverages on bovine teeth enamel in terms of erosion depth and fluorescence loss. Methods: Three experimental groups (vitamin drinks), a positive control group (Coca-Cola), and a negative control group (mineral water) were established. Each group consisted of 5 specimens obtained from sound bovine teeth. The pH and titratable acidity of beverages were measured. Specimens were immersed in the beverages and artificial saliva for 6 and 18 hours, respectively. This cycle was repeated for 5 days. The depth of the tooth loss caused by tooth erosion (erosion depth) and maximum loss of fluorescence (Max ${\Delta}F$) were measured using the microscope and quantified light-induced fluorescence-digital, respectively. For the statistical analysis, the Kruskal-Wallis test and ANOVA were used to compare the erosion depth and Max ${\Delta}F$ of the enamel surfaces. In addition, Spearman correlations were estimated. Results: The pH of the three vitamin beverages ranged from 2.65 to 3.01, which is similar to that of the positive control group. All beverages, except mineral water, had sugar and acidic ingredients. Vitamin drinks and the positive control, Coca-Cola, caused tooth erosion lesions, and showed significant differences in erosion depth compared to mineral water (p<0.05). The vitamin beverages with low pH were associated with high erosion depth and Max ${\Delta}F$. Conclusion: Vitamin drinks have the potential to cause tooth erosion.

• International Journal of Industrial Entomology and Biomaterials
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• 제45권2호
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• pp.56-69
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• 2022

Silk is a unique natural biopolymer with outstanding biocompatibility, high mechanical strength, and superior optical transparency. Due to its excellent properties, silk has been widely reported as an ideal biomaterial for several biomedical applications. Recently, fluorescent silk protein, a variant of native silk, has been reported as a biophotonic material with the potential for bioimaging and biosensing. Despite the realization of fluorescent silk, the traditional degumming process of fluorescence silk is crude and often results in fluorescence loss. The loss of fluorescent properties is attributed to the sensitivity of silk fibroin to temperature and solvent concentration during degumming. However, there is no comprehensive information on the influence of these processing parameters on fluorescence evolution and decay during fluorescent silk processing. Therefore, we conducted a spectroscopic study on fluorescence decay as a function of temperature, concentration, and duration for fluorescent silk cocoon degumming. Sodium carbonate solution was tested for degumming the fluorescent silk cocoons with different concentrations and temperatures; also, sodium carbonate solution is combined with Alcalase enzyme and triton x-100 to find optimal degumming conditions. Additionally, we conducted a molecular dynamics study to investigate the fundamental effect of temperature on the stability of the fluorescent protein. We observed degumming temperature as the prime source of fluorescent intensity reduction. From the MD study, fluorescence degradation originated from the thermal agitation of fluorescent protein Cα atoms and fluctuations of amino acid residues located in the chromophore region. Overall, degumming fluorescent silk with sodium carbonate and Alcalase enzyme solution at 25 ℃ preserved fluorescence.

• The Journal of Advanced Prosthodontics
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• 제9권6호
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• pp.432-438
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• 2017

PURPOSE. The purpose of this study was to evaluate the in vitro validity of quantitative light-induced fluorescence-digital (QLF-D) and laser fluorescence (DIAGNOdent) for assessing proximal caries in extracted premolars, using digital radiography as reference method. MATERIALS AND METHODS. A total of 102 extracted premolars with similar lengths and shapes were used. A single operator conducted all the examinations using three different detection methods (bitewing radiography, QLF-D, and DIAGNOdent). The bitewing x-ray scale, QLF-D fluorescence loss (${\Delta}F$), and DIAGNOdent peak readings were compared and statistically analyzed. RESULTS. Each method showed an excellent reliability. The correlation coefficient between bitewing radiography and QLF-D, DIAGNOdent were -0.644 and 0.448, respectively, while the value between QLF-D and DIAGNOdent was -0.382. The kappa statistics for bitewing radiography and QLF-D had a higher diagnosis consensus than those for bitewing radiography and DIAGNOdent. The QLF-D was moderately to highly accurate (AUC = 0.753 - 0.908), while DIAGNOdent was moderately to less accurate (AUC = 0.622 - 0.784). All detection methods showed statistically significant correlation and high correlation between the bitewing radiography and QLF-D. CONCLUSION. QLF-D was found to be a valid and reliable alternative diagnostic method to digital bitewing radiography for in vitro detection of proximal caries.

• 한국세라믹학회지
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• 제37권8호
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• pp.781-786
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• 2000

An Er-doped sulfide fiber was drawn, and its spectroscopic properties were analyzed. Compositions of a 1000 ppmwt Er3+-doped core and an undoped clad were Ge30-Ga1-Asg-S61 and Ge30-As8-S62, in at.%, respectively. Refractive index of the core composition was approximately 0.01 high than that of the clad. In order to enhance the mechanical stability as well as to prevent infiltration of impurity ions such as OH-, an UV-curable polymer was used for the coating. The optical loss of a fiber formed directly from a polymer coated core rod without cladding was ∼15 dB/m at 1.06$\mu\textrm{m}$. In the case of a fiber with core/clad structure, the optical loss was so high that the stimulated emission of erbium fluorescence was not evident. It is believed that presence of inhomogeneous core/clad interface and crystalline aggregates precipitated in the clad region were responsible for the high optical loss. On the other hand, fluorescence characteristics of Er3+ embedded in the core region were more or loss deteriorate compared to fiber preform, which is attributed to the redistribution of the Er ions along with the partial crystallization of the core glass during the fiberization process.

• 한국진공학회지
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• 제18권6호
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• pp.418-425
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• 2009

권역별 싸이클로트론연구소에 설치되어 있는 KIRAMS-13 싸이클로트론에서 안정적이고 최적화된 양성자빔을 인출하기 위해서는 양성자빔의 횡단면 측정이 필수적이다. 빔의 횡단면 측정장치 중 비파괴적인 방법인 BIF(Beam Induced Fluorescence) 모니터는 그 구조가 상대적으로 간단하고 빔의 에너지 손실을 최소화하며 실시간 측정이 가능하다는 장점이 있다. 이 연구에서는 KIRAMS-13 싸이클로트론에서 양성자빔의 횡단면 측정을 위한 BIF 모니터를 설계하고 제작한 후 13 MeV 양성자빔 조사실험을 통하여 양성자 빔의 중심 및 반경을 측정하였다.

• 치위생과학회지
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• 제17권2호
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• pp.116-122
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• 2017

본 연구는 QLF-D를 이용하여 와동 내벽에 형성된 초기 이차우식증을 탐지가 가능한지 평가해보고, 표면에서 관찰한 우식병소와 실제 와동 내벽에 발생한 병소 간에 차이가 있는지 확인해보고자 시행하였으며, 다음과 같은 결과를 얻었다. 시간의 흐름에 따라 시편의 표면에서 관찰되는 이차우식병소가 점점 진행되었다. 수복물 변연의 우식병소 부분이 수복물에 가려지거나 형광에 의해 우식부분을 육안으로 판단하기에 어려운 부분들이 보였으며, 수복물이 있는 경우의 ${\Delta}F$값은 $-14.20{\pm}3.24$, 와동만 있는 경우의 ${\Delta}F$값은 $-11.56{\pm}3.94$ 로 수복물이 있는 경우의 ${\Delta}F$값이 유의하게 높게 나타났다(p<0.001). 또한 수복한 표면에서 측정한 병소의 ${\Delta}F$값은 $-14.20{\pm}3.24$, 횡단면에서 측정한 병소의 ${\Delta}F$값은 $-18.64{\pm}3.75$로 횡단면보다 표면에서 측정한 병소의 ${\Delta}F$값이 약 1.31배 가량 유의하게 크게 나타났으며, correlation은 0.026으로 낮게 나타났다(p<0.001). 하지만 수복하지 않은 표면과 횡단면의 ${\Delta}F$값 간의 correlation값은 0.613으로 높게 나타났다. 이를 통해 QLF-D를 이용하여 표면에서도 이차우식병소의 탐지가 가능하다는 것을 알 수 있었다. 다만, 수복물에 의한 간섭이 있을 수 있고, 병소의 특성상 실제 병소의 심도보다 적게 측정될 수 있으므로 이에 대한 고려를 통한 탐지가 이루어져야 할 것이다.

• 한국치위생학회지
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• 제16권4호
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• pp.525-530
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• 2016

Objectives: The purpose of the study is to investigate remineralization effect according to application cycle of fluoride varnish in preschool children. Methods: The study subjects were fifty six children (92 teeth) having one or more early dental caries lesion. Fluoride varnish was applied to the primary area of maxillary and anterior mandibular teeth with the interval of one month, three months, and six months. Results: Dft index was 3.54 in male and 3.44 in female. The fluorescence loss(${\Delta}F$) value due to early caries lesions showed a significant difference in experiment groups I and II after the application of fluoride varnish, but there was no significant difference in experiment group III. After fluoride varnish application, there was a significant change in experimental group I and III. The maximum fluorescence loss(${\Delta}Fmax$) from early caries lesions showed a significant difference after application of the fluoride varnish in all three experiment groups of I, II, and III(p<0.001). Conclusions: Fluoride varnish should be recommended and applied to the children of high risk caries group in every three months.