Detection of pit and fissure sealant microleakage using quantitative light-induced fluorescence technology: an in vitro study.

This in vitro study aimed to evaluate the feasibility of quantitative light-induced fluorescence (QLF) technology for detecting the presence and severity of microleakage of pit and fissure sealants. The areas of interest (AOIs) were 160 pits and fissures of 40 extracted permanent teeth. Fluorescent images were acquired using a QLF device, and the maximum fluorescence loss ΔFmax of each AOI was analyzed. After staining and cross-sectioning of the teeth, histological dye penetration was scored on a scale of 0 to 3. The relationship between ΔFmax and microleakage depth was analyzed, and the areas under the curve (AUCs) were calculated. The │ΔFmax│ increased as microleakage depth increased. The ΔFmax values of microleakage areas showed a strong significant correlation with the histological scores of dye penetration (r = - 0.72, P = 0.001). AUC analysis showed a high diagnostic accuracy for microleakage depth (AUC = 0.83-0.91). The highest AUC of 0.91 was found when differentiating the outer half microleakage of the sealant (histological score 0 vs. 1-3). QLF technology is effective in assessing the presence and severity of microleakage, suggesting its potential for noninvasive detection and monitoring of sealant microleakage in clinical settings.

Anti-biofilm activity of a novel nanoemulsion containing Curcuma xanthorrhiza oil.

OBJECTIVES: We aimed to solubilize Curcuma xanthorrhiza oil (CXO) using nanoemulsification and evaluate its inhibitory effects against biofilm formation. METHODS: The components of CXO were evaluated through high-performance liquid chromatography (HPLC) analysis. Healthy human saliva was inoculated onto hydroxyapatite discs to form microcosm biofilms for four days and treated six times with each antimicrobial agent: distilled water (DW), CXO emulsion (EM), CXO nanoemulsion (NE), and positive controls (Listerine and chlorhexidine). Biofilm fluorescence imaging was performed using quantitative light-induced fluorescence, and cell viability and dry-weight measurements were obtained. We compared the bacterial cell and extracellular polysaccharide (EPS) biovolume and thickness using confocal laser scanning microscopy (CLSM). RESULTS: HPLC analysis revealed that CXO was composed of approximately 47% xanthorrhizol. Compared with DW, NE exhibited significantly lower red fluorescence intensity and area (42% and 37%, p < 0.001 and p < 0.001, respectively), and reduced total and aciduric bacterial cell viability (7.3% and 3.9%, p < 0.001, p = 0.01, respectively). Furthermore, the bacterial cell and EPS biovolume and thickness in NE decreased by 40-80% compared to DW, similar to chlorhexidine. Conversely, EM showed a significant difference only in cell viability against total bacteria when compared with DW (p = 0.003), with EPS biovolume and thickness exhibiting higher values than DW. CONCLUSIONS: Nanoemulsification successfully solubilized CXO and demonstrated superior anti-biofilm effects compared to the emulsion form. CLINICAL SIGNIFICANCE: These findings suggest the potential use of NE as a novel antimicrobial agent for preventing oral diseases.

Real-time optical detection of endodontic infection using bacterial autofluorescence.

OBJECTIVES: For successful root canal treatment (RCT), it is essential to objectively assess the presence and activity of bacteria in the root canal system. However, current methods rely on subjective observations of root canal exudates. This study aimed to confirm whether real-time optical detection using bacterial autofluorescence can evaluate endodontic infection status by assessing the red fluorescence (RF) detected from root canal exudates. METHODS: During RCT, endodontic paper points were used to collect root canal exudates scored using conventional organoleptic tests to assess the severity of root canal infections. RF on the paper points was assessed using quantitative light-induced fluorescence (QLF) technology. RF intensity and area from the paper points were quantified, and their correlations with infection severity were assessed using their organoleptic scores. The oral microbiome composition of RF samples was compared with non-red fluorescent (non-RF) samples. RESULTS: The RF detection rate was nil and >98% in the non-infectious and severe groups. The RF intensity and area significantly increased with infection severity (p<0.001) and showed strong correlations with organoleptic scores (r=0.72, 0.82, respectively). The diagnostic accuracy for detecting root canal infection using RF intensity was good to excellent (AUC = 0.81-0.95) and increased with infection severity. The microbial diversity of the RF samples was significantly lower than that of the non-RF samples. Gram-negative anaerobic bacteria such as Prevotella and Porphyromonas were more predominant in RF samples. CONCLUSIONS: Optical detection using bacterial autofluorescence can objectively evaluate endodontic infection status in real-time by assessing the RF of endodontic root canal exudates. CLINICAL SIGNIFICANCE: This real-time optical technology can be utilised to detect endodontic bacterial infection without conventional incubation, allowing clinicians to determine the endpoint of chemomechanical debridement and increase the positive outcomes of RCTs.

Periodontal disease and cancer risk: A nationwide population-based cohort study.

Background: Although emerging evidence suggests that periodontitis might increase the risk of cancer, comorbidity and lifestyle behaviors, such as smoking and body mass index (BMI), may have confounded this reported association. This study aimed to investigate whether chronic periodontitis is associated with cancer risk using a large, nationwide database. Methods: We conducted a population-based, retrospective cohort study using data from the Korean National Health Insurance Cohort Database obtained between January 2003 and December 2015. We included 713,201 individuals without a history of cancer who were followed up to 10 years. Confounding factors included demographic factors (age, sex, income, and residential area), lifestyle behaviors (smoking history and BMI), and comorbidities, such as hypertension, diabetes, heart failure, and pulmonary disease, using the Charlson Comorbidity Index. Multivariable Cox regression analysis was applied to estimate the adjusted hazard ratio (aHR) for cancer risk. Results: Of the 713,201 participants, 53,075 had periodontitis and were placed in the periodontitis group; the remaining 660,126 individuals were included as the control group. Overall, the cumulative incidence of cancer in the periodontitis group was 2.2 times higher than that in the control group. The periodontitis group had an increased risk of total cancer compared to the control group after adjusting for age, sex, comorbidities, BMI, and smoking history (aHR, 1.129; 95% confidence interval [CI], 1.089-1.171; P<0.0001). When examining specific cancer types, significant associations were also observed between periodontitis and stomach cancer (aHR, 1.136; 95% CI, 1.042-1.239; P=0.0037), colon cancer (aHR, 1.129; 95% CI, 1.029-1.239; P=0.0105), lung cancer (aHR, 1.127; 95% CI, 1.008-1.260; P=0.0353), bladder cancer (aHR, 1.307; 95% CI, 1.071-1.595; P=0.0085), thyroid cancer (aHR, 1.191; 95% CI, 1.085-1.308; P=0.0002), and leukemia (aHR, 1.394; 95% CI, 1.039-1.872; P=0.0270). There was no significant association between the development of secondary malignancy and periodontitis in cancer survivors who were alive 5 years after they were diagnosed with the primary malignancy. Conclusions: Periodontal disease, including periodontitis, was associated with increased risk of cancer, which persisted after controlling for confounding factors. Further prospective research is warranted to establish a causal relationship.

Lesion activity assessment of early caries using dye-enhanced quantitative light-induced fluorescence.

We aimed to determine whether dye-enhanced quantitative light-induced fluorescence (DEQLF), wherein porous structure of caries lesions is stained with a fluorescent dye, could quantitatively distinguish between active and inactive caries. A total of 126 bovine specimens were prepared to artificially simulate caries activity. Active caries were demineralized with 1% carbopol solution for 3 (A3), 5 (A5), and 10 days (A10). For inactive caries, half specimens in each group were remineralized with 2% NaF and reallocated into three groups (I3, I5, and I10, respectively). Wet specimens were dried with compressed air for 10 s and then dyed with 100-µM sodium fluorescein for 10 s. Fluorescence images of speicmens were captured with a QLF-digital 2 + Biluminator. Fluorescence intensity (ΔG) was measured in fluorescence images of dyed specimens. ΔG between active and inactive groups was compared using independent t-test, and ΔG among active groups (or inactive groups) were compared using ANOVA (α = 0.05). ΔG in the active groups was 33.7-59.0 higher than that in the inactive groups (P < 0.001). Except between I3 and I5, there was significant differences in ΔG according to the demineralization period (P < 0.001). DEQLF might be used to evaluate early caries activity, and longitudinally monitor changes in lesion activity.

Optical detection of oral biofilm in hospitalized geriatric patients using quantitative light-induced fluorescence technology.

Detection and removal of pathological oral biofilm are essential in hospitalized geriatric patients as the biofilm can lead to lung infection. However, as elderly patients often have cognitive and physical impairments, general oral examination is complicated and detection of pathological biofilms is challenging. Quantitative light-induced fluorescence (QLF) technology, which is currently actively used to detect bacterial structures in the oral cavity, is used to detect dental biofilm and to identify various oral bacterial infections. We confirmed the applicability of QLF technology to oral hygiene assessment and evaluation of hospitalized geriatric patients using the QLF technology to detect and remove the pathological oral biofilm in a hospitalized geriatric patient. The oral biofilm attached to the oral mucosa was difficult to observe with the naked eye. However, it was detected with red fluorescence on QLF images, which helped us observe the to detect pathological oral biofilm and evaluate the effectiveness of oral hygiene care (OHC). After OHC, the strong red fluorescence expressed in the oral mucosa was no longer observed. This change in the clinical aspect of red fluorescence suggests that QLF can be used to detect pathological oral biofilm accumulated on the oral mucous membrane and evaluate the effectiveness of OHC in hospitalized patients with extremely poor oral hygiene.

Anti-biofilm activity of chlorhexidine-releasing elastomerics against dental microcosm biofilms.

OBJECTIVE: To evaluate the anti-biofilm activity of chlorhexidine-releasing elastomerics (CRE) developed to prevent biofilm-related diseases in orthodontic patients, using dental microcosm biofilms. METHODS: Elastomerics coated with one of two solutions (CRE 1 and 2) were attached to bovine enamel specimens. Uncoated elastomerics were used for negative (distilled water [DW]) and positive (0.1% chlorhexidine [CHX]) control groups. After saliva inoculation on the surface of the specimen for biofilm formation, DW and CRE groups were treated with DW, and the positive control group was treated with CHX twice a day for 5 min. After 7 days of biofilm formation, colony-forming units (CFUs, total and aciduric bacteria), red/green (R/G) ratio, biofilm thickness, live/dead cell ratio, and bacterial morphology in the biofilms were evaluated. Enamel demineralization was evaluated by fluorescence loss (ΔF). RESULTS: The CFUs of total and aciduric bacteria and R/G ratios in the CRE groups were significantly lower than those in the DW group with a reduction by 13%, 13%, and 19%, respectively (p < 0.05). The CFUs of total bacteria was significantly lower in the CRE groups than in the 0.1% CHX group (p < 0.05). Among the CRE groups, only CRE 1 exhibited a significantly reduced biofilm thickness of 54% compared to the DW group (p < 0.05) and apparent changes in bacterial morphology. ΔF in the CRE groups was significantly higher by 36% compared to that in the DW group (p < 0.05). CONCLUSIONS: CREs exhibited anti-biofilm and demineralization-inhibiting effect. Particularly, CRE 1 using dichloromethane as the solvent was most effective against biofilms. CLINICAL SIGNIFICANCE: Chlorhexidine-releasing elastomerics exhibited increased anti-biofilm and demineralization-inhibiting effect compared to 0.1% chlorhexidine mouthwash. Therefore, it is possible to prevent biofilm-related diseases simply and effectively by applying chlorhexidine-releasing elastomerics to orthodontic patients.

Red fluorescence for assessing longitudinal tooth fractures.

BACKGROUND: This study was designed to determine whether autofluorescence emitted from longitudinal tooth fractures (LTFs) differs between fracture types, with the aim of determining which clinical factors are related to red fluorescence at the fracture line. METHODS: Thirty-three extracted teeth were classified into cracked teeth, split teeth, and root fractures using LTF types according to the American Association of Endodontists classification. The types of LTFs were identified using an operating microscope. LTF autofluorescence was captured using a fluorescence technique. Clinical examinations were performed using the preoperative factors from clinical and radiographic findings. RESULTS: Red fluorescence was identified in 82% and 83% of cracked and split teeth, respectively. None of the vertical root fractures exhibited red fluorescence (p<0.001). When red fluorescence was identified on the outer tooth surface, it penetrated into the crack line, but fluorescence that was not red at the tooth surface did not penetrate the fracture line. Among the examined preoperative clinical factors, differences between the presence and absence of red fluorescence were identified for sinus tract formation (p = 0.021), and radiographic features (p = 0.027). Regression analysis revealed a significant factor related to the red fluorescence, with sinus tract formation having a negative effect on red fluorescence (odds ratio [OR]=0.09). The presence of comprehensive periradicular lesions in radiography had a positive effect on red fluorescence (OR=5.04). CONCLUSIONS: Cracks originating from tooth crowns in certain types of LTFs were associated with red fluorescence, and cracks with red fluorescence were associated with extensive periodontal bone resorption around the teeth roots.

Teaching Cariology in Asia and Arabia.

The European Organisation for Caries Research education platform 2020 had the aim to assess the undergraduate curriculum in cariology in Asian and Arabian countries in order to support structured teaching of cariology in these countries with about almost half of the global population. Representatives of 4 Asian and 4 Arabian countries completed a comprehensive questionnaire on structure of dental education in their country in general and the extent, the content, the responsibilities, structure and standardization regarding cariology in particular. In spite of a wide range from very few universities (Lebanon 3) to larger numbers of dental schools (India 313, China 121, Russia 52) there were similar statements on the list of content for cariology teaching. Often the catalogue was close to the Undergraduate Core Curriculum in Cariology (UCCC) covering most of the 5 domains from basic science to dental public health, but a national curriculum for cariology or dentistry was mostly missing. With various departments being involved, a need of coordination is obvious. Most representatives thought it possible and feasible to teach a standardized curriculum in cariology on the basis of the UCCC. In conclusion, many Arabian and Asian countries have implemented modern, evidence-based curricula in their universities, but an obligatory national curriculum in cariology would be advisable to standardize the quality in teaching.

A novel model to predict tooth bleaching efficacy using autofluorescence of the tooth.

OBJECTIVES: We aimed to confirm whether autofluorescence emitted from teeth can predict tooth bleaching efficacy and establish a novel model combining natural color parameters and tooth autofluorescence data to improve the predictability of tooth bleaching. METHODS: A total of 61 tooth specimens were prepared from extracted human molars/premolars and immersed in 35% hydrogen peroxide for 1 h for tooth bleaching. The changes in laser-induced fluorescence (∆LIF) were assessed using Raman spectrometry. Tooth color and autofluorescence data were obtained using quantitative light-induced fluorescence (QLF) technology. Pearson correlation analyses were used to confirm the relationship between ∆LIF and autofluorescence. Intraclass correlation coefficients (ICC) were calculated to compare the conventional and new prediction models. Decision tree analysis was performed to evaluate clinical applicability. RESULTS: The yellowness-to-blueness value from fluorescence imaging showed a moderate correlation with ∆LIF (r= -0.409, p = 0.001). The degree of agreement between the actual efficacy and that predicted by our novel model was high (ICC=0.933, p = 0.002). Decision tree analysis suggested that tooth autofluorescence could be a key factor in prediction of tooth bleaching outcomes. CONCLUSIONS: Our findings showed that autofluorescence detected from QLF images may be used to predict tooth bleaching efficacy. Our proposed model appeared to improve the predictability of tooth bleaching.

Evaluation of wound dehiscence after vertical bone graft by using quantitative light-induced fluorescence.

Wound dehiscence is a common complication following vertical bone augmentation of implant dentistry. If the implanted titanium mesh becomes exposed, the exposed titanium mesh should be removed with the contaminated grafts before a clinical graft infection develops. However, no generally accepted evaluation methods have been suggested to determine the removal timing or the extent of contaminated bone grafts to be removed. Quantitative light-induced fluorescence (QLF) technology has been used for various oral bacterial condition such as dental caries, plaque, peri-implantitis, and osteomyelitis. This paper reports two patients with wound dehiscence within the third week after vertical bone augmentation with autogenous particulate bone on the posterior maxilla. With conservative treatment, a QLF technology was applied to determine whether to remove the mesh. The exposed mesh of the first patient was removed when red-fluorescence was observed the red fluorescence by QLF. However, the other case did not show red fluorescence during the fifth week after dehiscence, and secondary healing was achieved without complications. The remaining bone grafts were well integrated into the sound cortico-cancellous complex sufficient to support the dental implant. Based on these clinical, radiological, and histological results, we discussed the rationale of QLF application on wound dehiscence after the bone graft in implant dentistry.

Effect of nicotine on orthodontic tooth movement and bone remodeling in rats.

OBJECTIVE: To quantitatively analyze the effect of nicotine on orthodontic tooth movement (OTM) and bone remodeling in rats using micro-computed tomography and tartrate-resistant acid phosphatase immunostaining. METHODS: Thirty-nine adult male Sprague-Dawley rats were randomized into three groups: group A, 0.5 mL normal saline (n = 9, 3 per 3, 7, and 14 days); group B, 0.83 mg/kg nicotine (n = 15, 5 per 3, 7, and 14 days); and group C, 1.67 mg/kg nicotine (n = 15, 5 per 3, 7, and 14 days). Each animal received daily intraperitoneal injections of nicotine/saline from the day of insertion of identical 30-g orthodontic force delivery systems. A 5-mm nickel-titanium closed-coil spring was applied between the left maxillary first molar (M1) and the two splinted incisors. The rate of OTM and volumetric bone changes were measured using micro-computed tomography. Osteoclasts were counted on the mesial alveolar bone surface of the distobuccal root of M1. Six dependent outcome variables, including the intermolar distance, bone volume fraction, bone mineral density, trabecular thickness, trabecular volume, and osteoclast number, were summarized using simple descriptive statistics. Nonparametric Kruskal-Wallis tests were used to evaluate differences among groups at 3, 7, and 14 days of OTM. RESULTS: All six dependent outcome variables showed no statistically significant among group-differences at 3, 7, and 14 days. CONCLUSIONS: The findings of this study suggest that nicotine does not affect OTM and bone remodeling, although fluctuations during the different stages of OTM in the nicotine groups should be elucidated in further prospective studies.

Effect of antimicrobial photodynamic therapy with Chlorella and Curcuma extract on Streptococcus mutans biofilms.

BACKGROUND: Antimicrobial photodynamic therapy (aPDT) using natural photosensitive agents is an effective method for preventing oral diseases of bacterial origin. The purpose of this study was to evaluate the antimicrobial effect of aPDT, using powdered extracts of Chlorella and Curcuma, on the biofilms of Streptococcus mutans (S. mutans), a bacterium that is known to cause dental caries. METHODS: Commercially available powdered Chlorella and Curcuma extracts were used as photosensitizers. S. mutans, cultured for 2 days, was inoculated (0.1 ml; 1 × 109 CFU/ml) on the surface of a hydroxyapatite (HA) disc and incubated for 24 h to allow the formation of a biofilm. The HA disc with the S. mutans biofilm was immersed in either Curcuma extract (0.5 mg/ml), Chlorella extract, distilled water (negative control), or Listerine (positive control) for 1 min and then irradiated with an LED (Qraycam; wavelength, 405 nm; energy, 59 mW) for 5 min. RESULTS: The application of aPDT with Curcuma or Chlorella extract to S. mutans 24-hour biofilms significantly decreased the number of viable cells and the live/dead cell ratio when compared with those in the negative control (distilled water; p < 0.05). CONCLUSIONS: aPDT using 405 nm light and Chlorella or Curcuma as a photosensitizer has significant antimicrobial effects against S. mutans biofilms. Thus, employing aPDT with natural plant extracts as photosensitizers could be an effective strategy for preventing dental caries but needs to be evaluated in properly controlled clinical trials..

Dental and Dental Hygiene Students' Knowledge and Perception on Fluoride Use in Dentistry.

AIM: The 75th anniversary of community water fluoridation in the United States was celebrated in 2020. However, there are studies that stimulate polarized discussion over the use of fluoride in dentistry. The purpose of this study was to evaluate dental and dental hygiene students' knowledge and perception of fluoride use in dentistry. MATERIALS AND METHODS: A survey was conducted to gauge participant's knowledge and perception of fluoride and their opinion on the need for developing viable alternatives to fluoride. An Institutional Review Board (IRB# 5190496) application was filed and approved. A hard copy survey was distributed to all student classes at Loma Linda University School of Dentistry (U.S.) between January 13, 2020, and February 5, 2020. Descriptive data were compiled and analyzed. Knowledge-based questions were compared using Kruskal-Wallis procedure to evaluate correct percentage among different classes. Perception questions were analyzed using a Likert scale and also a Chi-squared test. All tests were two-sided with α at 0.05. RESULTS: Out of 482 students, 282 students responded (58.5%). The mean of correct responses for knowledge ranged from 49 to 69%. There was a statistically significant difference among the classes. Overall the perception of the use of fluoride in dentistry was positive, and it changed with exposure to lectures on fluoride over the years. CONCLUSION: There was a correlation between knowledge and the perception of the use of fluoride in dentistry, indicating the importance of adequate delivery of didactic teaching on knowledge of fluoride to dental and dental hygiene students. CLINICAL SIGNIFICANCE: The oral healthcare provider plays a pivotal role in communicating pertinent information on the benefits of fluoride in preventing dental caries to the general public, prompting adequate delivery of didactic teaching on this topic in dental education.

Optical detection of the potential for tooth discoloration from children's beverages by quantitative light-induced fluorescence technology.

BACKGROUND: Some beverages are known to cause extrinsic staining on the tooth. This study investigated the degree of pigmentation caused by children's acidic beverages, and to confirm the possibility of the quantitative light-induced fluorescence (QLF) technology in assessing staining of the tooth. METHODS: Bovine tooth specimens were subjected to an 8-day pH-cycling model, using six children's beverages (experimental groups) and a cola (control group), and a remineralizing solution. Before and after the pH-cycling, white-light and fluorescence images of the enamel surface were photographed with a QLF to evaluate color change (ΔEafter) and fluorescence loss (ΔFafter), respectively. Paired t-test was used to compare the tooth colors obtained before and after the pH-cycling. Spearman correlation analysis was performed to examine the correlation between the ΔEafter and ΔFafter values. RESULTS: Median ΔEafter values of all the beverages ranged from 1.33 to 20.42, showing the greatest value in Koal-Koal Koala™ (KKK, p < 0.001). The ΔEafter was correlated with ΔFafter value negatively (ρ=-0.611, p < 0.001). The median ΔFafter varied by beverages (-38.86-0.00) and KKK caused the greatest value. CONCLUSIONS: The cola and 6 children's beverages showed the possibility for discoloration on the tooth. The QLF technology may enable monitoring the discoloration induced on the tooth surface by acidic beverage.

Simple oral exercise with chewing gum for improving oral function in older adults.

BACKGROUND: As general and oral health are closely interrelated, promoting oral health may extend a healthy life expectancy. AIMS: To evaluate the long-term effects of simple oral exercise (SOE) and chewing gum exercise on mastication, salivation, and swallowing function in adults aged ≥ 65 years. METHODS: Ninety-six participants were assigned to control, SOE, and GOE (chewing gum exercise with SOE) groups. The SOE comprised exercises to improve mastication, salivation, and swallowing function. Control group participants performed no exercises. The intervention period was 8 weeks, followed by a 3-week maintenance period. The Mixing Ability Index (MAI), occlusal force, unstimulated saliva, and repetitive saliva swallowing test were evaluated at baseline and 2, 5, 8, and 11 weeks later. Self-reported discomfort was re-evaluated after 8 weeks. RESULTS: After 8 weeks, mean MAI differences from baseline significantly increased in both groups; the increase in the GOE group was largest and four times higher than in the control group. Mean differences of occlusal force from baseline increased by 56 N (SOE group) and 60 N (GOE group). The increase of salivation was greater in the SOE (3.6-fold) and GOE (2.2-fold) groups than in the control group. Furthermore, 27% and 18% of SOE and GOE group participants, respectively, were re-categorized as having good swallowing function. Participants reported less discomfort as oral functions improved. DISCUSSION: These findings may facilitate the development of clinical practice guidelines for optimal oral care in older adults. CONCLUSION: While both SOE and GOE may improve oral function in older adults, GOE is recommended for those with impaired mastication. TRIAL REGISTRATION: KCT0003305, retrospectively registered 31/10/2018.

Age, period and cohort trends in oral health status in South Korean adults.

OBJECTIVES: The purpose of this study was to identify the age, period and cohort effects on the changes in oral health status in South Koreans. METHODS: The age, period and cohort analysis (APC analysis) of the oral health status was conducted using an aggregated age-by-time period table. The age-by-time period table was formulated using data from the Korea National Oral Health Survey (KNOHS) 2000 and 2006, and the Korea National Health and Nutrition Examination Survey (KNHANES) 2010 and 2015. Two oral health outcomes were measured: the number of teeth and Decayed-Missing-Filled Teeth (DMFT) index. Descriptive analysis by graphical representation and partial least square (PLS) regression was used for APC analysis. RESULTS: Both graphical description and PLS regression showed age and cohort effects in oral health status with the number of teeth decreasing and the DMFT index increasing with age. No period effects were found in either index. The number of teeth increased in the recent birth cohorts. However, the DMFT index showed a reverse J-shaped trend, which worsened in recent birth cohorts. The DMFT index increase in the recent cohort was mainly attributed by an increase in the FT index. CONCLUSIONS: The effects of age on the number of teeth and caries highlight the importance of oral health in adulthood. The increased caries experience in recent cohorts may indicate the limitations of the current oral health policy. It would be relevant to explore what determinants cause the changes in oral health status. Future oral health policies should address the new directions to reduce the burden of oral diseases.

Detection of dentin-exposed occlusal/incisal tooth wear using quantitative light-induced fluorescence technology.

OBJECTIVES: To prolong tooth life expectancy, tooth wear resulting in dentin exposure should be detected early. However, the most objective methods are clinically limited. We validated fluorescence parameters for distinguishing enamel from dentin-exposed wear in clinical images. METHODS: Quantitative light-induced fluorescence (QLF) images of 73 adults (age range: 22-48 years, mean: 33.81 ±â€¯7.71 years), including 1949 teeth with varying tooth wear degrees, without restorations, caries, or cusp area fractures, were used to calculate the ΔFwear values. Areas-of-interest (AOIs) were selected from QLF images; the ΔFwear values and the tooth wear index (TWI) were calculated for each tooth. The ΔFwear values were compared according to the TWI scores. The optimum ΔFwear values for distinguishing enamel and dentin-exposed wear were determined using the receiver operating characteristic (ROC) curve analysis. RESULTS: Overall, 1949 AOIs were evaluated. The median ΔFwear values for teeth with TWI scores 0, 1, and 2 (5.7 %, 10.3 %, and 17.0 %) differed significantly (P < 0.001). The optimum cutoff ΔFwear values were 12.1 and 14.7 in the anterior and posterior teeth, respectively; the corresponding areas under the ROC values (AUROCs) were 0.86 and 0.93 (sensitivity: 0.79 and 0.85; specificity: 0.79 and 0.85, respectively). The ΔFwear cutoff values for different age groups were within a range (12.7-13.7) and showed high validity (sensitivity, specificity, and AUROC: 0.78, 0.77-0.78, and 0.87-0.88, respectively). CONCLUSIONS: At the optimum threshold, the ΔFwear values showed high validity for distinguishing dentin exposure in worn teeth (AUROC: 0.87‒0.93) and could determine pathological tooth wear, particularly in posterior teeth. CLINICAL SIGNIFICANCE: We demonstrated the feasibility of using QLF to detect dentin-exposed tooth wear and present optimal thresholds according to age. In addition, we confirmed the possibility using such image data for objective and cost-effective epidemiological investigation and application in tele-dentistry.

Quantitative light-induced fluorescence as a potential tool for detection of enamel chemical composition.

BACKGROUND: Little is known about how the chemical composition of enamel affects the optical properties of teeth, but advances in technology allow this to be studied using white-light and fluorescent images. This study aimed to identify the variation in enamel chemical composition that may affect tooth optical properties, such as tooth color and autofluorescence. METHODS: Sixty-one specimens of extracted human molars were prepared. Raman spectrometry was used to assess chemical composition of enamel, and tooth color, and autofluorescence from enamel were evaluated by quantitative light-induced fluorescence (QLF) images. Pearson correlation and multiple linear regression analyses were used. RESULTS: Enamel fluorescence was related to enamel composition rather than tooth color. The b* value from the fluorescence image had a moderate correlation with crystallinity (full-width at half-maximum: r = -0.433, p < 0.001) and laser-induced fluorescence intensity (r = 0.450, p < 0.001) from Raman spectroscopy. In multiple linear regression analysis, the chemical composition of the tooth had a significant effect on the b* value from the fluorescent image (R2 = 0.433, p < 0.001). In contrast, tooth color values (L*, a*, and b*) were not correlated with chemical composition. CONCLUSIONS: The present study revealed that enamel autofluorescence in QLF was related to chemical composition of the enamel, particularly the inorganic‒organic interface. While enamel chemical composition can be detected only in a laboratory environment, enamel fluorescence by QLF may enable estimation in a dental clinic, which has implications for the field of tooth bleaching or esthetic restorative materials.

Clinical assessment of an automated fluorescent plaque index scoring with quantitative light-induced fluorescence.

OBJECTIVE: The aims of this study were to evaluate the clinical applicability of a new fluorescent plaque index scoring (FPI) with the Turesky modified Quigley-Hein plaque index (mQH) and to evaluate its relationship with plaque maturity. METHODS: In total 69 subjects participated in this study. White-light and fluorescent images of anterior teeth were acquired using a Qraycam (AIOBIO, Seoul, Korea). FPI was obtained from fluorescent images using the proprietary software (Q-Ray v.1.39, Inspektor Research System BV, Amsterdam, The Netherlands). Teeth were stained with a two-tone disclosing agent. mQH was used to manually score the combined red and blue disclosed plaque (Combi-mQH) and blue disclosed plaque (Blue-mQH) with the white-light images. Linear relationships between FPI and Combi-mQH (or Blue-mQH) were evaluated by using simple linear regression analysis. Differences of Combi-mQH (or Blue-mQH) with respect to FPI scores were statistically evaluated by using ANOVA with Duncan post hoc correction. RESULTS: FPI showed a moderate positive correlation with Combi-mQH (r = 0.66, P < 0.001) and a high positive correlation with Blue-mQH (r = 0.78, P < 0.001). The model explanatory power (R2) between FPI and Blue-mQH was 60.8 %, which is 16.8 % higher than the explanatory power observed with Combi-mQH (44.0 %). Both Combi-mQH and Blue-mQH increased significantly with increasing FPI score (P < 0.001). CONCLUSION: In this study we found that the FPI scoring system can be used to detect plaque and quantitatively distinguish plaque levels. In addition, FPI was determined to be useful in clinic because of its ability to detect and distinguish old and mature plaque.