Evaluation of the clinical efficacy of quantitative light-induced fluorescence technology in diagnosing cracked teeth.

BACKGROUND: This retrospective study evaluated the clinical efficacy of quantitative light-induced fluorescence (QLF) technology for crack detection and the diagnosis of cracked teeth and assessed the possibility of a quantitative evaluation of cracks using QLF technology. METHODS: Patients who were clinically diagnosed with cracked teeth over a 1-year period were included. The QLF images of the corresponding symptomatic cracked teeth and asymptomatic contralateral teeth with crack lines were taken with Qraypen C (AIOBIO, Seoul, Korea). Fluorescence loss (ΔF), maximum fluorescence loss (ΔFmax), red fluorescence (ΔR), and maximum red fluorescence (ΔRmax) of the crack line were analyzed. The correlation between these parameters and sex, age, tooth position (1st premolar, 2nd premolar, 1st molar, 2nd molar), spontaneous pain (+/-), percussion test (+/-), cold test (++/+/-), and bite test (+/-) were statistically analyzed. RESULTS: A total of 66 patients were included. Twenty-four patients had asymptomatic contralateral teeth with apparent crack lines; thus, 90 teeth were analyzed. The crack lines in 84 teeth observed as red fluorescent lines on the QLF images showed ΔR values higher than the cut-off value set by the analysis program used. The patient's age and the ∣ΔF∣ and ΔR values were positively correlated. However, there was no statistically significant difference in the QLF parameters between the same patient's symptomatic tooth and the contralateral tooth. CONCLUSIONS: QLF technology is a useful assistive diagnostic device for diagnosing cracked teeth.

Can red fluorescence be useful in diagnostic decision making of residual dentin caries?

INTRODUCTION: A diagnosis based on traditional methods can differ under the same tooth condition. Additional diagnostic tools are required to overcome this limitation. QLF technology is a viable method for detecting residual caries and is increasingly being used to detect dentin-level residual caries. In this study we used the Qraypen (AIOBIO, Seoul, Korea) to investigate the usefulness of the QLF technology for diagnosing controversial cases. CASE 1: A 31-year-old man presented with pain in the left mandibular first molar. The old restoration and severe dental caries were removed as much as possible using traditional visual and tactile senses. The area of treatment was photographed using the Qraypen. We concluded that endodontic treatment was preferable based on the Qraypen findings combined with diagnostic information. CASE 2: A 67-year-old man presented with discomfort in the first molar on the right mandible. Most of the existing restoration and carious debris were removed. Black discoloration was observed around and within the crack line, but with no red fluorescence. Based on the results of these examinations we decided that a minimally invasive dentistry approach was appropriate. CONCLUSION: Using QLF technology is more objective and accurate than other methods of determining the removal end point and detecting healthy marginal dentin for successful restoration.

Evaluation of tooth wear by estimating enamel thickness with quantitative light-induced fluorescence technology.

BACKGROUND: Various techniques have been suggested to quantitatively assess tooth wear; most have limited clinical application. The first aim of this in vitro study was to estimate the residual enamel thickness of teeth with various degrees of occlusal wear using quantitative light-induced fluorescence (QLF). The second aim was to identify relationships between the fluorescence parameters of QLF and the conventional tooth wear index (TWI) system. METHODS: Sixty-nine extracted permanent premolars and molars with initial stages of tooth wear (TWI score 1a-2: enamel wear to dentin exposure) were used. Two blinded and trained examiners participated in evaluation procedures. Occlusal QLF-digital (QLF-D) images were acquired for selecting area of interest (AOI) and calculating fluorescence for occlusal tooth wear (ΔFwear) of the AOI by the first examiner. Each specimen was cross-sectioned in the buccal-lingual direction. Enamel thickness from images obtained by stereomicroscopy and TWI of each sample was determined by the second examiner. Spearman correlation was used to determine the relationship of ΔFwear with enamel thickness and TWI. ΔFwear values were compared between histological scores with the Mann-Whitney U test. RESULTS: Seventy-six AOIs were analyzed. As enamel thickness decreased, ΔFwear values significantly increased and strongly correlated with enamel thickness (Spearman rho = -0.825, P < 0.001). There were significant differences in ΔFwear values among TWI scores (P < 0.001); ΔFwear strongly correlated with TWI (Spearman rho = 0.753, P < 0.001). CONCLUSIONS: ΔFwear values, which denote fluorescence difference by using QLF, showed a strong correlation with residual enamel thickness and tooth wear severity.

Assessment of tooth wear based on autofluorescence properties measured using the QLF technology in vitro.

BACKGROUND: The difference in autofluorescence between enamel and dentine layer has prompted recommendations to use the quantitative light-induced fluorescence (QLF) method for quantifying tooth wear (TW). This study investigated the potential of QLF for distinguishing the severity of occlusal TW based on differences in the autofluorescence intensity. METHODS: In total, 106 extracted permanent molars and premolars having suspected wear without pulp exposure were used. The severity of wear was determined by visually examining all teeth using the tooth wear index (TWI) of Smith and Knight. QLF images were captured and converted into 8-bit grayscale images. The difference in the fluorescence intensity (ΔG) was calculated by comparing mean grayscale levels between sound and worn areas. Finally, histological examination was conducted by stereomicroscope to confirm the presence of dentine exposure. RESULTS: 100 teeth were included in the final analysis without six teeth having enamel cracks around worn area. The ΔG values increased with the severity of TW as quantified using conventional TWI codes, and differed significantly between the sound and enamel- and dentine-wear teeth (P < 0.001). The histology indicated that enamel remained on 57 teeth, while 43 teeth had dentine-exposed wear and showed significant differences in ΔG compared with enamel-remained teeth. CONCLUSIONS: The fluorescence intensity differed significantly depending on the presence of dentine exposure. ΔG could be used to distinguish between sound and enamel- and dentine-wear teeth with a significant correlation. These findings indicate that QLF could be useful for determining the severity of TW of occlusal surfaces noninvasively.

Application of quantitative light-induced fluorescence technology for tooth bleaching treatment and its assessment: An in vitro study.

OBJECTIVES: This study aimed to determine the efficacy of a combination of photocatalysts-hydrogen peroxide at a low concentration (3.5%) and titanium dioxide (TiO2)-activated at a wavelength of 405 nm using quantitative light-induced fluorescence (QLF) technology, and to quantify their tooth-bleaching efficacy using fluorescence images obtained from QLF technology. MATERIALS AND METHODS: Forty bovine incisors were extrinsically stained according to Stookey's method, and were randomly divided into four groups (n = 10 per group). Two bleaching solutions were prepared by mixing 3.5% H2O2 with 0.05% of anatase and rutile TiO2 powders. These solutions were applied to the stained teeth using a microbrush and then irradiated for 15 min at either 306 or 405 nm to activate the bleaching agent. The color difference (ΔE*) was assessed before and after every 5 min of treatment. The ΔE* and the changes in the fluorescence loss (ΔΔF) were obtained from white-light and fluorescence images, respectively. RESULTS: All of the low-H2O2/TiO2 treatments caused significant tooth-bleaching efficacy after irradiation at 306 and 405 nm (p < 0.05). The results did not differ significantly between the two wavelengths (p > 0.05), but the bleaching efficacy was greater with anatase TiO2 at 306 nm and rutile TiO2 at 405 nm. Analysis of the fluorescence images revealed that the ΔF values increased significantly in all groups with the treatment time (p < 0.05). There was a statistically significant correlation between ΔE* and the change in ΔΔF (r = 0.822, p < 0.001). CONCLUSIONS: Combining low-H2O2/TiO2 with QLF technology at 405 nm has an efficacy of tooth-bleaching as a less harmful and biofriendly method, while the fluorescence images obtained by QLF technology could be used to assess tooth-bleaching.

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.

Validation of Quantitative Light-Induced Fluorescence for Quantifying Calculus on Dogs' Teeth.

Periodontal disease is a common disease of dogs and is initiated by the buildup of plaque on the tooth surface. As plaque matures, it becomes mineralized to form calculus, which although not directly involved in the etiology of periodontal disease, provides an irregular surface to which plaque can adhere. Evaluation of the quantity of plaque and calculus on dogs' teeth is therefore essential to enable the efficacy of products, designed to prevent or retard plaque and calculus accumulation, to be evaluated. The objective of this study was to determine whether quantitative light-induced fluorescence (QLFTM) is a suitable tool to quantify the amount of calculus on the buccal surface of dogs' teeth following the removal of disclosed plaque by tooth brushing. The amount of calculus on the teeth of 26 miniature schnauzers was measured, using QLF and a calculus index method (Warrick-Gorrel), during a 28-day phase crossover study comparing feeding a daily dental chew versus providing no daily chew. Quantification of calculus using the Warrick-Gorrel method showed a 43.8% reduction in calculus buildup, with 95% confidence interval of 27.3 to 60.3 ( P < .001). With QLF, the percentage reduction in calculus accumulation was 65.8% (58.1-73.4, P < .001). A retrospective sample size analysis showed that fewer dogs were required for QLF analysis compared to the Warrick-Gorrel method. This study demonstrated that QLF is a sensitive and precise method for quantification of calculus on dogs' teeth. It removes the subjective element of human examiners and has greater accuracy and reduced variability through the continuous nature of the data.

Prediction of early caries prognosis after fluoride application based on the severity of lesions: An in situ study.

PURPOSE: The aim of this in situ study was to measure baseline fluorescence loss values (ΔF(0)) using the quantitative light-induced fluorescence (QLF) technology to screen enamel lesions for effective remineralization following fluoride application. METHODS: In this single-blinded in situ study, 20 adult volunteers wore intraoral appliances containing 4 specimens of human enamel. The surfaces of the specimens were divided into 3 regions: sound, demineralized, and treated regions. After generating 80 artificial enamel lesions with varying ΔF values, all specimens were covered with 1.23% acidulated phosphate fluoride gel for 1 min. Three repeated QLF-digital measures of ΔF values were then obtained for the lesions, immediately after demineralization and at 1 and 4 weeks after fluoride application. RESULTS AND CONCLUSION: Fluoride application was found to increase the ΔF values of lesions significantly over time (p < 0.001). The groups with lower ΔF(0) values showed significantly larger changes in ΔF values over time (p < 0.001). Receiver operating characteristics analysis showed that baseline lesion values of ΔF(0) = -17.50 and -25.50 would allow for lesion ΔF to recover to -10 at 1 and 4 weeks after fluoride application, respectively (p < 0.001). The findings of this study indicate that clinicians can establish prognostic criteria for early carious lesions using the QLF technology, and hence predict the efficacy of fluoride treatment and devise effective lesion-specific treatment plans.

Optical diagnosis of dentin caries lesions using quantitative light-induced fluorescence technology.

The precise diagnosis of dental caries and determination of their severity are very important when planning for treatment. Low diagnostic power of traditional methods such as radiographic and visual-tactile examinations could increase in the ambiguity of clinical decision about some borderline lesions. The aim of this study was to identify the extent of dentin lesions by using Qraypen (AIOBIO, Seoul, Korea), a device that utilizes QLF technology, at the dentin level through representative 2 cases in this study. In the first case of chronic and deep dentin caries, the fluorescence loss and strong red fluorescence were still detected from the lesions when observed by Qraypen after removing the suspicious lesions using conventional methods. It was possible to gradually remove red fluorescent area until it reached an almost invisible state. In addition, from the second case of acute and secondary caries, it was difficult to detect the crack using conventional diagnostic methods. Based on the result of the Qraypen examination, we could verify the presence of the crack and its severity which had progressed into the pulp as a distinct red fluorescence. In conclusion, the QLF technology could be applied not only to detect dentin caries but also to provide evidences for determining extent of caries removal non-invasively and objectively.