Machine learning (ML) algorithms play a key role in estimating dental age. In this study, three ML models were used for dental age estimation, based on different preprocessing methods.The seven mandibular teeth on the digital panorama were measured and evaluated according to the Cameriere and the Demirjian method, respectively. Correlation data were used for decision tree (DT), Bayesian ridge regression (BRR), k-nearest neighbors (KNN) models for dental age estimation. An accuracy comparison was made among different methods.2), mean error (ME), root mean square error (RMSE), mean square error (MSE) and mean absolute error (MAE), the above five metrics were used to evaluate the accuracy of age estimation.We analyzed 748 orthopantomographs  from eastern China between the age of 5 and 13 years in this retrospective study. Three models, DT, BRR, and KNN, were used to estimate the dental age. The data in ML is obtained according to the Cameriere method and the Demirjian method. Coefficient of determination (R2 = 0.94).Our experimental results showed that the prediction accuracy of dental age was affected by ML algorithms. MD, MAD, MSE, RMSE of the dental age predicted by ML were significantly decreased. Among all the methods, the KNN model based on the Cameriere method had the highest accuracy (ME = 0.015, MAE = 0.473, MSE = 0.340, RMSE = 0.583, RThe results show that the prediction accuracy of dental age is influenced by ML algorithms and preprocessing method. The KNN model based on the Cameriere method was able to infer dental age more accurately in a clinical setting. Age estimation through the application of dental morphology and radiology plays an important role in clinical medicine and forensic medicine –3. Age cThe Demirjian method classifies the teeth into eight stages from A to H depending on maturity and calcification . The sumBoth of these methods have been applied in China. The study by Ye et al.  showed tMachine learning (ML) methods are widely used for early prediction and identification of different types of diseases –14. We aThe advent of ML has further reduced the error in age estimation and made age estimation more reliable and practical. Many studies have applied ML to the estimation of bone age , and theThe purpose of this study is to compare (1) the dental age prediction ability of Demirjian and Cameriere methods by ML algorithm (2) the dental age prediction ability of 3 ML algorithms: decision tree (DT), Bayesian ridge regression (BRR), k-nearest neighbors (KNN) model.The research was authorized by the Independent Ethics Committee of the Shanghai Ninth Hospital affiliated with Shanghai Jiao Tong University, School of Medicine (2017-282-T212). All methods were performed in accordance with relevant guidelines and regulations. Informed consent was obtained from all subjects or their legal guardian(s) participating in the study.This retrospective study selected digital panoramic radiographs taken by KODAK 8000C Panoramic and Cephalometric Digital Dental X-ray Machine collected during outpatient treatment between 2000 and 2013. A total of 748 panoramic images of adolescents aged 5–13, including 356 females and 392 males, were included in this study. Their age and gender distributions are shown in The inclusion criteria for panoramic radiographs are as follows: complete mandibular permanent teeth (except third molars); clearly visible root development; no systemic disease; no history of root canal therapy; no related diseases affecting mandibular development, such as cysts or cancer.Digital panoramic radiographs were stored on a computer and processed by computer-aided measuring software (Adobe Photoshop CC 2017). All panoramic slices were pre-processed according to the Cameriere and Demirjian methods, and the relevant data were recorded.According to the Demirjian method, 7 mandibular teeth were classified into eight stages from A to H according to their development and mineralization  Figure , left. Wi, i = 1, ..., 7) between the inner sides of the open apex of each of the seven left mandibular teeth by the length of the tooth  to obtain the normalized value . Xi  = 0 if tooth development is complete and the apical foramen is closed  of the seven permanent teeth and the gender of the sample were included into the ML algorithm as variables, when it comes to Cameriere method.The Cameriere method, in short, divides the distance , the sum of the normalized open apices , the number of teeth with complete root development (N0) and the first-order relationship between s and N0 (s·N0). The target value was the chronological age.The following ML supervised regression algorithms were tested, DT, BRR and KNN model. Out-of-sample performance have been assessed by means of the well-known K-fold cross-validation. More precisely, in this study, we divided the data into ten groups. The image data were divided into 10 groups, 9 groups are used as training data and one for validation , 20. ThiAll three ML algorithms are supervised learning. DT is a supervised learning methodology commonly adopted for both classification and regression . Ridge rThe KNN algorithm is supervised learning, where each piece of data in the training sample set has a definite known label. KNN does not have an explicit learning process and is, in fact, a well-known representative of lazy learning. The KNN algorithm itself is simple, easy to understand and implement, and it is highly accurate and insensitive to outliers , 24. TheTo avoid overfitting, a 20% validation dataset was used during hyperparameter optimization. The tuning of the hyperparameters to obtain the best model was achieved by exploring multiple combinations using the GridSearchCV function. The hyperparameters described in The method of age inference may underestimate or overestimate age, which is known as prediction error. An accurate method has low prediction error according to some performance metric, meaning that the average difference between dental age and chronological age will be close to zero. Accuracy refers to how large the difference between the dental age (DA) and chronological age (CA). The difference between DA and CA can be expressed in many ways according to the considered performance metric, such as mean absolute error, median absolute error, etc.2), root mean square error (RMSE) and mean square error (MSE) were also used to evaluate the accuracy of age estimation.The chronological age of each subject was calculated by subtracting the date of birth from the date the panoramic was taken. In this study, the mean error (ME) of dental age and chronological age was calculated to quantify the direction of error (CA-DA), where positive values indicate that dental age is underestimated and negative values conversely. The mean absolute difference (MAD) of dental age and chronological age was calculated to quantify the magnitude of the error. In addition to the above two metrics, three other indicators were used to asses accuracy, the coefficient of determination , Pycharm 2021 and Python 3.8.2. The significance level was set at 5%.Since the possibility of reliably replication measurements is an important component of any measurement study, both intra- and interobserver error was tested. Both observers participating in the study were trained in age estimation methods. Each observer assessed each of the 748 radiographs. To assess interobserver reliability, both observers twice evaluated 50 randomly selected X-rays before starting the original study. The intraobserver correlation coefficient (ICC) for the intra-observer agreement was 0.92 for both observers, whereas it was 0.86(for Cameriere method) and 0.82(for Deimirjian method) for the inter-observer agreement. The results of the intra-class correlation coefficient show the inter-observer and test-recovery reliability.A total of 748 panoramic images, 356 females and 392 males, were included in this study. The distribution of males and females in each group was relatively even. The performance metrics are shown in Compared with traditional methods, whether it is Deimirjian or Cameriere method, ME, MAE, MSE and RMSE have been greatly reduced after the optimization of ML, which means that the accuracy is greatly improved. When using the traditional Deimirjian method, its ME and MAE were −0.647 and 0.982, respectively, and the MSE and RMSE were 22.254 and 4.717. That is, the dental age estimated by the traditional Deimirjian method was 0.647 year higher than the chronological age, with an error of 0.982 year. With the aid of ML, the ME of the three models  were −0.002, 0.011 and −0.027, respectively. The MAE also dropped to 0.510, 0.523, and 0.517. ML also had obvious advantages in the Cameriere method. Before using ML, the ME and MAE of the Cameriere method were 0.592 and 0.846, respectively. After optimization with ML, the ME became −0.030 (BRR), 0.052 (DT) and −0.015 (KNN), and the MAE dropped to 0.535 (BRR), 0.584 (DT) and 0.473 (KNN).2 (0.940) and the smallest ME and MAE. The DT model had the lowest R2 (0.893), that was, the lowest fit. In the Deimirjian method, the DT model was also a ML model with the lowest fitting degree (R2 = 0.892). The best performer in the Deimirjian method was the BRR model , followed by the KNN model   .Among all the methods in this study, the smallest MAE is the KNN model ML based on the Cameriere method (MAE = 0.473), the dental age is only overestimated by 0.015 years, which is close to 0. The fit was also very high, at 0.94.The linear equation was used to estimate the absolute error of the dependence of the sample population on the dental age under different methods . Errors δ, more individuals will be covered. In δ, whereas the red area corresponds to the interval DA ± 2δ. The δ was approximated as linear function of absolute error in dependency of dental age. This means that the independent variable of δ was the dental age and the dependent variable was the corresponding absolute error.As can be seen from In addition, correlation coefficients were calculated for the respective variables of the Cameriere and Demirjian methods. The heat map of the correlation coefficients is shown in In oral forensics, the need to infer the age of life becomes increasingly important as more immigrants  come to a country without a valid legal identity document. Second, missing or uncertain birth data is also common. For these reasons, more and more studies have been conducted on the estimation of dental age.In other studies on the Cameriere's European formula, children in Bosnia-Herzegovina overestimated the dental age of girls by 0.10 year and underestimated the dental age of boys by 0.02 year ; the denTake a look at Demirjian in use around the world. A study by Jayaraman et al.  showed tA study by Gaur et al.  showed tThe inclusion of ML can substantially improve the accuracy of age inference. Among the three ML algorithms in this study, the DT model performed the worst. Perhaps this is because age estimation is a regression problem rather than a binary classification problem. Therefore, regression models (such as KNN in this study) are more suitable for age estimation. In the study of Galibourg et al. , KNN alsConvolutional neural network (CNN) is part of deep learning, a new research direction in machine learning that is more complex and specialized. A study by Zaborowicz et al.  showed tThis is the first comparison of the accuracy of the Cameriere and Demirjian methods of dental age estimation using ML simultaneously. The ML demonstrated its excellent performance, with very low MAE, ME MSE and RMSE in dental age. We believe that this breakthrough will significantly increase the feasibility of clinical dental age estimation. ML algorithm helps to establish assessment criteria and improve the accuracy of dental age estimates in local populations.The present study provides a reference for future clinical applications of dental age, such as the assessment of child development and the projection of the age of the missing population. The sample for this experiment was drawn from hospitals in eastern China, filling a gap in machine learning for dental age inference in that region. This further increases the potential for global clinical application of dental age. Of course, this study still has geographical limitations, the data from other regions were not collected, which needs to be further confirmed in subsequent experiments. Individual differences caused by developmental differences and nutritional dietary habits of different ethnic groups are inevitable in the extrapolation of dental age. Perhaps including samples from more regions in the ML could reduce such errors. In addition, further research is needed to develop models regarding fully automated dental age inference. We believe that as the sample size increases, the accuracy of machine learning will further improve.2 = 0.94).In this study, ML was shown to greatly improve the accuracy of dental age inference. It was shown that the accuracy of dental age inference was higher than that of the traditional Demirjian method or Cameriere European formula, for both KNN, DT and BRR models. The highest accuracy among the machine learning dental age inference based on preprocessing of different methods was the KNN model based on the Cameriere method . Written informed consent to participate in this study was provided by the participants' legal guardian/next of kin.SS: methodology and writing original draft. XY: investigation and resources. JW and LF: methodology and formal analysis. JZ and JT: conceptualization, supervision, and project administration. All authors have read and approved the final manuscript.This work was sponsored by the Interdisciplinary Program of Shanghai Jiao Tong University (YG2019ZDA07), Innovative Research Team of High-Level Local Universities in Shanghai (SHSMU-ZLCX20212401), and Shanghai Sailing Program (No. 21YF1424100).The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.All claims expressed in this article are solely those of the authors and do not necessarily represent those of their affiliated organizations, or those of the publisher, the editors and the reviewers. Any product that may be evaluated in this article, or claim that may be made by its manufacturer, is not guaranteed or endorsed by the publisher.


MD was associated with the emotional exhaustion dimension of burnout. Spirituality and/or religiousness was shown to be a moderating variable. Further research is needed to deepen our understanding of the correlation between MD and burnout and the role of spirituality and/or religiousness as moderators.Moral distress (MD) in healthcare providers is widely recognized as a serious issue in critical care contexts. It has the potential to have negative impacts on both personal and professional wellbeing, the quality of care provided and staff turnover. The aim of this study was to investigate the relationship between MD and burnout among neonatal intensive care unit (NICU) healthcare professionals and identify the possible factors associated with its occurrence. Participants were asked to complete an online survey, which covered sociodemographic and professional information and included two self-report questionnaires . The sample comprised 115 healthcare providers  working in four NICUs located within the province of Turin, Italy. The results revealed overall low levels of MD, with no significant differences between nurses/physiotherapists and physicians. Nurses/physiotherapists showed a statistically significant higher percentage of personal accomplishment burnout (32.9%) compared with physicians (8.6%;  Moral distress (MD) concerns the distress associated with the moral integrity of a person. Its construct was first theorized in the 1980s by Jameton ,3. SinceMD can have many consequences and be experienced from different perspectives. It can have negative impacts on both personal and professional life spheres . ConsequBurnout is caused by excessive and prolonged stress, and it can be considered as a result of a disturbance of the equilibrium between the job demands individuals are exposed to and the resources they have at their disposal . It is cDue to the nature of careers in healthcare, and the high commitment levels required to work in clinical situations, especially in contexts characterized by high stress levels, it is not surprising that MD has been largely studied and detected in medical care scenarios . In factIntensive care units (ICUs) are medical care environments in which healthcare professionals are highly susceptible to experiencing MD due to the highly vulnerable nature of their patients, for whom every decision and action taken is of utmost importance. Disagreements between colleagues within an ICU are also likely to be highly charged, exacerbated by the necessity for timeliness, the appropriateness of intervention choices made, the responsibility for making end-of-life decisions and the uncertainty of treatment outcomes ,39,40. TStudies conducted in the context of NICUs have highlighted some demographic characteristics associated with the probability of experiencing MD. Although it is important to recognize that the risk of MD is a reality for all practitioners in the neonatal ward, it has been especially linked with nursing professions. This is probably a consequence of their perceived lack of power in making decisions and difficulties experienced in nurse–physician interprofessional relationships and teamwork . PreviouOther studies have shown a possible correlation between self-reported levels of religiousness and spirituality in healthcare professionals and the experiencing of MD, but the results published on this aspect to date remain unclear and controversial ,35,44,45In the Italian context, a limited number of studies have explored MD among healthcare professionals ,52,53,54The sample of this cross-sectional study was composed of healthcare providers working in any one of the four NICUs operating within the province of Turin, Italy . Participants were eligible for inclusion if they worked as physicians, nurses, physiotherapists or healthcare assistants in one of the aforementioned NICUs. Those who did not provide their consent were excluded from the study. Healthcare providers were recruited from December 2021 to February 2022 through an email sent to their institutional email address which invited them to participate in the electronic survey set on the Google Forms platform. The study was conducted in accordance with the Declaration of Helsinki, and the research protocol was approved by the Ethics Committee of the University of Turin. Informed consent was obtained by asking all participants to click a button at the beginning of the online survey consenting to their participation. Participation was voluntary and anonymous, and participants received no compensation.The online survey took about 15 min to complete and was composed of two sections. The first included questions about sociodemographic factors , professional information , and data about their religious and spiritual orientation. Regarding the latter, as religion and spirituality are not mutually exclusive but possess overlapping as well as distinct elements , we askeThe Italian Moral Distress Scale-Revised (MDS-R) , a 14-itThe Maslach Burnout Inventory (MBI) , a 22-itThe second section comprised two validated self-report questionnaires:p < 0.05. All statistical analyses were performed using R version 4.1.2 .Continuous variables were expressed as the median plus interquartile range (IQR), and groups were compared using the Mann–Whitney U test. Categorical variables were summarized as counts and percentages, and the χ2 test or Fisher’s test was performed, as appropriate, to test for differences between groups. A univariate analysis based on a linear regression model was carried out to identify associations between sociodemographic variables and MDS-R, MBI-EE, MBI-DP and MBI-PA. Coefficients and 95% confidence intervals (95% CIs) were reported. A final multivariate model was developed based on statistical selection procedures. Model selection was performed using an automatic approach based on the Akaike information criterion (AIC) method. Given the large number of covariates, a genetic algorithm was employed to explore the candidate set of models. The significance level was set at A total of 197 healthcare providers were asked to participate in the online survey; 115 questionnaires were collected, giving a response rate of 58.4%. Sample characteristics, summarized as percentages, are shown in p = 0.012).MDS-R total scores ranged from 0.2 to 13 for nurses/physiotherapists, with a median score of 4.36 (IQR: 2.39–5.64); for physicians it ranged from 1.7 to 10, with a median score of 3.36 (IQR: 2.68–4.11) . No signInitial univariate analyses of the relationship between demographic variables and the MDS-R score indicated no statistically significant association with the professional category, other sociodemographic variables, professional experience or spirituality with moral distress or burnout .p = 0.001) in individuals with a comparable spirituality rating and MBI-DP , 0.29 (p = 0.002) and –0.18 (p = 0.051), respectively.To the best of our knowledge, this study is the first to investigate moral distress and burnout in healthcare providers working in Italian NICUs. As highlighted in previous research, healthcare professionals working in NICU settings may be at a higher risk of developing MD than in other hospital departments, which may in turn have negative effects on both personal and professional wellbeing, as well as significant repercussions on patient care ,41.This study sample reported overall low levels of MD in healthcare professionals from the four NICUs located in Northern Italy. MDS-R scores were slightly lower in physicians than in nurses/physiotherapists, although the difference was not significant. Although this result contrasts with that of some studies which found higher MD levels in nurses than in other professional categories ,53,54,59p = 0.962). There was a non-significant trend for high DP to be more prevalent in nurses/physiotherapists compared with physicians , and a very significant trend for low PA in the former vs. the latter . Previous studies investigating burnout dimensions in pediatric healthcare professionals showed its development to be multidimensional and largely influenced by personal, professional and organizational/contextual factors [The prevalence of the three underlying burnout dimensions in our sample  was similar to that reported in a recent meta-analysis on pediatric nurses  . The com factors ,64,65, w factors ,67. A lo factors . With th factors , few stu factors . Conside factors .The results of our study revealed a correlation between MD and burnout levels, corroborating the results of numerous other studies from an array of healthcare contexts ,74,75,76The present study revealed a significant association between MD and EE moderated by spirituality and/or religiousness. In fact, the association between EE and MD was significantly weaker among religious and/or spiritual individuals as compared with those who considered themselves non-religious and non-spiritual. Individual spiritual and religious beliefs can have an impact on the perception of MD . One stuThe main strengths of this study are that it investigated MD together with all three dimensions of burnout, and revealed a significant role of spirituality/religiosity as one of the potential moderating effects of the MD–burnout relationship. The study also has a number of limitations. First, due it its cross-sectional design, only associations between the variables studied can be detected, precluding definitive conclusions regarding the direction of causality. Second, the generalizability of our findings is limited by the respondents’ self-selection of responses, the lack of data on non-responders, the limited number of NICU healthcare providers participating in the study and the restricted geographical area in which these four NICUs are located. Third, data regarding gender were not collected in order to ensure the anonymity of the participants. Future multicenter studies with larger sample sizes are needed to deepen our understanding of MD and burnout among NICU healthcare providers, particularly in the Italian context, as the results would help identify strategies to alleviate both MD and burnout.Future studies might also consider using a pediatric-specific instrument for MD , pendinIn conclusion, this study revealed an association between MD levels in NICU healthcare providers and levels of burnout, in particular the EE dimension; this relationship was also shown to be moderated by spirituality/religiousness. Further research is needed to fully explore the role of religious beliefs and spiritual well-being on MD and burnout whilst bearing in mind the possible influence of different sociocultural components.


Among juniors, it was significantly indicated by the composite physical summary , PSS , and number of social supports . The factors associated with quality of life differed between seniors and juniors. Universities must provide opportunities for students to find more friends, especially for juniors who have limited socialization opportunities owing to the pandemic.Owing to the COVID-19 pandemic, classes and club activities in Japanese universities have been canceled; this may increase students' perceived stress and adversely affect their quality of life. This study investigated the factors that influence Japanese university students' quality of life during the pandemic. An online questionnaire collating data related to demographic characteristics, the perceived stress scale (PSS), sense of coherence (SOC), number of social supports, and quality of life  was distributed to university students. Participants were divided into two groups: those who entered university before (seniors) and after (juniors) the onset of the pandemic. Their scores on the two sub-domains  of the SF-8 were evaluated. Multiple regression analysis was performed to identify factors associated with the composite mental summary of the SF-8. Regression analysis indicated that the predictor model of the composite mental summary differed between juniors and seniors. Among seniors, the composite mental summary was significantly indicated by the composite physical summary (β = 0.549,  The ongoing coronavirus (COVID-19) pandemic is yet to be contained, even 2 years after its outset. Japan banned inbound travel from late January 2020 to control the outbreak of the virus. Travel restrictions led to the cancellation of job fairs for university students . Similar to the reports on university students in Croatia . The SF-8 questionnaire is a shorter version of the SF-36 health survey tool used as a practical measure of health-related QoL  and dependent variables . Cronbach's alpha confirmed internal consistency.IBM SPSS Statistics Version 25-J was used to calculate descriptive statistics for the participants' general characteristics. Bivariate analysis was conducted by performing chi-square tests and p < 0.05.Multiple regression analysis was conducted to identify the factors associated with mental health-related QoL. The variance inflation factor (VIF) was used to quantify the severity of multicollinearity (1.01 < VIF < 1.22). The level of statistical significance was set at Informed consent was obtained from the students online prior to their participation in the survey. Ethics approval for this study was granted by the Biomedical Sciences Ethics Board of Nagasaki University (No. 21092401).A total of 1,982 e-mails were sent to the students, of which 314 were answered. Eleven incomplete responses were excluded from the analysis. Thus, responses from 303 students  were analyzed (response rate: 15.3%). Regarding academic department, 223 (73.6%) students were non-medical science majors, and 80 (26.4%) were medical science majors.The mean PSS score (Range: 3–40) was 20.86 (SD = 6.59). The average number of social supports (Range = 17–60) was 46.22 (SD = 8.81). The average SOC score (Range = 7–21) was 15.5 (SD = 2.9), and Cronbach's alpha was 0.70. The average composite physical summary score was 8.34 (SD = 3.66), with a Cronbach's alpha of 0.78 and a range of 4–22. The average score was 9.39 (SD = 3.76) for the composite mental summary, Cronbach's alpha was 0.76, and the range was 4–20.r = 0.668, p < 0.001), followed by the PSS , and number of social supports . The composite mental summary scores of the seniors showed a stronger correlation with their composite physical summary scores , followed by the PSS scores , SOC scores , and number of social supports , going out together (p = 0.008), and teaching each other what they did not understand (p = 0.041).The characteristics of the respondents by grade group are presented in p < 0.001) and seniors . The PSS scores, which were positively correlated with the composite mental summary scores in both juniors  and seniors , were the next strongest. Furthermore, there was a negative correlation between the composite mental summary scores and the number of social supports  among the juniors, indicating that the greater the number of social supports, the higher they scored on the composite mental summary. However, such a tendency was not observed among senior students (students .The present study clarified the factors that determined the mental health-related QoL of junior and senior students at a Japanese university. Notably, there was no significant difference in the mean composite mental summary score between the two grade groups.The composite physical summary and PSS scores were significantly associated with the composite mental summary among senior students. The composite mental summary score was significantly associated with composite physical summary, PSS scores and number of social support among juniors. This finding indicates that social support played a crucial role in determining the composite mental summary for junior students. Therefore, it was hypothesized that social support might act differently in predicting the mental health-related QoL by grade group. Although there were no significant differences between the mean scores of the number of social supports, junior students were more likely to solicit friends to talk to, go out together, and teach each other what they did not understand. This result suggests that even under the restricted socialization conditions due to COVID-19, junior students attempted to solicit social support more often than seniors by maximizing any socialization opportunities.Senior students had existing social support from peers and friends obtained before the pandemic's onset through regular face-to-face classes and club activities. In other words, in the case of senior students, existing social support was available whenever needed, and therefore, they did not need to acquire new sources of support. However, juniors needed to find social support independently by talking to other students in the classroom or developing the relationship further by going out together and exchanging necessary information to maintain a good QoL. These actions are successful coping strategies to survive the “new normal,” where everyone needs to adjust to daily life amid the pandemic.According to Antonovsly  theory, A few studies have previously indicated the association between academic year and mental health status during the COVID-19 pandemic. Ma et al.  found thThis study may be subject to sampling bias. Although the students learned to use information technology in high school and could easily access the online survey with their cellphones and digital devices, it is possible that some students felt anxious about accessing the survey and thus could not participate in the study.Nonetheless, the implications of this study are crucial for health policies that target university students in Japan, as most universities have no choice but to limit face-to-face lessons amidst the ongoing COVID-19 pandemic. The present findings indicate the need to develop an appropriate program to help students maintain a good QoL in the “new normal” era. As an essential source of social support for students, universities need to establish systems that can provide students the support needed to maintain their QoL. The following are some recommendations.To maintain good QoL, it is suggested that universities provide students, particularly juniors, opportunities to meet their peers and develop friendships easily. First, this increases the chances of making friends online and creates opportunities for virtual face-to-face relationships. Conducting online group discussions within a class may be a good opportunity for students to exchange their opinions, thereby understanding each other better. Second, when face-to-face lessons begin, class-based activities are expected to increase. Universities should also provide students with helpful information about COVID-19, which may help them avoid distracting information about the uncertainties regarding the pandemic.Such information and assistance should not be limited to college life, but it should also include the post-graduate period when they expect to be in employment. Currently, the global youth unemployment rate has increased, due to the recession caused by the COVID-19 crisis. Japan is not an exception. The Ministry of Health, Labor and Welfare reported that the employment rate of university graduates has dropped by 2% in fiscal year 2020 (Ministry of Health, Labor and Welfare, Moreover, cellphone and internet use (Kim et al., It is also suggested to utilize social support from other sources, such as family members. Because social support from family was associated with low levels of depression and PTSD symptoms of the university students (Liu et al., According to the Ministry of Education, Culture, Sports, Science, and Technology, as of June 5, 2020, 60% of universities nationwide provided online classes, while 30% offered online and face-to-face classes (Ministry of Education, Culture, Sports, Science and Technology, The raw data supporting the conclusions of this article will be made available by the corresponding author on reasonable request.The studies involving human participants were reviewed and approved by Biomedical Sciences Ethics Board of Nagasaki University. The patients/participants provided their written informed consent to participate in this study.RU, ST, and MD developed the questionnaire and conducted the analysis under the instruction of YH and KA. YH wrote the first draft of the manuscript. All authors contributed to the article and approved the submitted version.This study was funded by Management Expenses Grants, Nagasaki University.The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.All claims expressed in this article are solely those of the authors and do not necessarily represent those of their affiliated organizations, or those of the publisher, the editors and the reviewers. Any product that may be evaluated in this article, or claim that may be made by its manufacturer, is not guaranteed or endorsed by the publisher.


The efficacy of cap-assisted and water-exchange colonoscopy, individually or in combination for adenoma detection is well documented. Moreover, prone positioning colonoscopy may also improve adenoma detection by decreasing loop formation. However, the efficacy of triple-combination colonoscopy using the above methods for adenoma detection is unclear. This study aimed to compare the effectiveness of combining modified cap-assisted and water-exchange colonoscopy with prone position (CWP) and conventional colonoscopy (CC) for adenoma detection.A total of 746 patients who underwent either CWP or CC, performed by 2 board-certified gastroenterologists between December 2019 and March 2020, were investigated retrospectively. Cap-assisted colonoscopy was modified using hooking and dragging maneuver. We evaluated the polyp detection rate (PDR), adenoma detection rate (ADR), and the mean number of adenomas detected per procedure (MAP).P < .01; ADR: 70.1%, vs 49.2%, P < .01; proximal colon MAP: 1.24 vs 0.55, P < .01).There was no significant difference in sex, age, the indication of colonoscopy and quality of bowel preparation between the 2 groups. PDR, ADR, and proximal colon MAP were significantly higher in the CWP group than in the CC group (PDR: 84.9% vs 59.8%, CWP is more effective than CC for PDR, ADR, and proximal colon MAP. Although it may facilitate adenoma detection, further studies assessing the synergistic or complementary effects of combining these methods are needed. Screening for colorectal cancer using colonoscopy has several advantages, including highly sensitive detection, and a single-step diagnosis and treatment of cancer or precancerous lesions. In addition, several studies have reported the efficacy of screening colonoscopy in preventing the incidence and deaths from colorectal cancer.–6 However, despite the many advantages of screening colonoscopy, it has a drawback–detecting cancer and precancerous lesions using colonoscopy is operator dependent.,8Colorectal cancer is the third leading cause of new cancer cases and the second leading cause of cancer deaths worldwide.–11 Many studies have focused on the improvement of these quality indicators, and new techniques have been developed, such as cap-assisted colonoscopy, water-exchange colonoscopy, and a combination of the above 2 methods. Cap-assisted colonoscopy involves a transparent hood fitted to the tip of the colonoscope and allows better mucosal exposure, particularly in the regions behind the proximal aspect of the haustral folds; it also decreases the cecal intubation time. Water-exchange colonoscopy provides the advantage of additional cleansing and may aid in optimizing the mucosal examination.Among many quality indicators for monitoring operator dependency, the adenoma detection rate (ADR) and the mean number of adenomas detected per procedure (MAP) are the most sensitive indicators of the quality of colonoscopy. Thus, devising a method that can increase ADR and MAP without using complicated devices, such as Endocuff, Endocuff-Vision, or Endorings, which cannot be applied in clinical settings because of the restrictions of the National Health Insurance system in Korea, and determining whether there is any synergistic effect with the simultaneous use of several methods are of vital importance. The addition of prone positioning to the combination of cap-assisted and water-exchange colonoscopy may prevent loop formation by redistributing abdominal pressure. Therefore, we aimed to compare ADR between the conventional colonoscopy (CC) and combination colonoscopy using modified cap-assisted and water-exchange colonoscopy with prone position (CWP).Combining the aforementioned methods can assist endoscopists in each phase of the colonoscopy–insertion, inspection, and intervention.This single-center, retrospective, case-control study was conducted at Baekyang Jeil Internal Medicine Clinic, Busan, South Korea. All procedures performed in studies involving human participants were performed in accordance with the ethical standards of the institutional and/or national research committee and with the 1964 Helsinki Declaration and its later amendments or comparable ethical standards. This study was approved by the ethics committee of the Institutional Review Board of Pusan National University, Yangsan Hospital . Informed consent was obtained from all participants included in the study. we compared the number of patients with positive FOBT for each group.Between December 2019 and March 2020, a total of 901 patients underwent colonoscopies at our clinic. In total, 442 patients underwent CWP and 459 underwent CC. The procedures were performed by 2 board-certified gastroenterologists, J.K. and S.H.H. S.H.H. had 10 years of experience in CC, and J.K. had 3 years of experience in CC and 1 year in CWP. The exclusion criteria were age < 50 years, failed cecal intubation, poor or inadequate bowel preparation, previous colorectal resection, inflammatory bowel disease, colonic obstruction, and hereditary polyposis syndromes. Finally, among the 746 enrolled patients, 358 and 388 patients were included in the CWP and CC group, respectively  and EC38-i10F colonoscopes . A transparent cap was attached to the tip of the colonoscope . The modified cap-assisted colonoscopy, referred to as the “hooking and dragging method,” was performed by simultaneous hooking  and dragging (gentle retraction of the colonoscope dragging it down the multiple folds of the colon) the colonoscope down the colonic folds; for the procedure, a transparent hood was fitted onto the tip of the colonoscope.Colonoscopies were performed after preparing the bowel with 2 L of polyethylene glycol plus an ascorbic acid solution . Bowel preparation was evaluated and graded using the Aronchick scale.The colonoscopies were performed with the patients under midazolam-based conscious sedation. When polyps were detected, endoscopic observations and therapeutic interventions were carried out during the withdrawal phase. For both the procedures, the patients were initially made to lie in the left decubitus position. When the colonoscope reached the sigmoid colon, the patients in the CWP group repositioned themselves to a prone position and maintained the posture until the end of the procedure. During the colonoscopy, the patients used a hugging pillow to avoid chest compression; their oxygen saturation levels were monitored. The patients were sedated minimally because their cooperation was needed during the procedure for changing the position.In the CWP group, the colonoscope with the waterjet system was inserted into the rectum with the air pump turned off. Residual air and fluid were immediately suctioned out of the colon, and warm water (at 37°C) was infused. The scope was advanced, and in each colonic segment, this exchange  was performed. The appendiceal orifice was identified; water suction performed, and the air insufflated to facilitate the inspection and removal of the lesions. Upon the withdrawal of the scope, a transparent cap was used, and the haustral folds were flattened, to facilitate mucosal inspection. The air was insufflated to distend the lumen of the colon during scope insertion in the CC group. The water was used for irrigation only if bubbles or residual debris were encountered. The similarity and differences of the operations between 2 colonoscopies are summarized in Table Polyps with a diameter of ≥ 5 mm were removed by endoscopic mucosal resection or cold snare polypectomy. Polyps with a diameter of < 5 mm were removed with cold forceps polypectomy. All the removed polyps were examined pathologically, and the number of adenomas was determined. In this study, we defined the polyp detection rate (PDR) as the proportion of patients with at least 1 polyp, ADR as the proportion of patients with at least 1 adenoma, and MAP as the MAP .http://links.lww.com/MD/H688. The primary outcome was the comparison of ADR between the CWP and CC groups. The secondary outcome was the comparison of PDR and MAP between these 2 groups. In addition, MAP in the proximal colon  and the distal colon  were evaluated. The proximal colon was defined as the colon proximal to the splenic flexure, including the cecum, ascending colon, and transverse colon.The raw data used for statistical analysis are shown in Supplement, P value of < 0.05 indicated statistical significance. The statistical analyses were performed using SPSS 26 .Statistical comparisons between the 2 groups were performed using the Mann-Whitney U-test, and ADR and PDR were analyzed using Fisher’s exact test. A P < .01; 950.70 ± 438.45 vs 718.15 ± 325.96, P < .01; 599.4 ± 139.8 vs 501.54 ± 124.95, P < .01), respectively. However, there were no adverse events resulted from prolonged withdrawal time.The baseline characteristics between the CWP and CC groups are summarized in Table P < .001). A total of 442 patients (59.2%) had ≥ 1 adenoma, with 251 patients (ADR: 70.1%) in the CWP group and 191 patients (ADR: 49.2%) in the CC group. ADR was significantly higher among the patients in the CWP group (P < .001). MAP was also significantly higher in the CWP group than in the CC group . Proximal MAP was significantly higher in the CWP group than in the CC group ; however, distal MAP did not differ between the 2 groups . The comparison of MAP between the CWP and CC groups stratified by sex is summarized in Table The comparison of PDR, ADR and MAP between the CWP and CC groups is summarized in Table ,11 Although several methods, such as Endocuff, Endocuff-Vision, or Endorings, have been studied for these 2 quality indicators; in countries with a National Health Insurance System, such as in Korea, there are limitations in adopting these methods for private clinics. Therefore, it is important to determine whether ADR can be increased using conventional methods.Screening colonoscopy is used widely in the prevention of colorectal cancer. Among the quality indicators governing the efficacy of colonoscopy, ADR and MAP are important indicators that may lead to a decrease in the rate of interval cancer.The combination colonoscopies, including CWP, was effective in the detection of polyps and adenomas, especially those located in the proximal colon. These results may have been associated with the synergistic or complementary effects during the insertion and withdrawal phases. the water-exchange colonoscopy minimizes the colonic distension, facilitating the advancement of the endoscope without forming excessive loops, prone positioning, owing to the patient’s body weight, provides generalized abdominal pressure; it may allow the passage of the colonoscope in specific instances, such as when large loops, that are otherwise challenging to resolve, form in the transverse colon.,22 While these effects may not facilitate the effective inspection of the mucosa directly, they enable the movement of the colonoscopic tip and allows the endoscopist to concentrate, without exhaustion, particularly while inspecting the mucosa during the withdrawal phase.During the insertion (water exchange) phase, the transparent hood prevents the occlusion of the suction channel by creating a space between the mucosa and the suction port; besides, the continuous water exchange prevents the settlement of debris onto the cap attachment. This interaction enables uninterrupted water exchange and a clear visualization during the insertion phase. Whereas, combination colonoscopy induces a synergistic effect, resulting in the prevention of loop formation and facilitation of cecal intubation by the following mechanisms: the cap-assisted colonoscopy provides better visualization of the lumen in the colonic flexures and the sigmoid colon, facilitating the advancement of the endoscope without forming excessive loops and inadequate air insufflation, and better visualization of proximal side of mucosal folds on cap-assisted colonoscopy–25 may explain why proximal MAP, but not distal MAP, showed a significant increase in the CWP group. We also used a modified version of the cap-assisted colonoscopy, referred to as the “hooking and dragging maneuver”. The conventional cap-assisted colonoscopy flattened a single mucosal fold, while the modified cap-assisted colonoscopy hooked  and dragged  multiple mucosal folds simultaneously. This modified method simultaneously allowed the inspection of the proximal and distal parts of the mucosal folds, minimizing blind spots. Figures  an important thing has been overlooked. In cap-assisted colonoscopy, no attempt was made to standardize the usage of the cap, and it is likely that non-standardized usage influenced the results of the analysis. A study about artificial intelligence identifying blind spots showed that a single endoscopist with an ADR of 47% missed 1% to 50% of the total colon surface area (median 19%). Using the cap only for insertion as well as for “hooking and dragging maneuver” is likely to decrease the potential for a blind spot. Thus, it is necessary to reanalyze ADR and blind spots according to the cap usage maneuver and standardize it. In this study, ADR in the CWP group (70.1%) were higher than that of previous studies with 40.5% in cap-assisted colonoscopies , 41.7% in water exchange colonoscopies , and 44% in cap-assisted water immersions . High ADR in this study could be associated with the high quality and long withdrawal time of CWP. The significantly longer withdrawal time in the CWP group compared to the CC group was not only due to the additional time required for subsequent polypectomies that resulted from high detection rates but also because of the “hooking and dragging maneuver” in the modified cap-assisted colonoscopy. Compared to no polyp detected cases, withdrawal time is also significantly longer in the CWP group . In addition, comparing PDR, ADR and MAP between males and females, males were significantly higher than females in total patients, the CWP and the CC groups. These findings were consistent in that of previous studies.,32 Although exact pathophysiologic mechanisms are still unknown, the differences of levels of hormones, smoking rates, metabolic syndrome, and lifestyle may be the associated factors for sex differences.,34Improved quality of cleanliness on water-exchange colonoscopy investigating the combined method without the prone position, ADR for the combination of the water-exchange and cap-assisted colonoscopies was 75%  and was consistent with ADR of this study. However, MAP (1.69 ± 1.93) of this study was lower than MAP (2.70 ± 3.27) obtained in their study. Considering that most of the participants in the study by Yen et al were males , we evaluated PDR, ADR, MAP and proximal MAP according to sex. In this study, the PDR, ADR, and MAP in males were 92.1%, 82.8%, and 2.28 ± 2.24, respectively. High ADR in both the study by Yen et al and this study demonstrated that the combination of cap-assisted and water-exchange colonoscopies facilitated the detection of adenomas by the aforementioned synergistic or complementary effects. Yen et al used Olympus PCF-H180AL colonoscope , with variable stiffness capability, in patients without changing their posture to the prone position, however, the prone position can be helpful while using a colonoscope without variable stiffness capability.According to the study by Yen et al,,36 and body mass index, which could have led to an increase in loop formation. Third, the endoscopists were non-blinded to the methods used in this study, which may have been a potential source of investigator bias. Fourth, only 2 of the endoscopists participated in this study, and they performed only 1 method according to their skill proficiency. Fifth, the benefit of prone position in combined colonoscopy was unclear. Therefore, further evaluation such as a prospective, multicenter study using fluoroscopy needed to prove the role of prone position in colonoscopy.This study had some limitations. First, this was a retrospective study and was performed in a single center; hence, the potential selection or information bias may have existed. Second, we could not investigate the patients’ family history of colorectal cancer smoking history, stool frequency and stool property, which could have influenced ADR,In conclusion, ADR and MAP in the CWP group were significantly higher than that in the CC group, suggesting that CWP could be more useful than CC. Although this technique can improve adenoma detection, further evaluation to assess these synergistic effects is required.


This corresponds to an effective dose of 1.5 μSv for a lateral cephalogram, 7 μSv for an OPG, and 33.8 μSv for CBCT. Of the 9680 images, 78% were orthopantomograms, and only 0.4% were CBCT images. OPG has become more important over the years, as reflected in the indication. Approximately one-third of all extraoral exposures are orthodontic indications. Overall, the indications were similar for both genders. According to the dental indications, boys were X-rayed slightly more frequently than girls (54.5–45.5%). A future publication of dose guide values and corresponding guidelines is of high priority. Children are exposed to ionizing radiation through radiographs during their development for various reasons. At present, there are no officially valid reference values for dental X-rays in children and adolescents for dental X-ray diagnostics. This study retrospectively examined 9680 extraoral dental radiographs in pediatric patients between 2002 and 2020. The aim was to analyze the radiation doses in pediatric patients, which indications were used, and whether there were specific age and gender differences. The evaluation showed that radiation doses were considered low, with dose area products of 2.2 cGy × cm Children and adolescents are particularly sensitive to ionizing X-rays. The consequences of radiation can be far-reaching and can affect the rest of their lives. Therefore, a sensitive approach to radiation is necessary, especially for children and adolescents. The risk of radiation damage is conditioned by various factors. An important role is played by the division rate of the cells, which is higher the younger the patient. Furthermore, the water content of children’s tissue is significantly higher, meaning that proportionally more radiation is required for the same tissue layers. In addition, sensitive radiation regions are closer together the smaller and more compact the patient’s body is. Consequently, these areas are usually located within the radiation field. The distribution of red bone marrow is also different in children compared with the adult body. In infants, for example, it is present in all areas, including the skull, which is much more important in percentage terms than in adults. Therefore, the risk is correspondingly high. In general, the probability of late effects increases with the length of life still to be expected ,2. ThereIn dentistry, radiological imaging using X-rays is an important diagnostic procedure. The first image of teeth was made as early as 1896 by Friedrich Otto Walkhoff . Since tThe majority of dental X-rays in children and adolescents are taken in the field of pediatric dentistry and orthodontics. Dental X-ray procedures are divided into two categories: intraoral and extraoral imaging techniques and two- and three-dimensional procedures. The present study refers exclusively to extraoral overview radiographs taken in two dimensions, such as orthopantomography (OPG) and lateral cephalograms, or in three dimensions, such as digital cone beam computer tomography (CBCT). OPG is used as a dental overview image in pediatric dentistry for caries diagnostics and for assessing anatomical structures in the tooth, mouth, and jaw regions. OPG and lateral cephalograms together are used for orthodontic diagnostics to establish an appropriate treatment plan and to verify the success of treatment . HoweverThis study aimed to investigate the number and dose values of dental X-ray examinations in children and adolescents at the University Hospital in relation to the modalities of OPG, lateral cephalograms, and CBCT from January 2002 to July 2020. The aim is to determine both the dose area product of a single X-ray examination and the resulting effective dose for the patient and, simultaneously, to illustrate how this should be assessed compared to other radiation exposures. The number of X-ray examinations was analyzed both on an annual and modality basis. In addition, the indications were examined more closely to show whether they have changed over the years. Individual indications were analyzed for age peaks.The Radiology Information System (RIS) of i-SOLUTIONS Health GmbH  and the Picture Archiving and Communication System (PACS) of GE Healthcare were used to collect the data. The data were extracted from the above programs by the University Hospital Computer Center. The patient base included all children and adolescents aged 0–18 (up to age 18) who had a radiograph taken between 1 January 2002 and 31 July 2020.The following patient parameters were used as additional filters: identification number, hospital information system identification number (HIS ID), pseudonym with the date of birth, and gender. Examination date, doc type, room/device, dose area product, indication, and modality were also filtered out. The above information was compiled on the modalities of OPG, lateral cephalogram, and CBCT and formatted into an Excel spreadsheet. Extraoral images from OPG, lateral cephalogram, and CBCT were evaluated.Subsequently, the values for the dose area product of the individual modalities were determined uniformly and supplemented. Using the dose values, an effective dose for the patient could be determined using the following formula: .To determine suitable conversion factors (CFs), the work of Gosch et al. (2007)  from theIn the case of OPG and CBCT, radiation exposure occurs correspondingly from several viewing angles due to the rotation around the patient. This must be taken into account in the CF. For OPG, the tube voltage is 64–69 kV at the University Hospital . To establish a uniform CF for this modality, the value between 60 kV and 70 kV was averaged from the table. The projections resulting from the slightly more than half-ellipsoidal movement were also considered . Consequently, the following calculation was applied according to the recommendations of the medical physics expert: Due to the tube voltage of 85 kV in CBCT, an averaged factor was used, also considering the X-ray planes due to the  circular motion . The result is as follows: Statistical analysis was performed with IBM SPSS Statistics 27 using descriptive statistics as well as absolute and relative frequency distributions for categorical characteristics, such as age, gender, year, or indication. Mean models, with patient age as the dependent variable, were also used. Patient age was used as the outcome variable combined with HIS ID, which was individually assigned to each patient, as a random effect in linear mixed models (random effects model). Furthermore, cross-tabulations were conducted to better elicit associations. Multiple tests were revised using the Bonferroni correction.The determination of the documented dose area product for OPG, lateral cephalogram, and CBCT X-ray examinations in children and adolescents at the University Hospital and effective doses after conversion from mSv to μSv resulted in the following values :From 1 January 2002 to 31 July 2020, a total of 9.680 dental radiographs were taken in children and adolescents in the form of OPG, lateral cephalogram, or CBCT. The analysis showed that the number of yearly radiographs varied over time . In 2002As shown in the simplified modality representation, panoramic radiographs were performed most frequently among the three overview modalities in the abovementioned period. A total of 7546 (78%) orthopantomograms and 2097 (21.7%) lateral cephalograms were recorded, but CBCT was used only 37 times (0.4%). OPG was applied more frequently in percentage terms over the period. When the ratio of modality frequencies was compared within a year, a decrease in lateral cephalogram abundance and an increase in OPG abundance were evident. For example, at the beginning of the survey in 2002, 30.6% of the 834 images were lateral cephalograms, and 69.4% were OPGs. By contrast, in 2019, only 14.1% were lateral cephalogram images, and 84.8% were OPG images. CBCT was first used in children and adolescents at the University Hospital in 2010, when the fewest procedures were performed at two exposures (0.4%). Subsequently, the frequency varied and reached its maximum in 2019 at seven exposures (1.1%).On average, the children who underwent CBCT scans were the oldest . Lateral cephalogram images accounted for a lower average of 0.2 years (approximately 2.5 months). The average age for OPG was the lowest at 11.9 years. However, several different imaging options were offered. When all these findings were considered, a wide range of ages for orthopantomograms was obtained. On average, the patients were 12.7 years old for the standard OPG program but were almost three years older for the OPG temporomandibular joint (TMJ) program. Children were the youngest in the OPG-child admission type at 5.5 years and OPG-without TMJ right at 9.6 years. Regarding gender, boys were examined for the first time using CBCT at 5 years, approximately three years earlier than girls (8 years). Overall, girls, on average, were slightly older than boys for all imaging types . The folp = 0.008).The youngest patient age for dental X-ray diagnostics was found in the indication caries diagnostic. The average age of the children was 9.2 years. They were slightly older, on average, for orthodontic imaging (12.7 years), and the oldest for X-rays related to prosthetic dentures (15.7 years), which was the aplasia case by five patients. On average, the female patients were older, except for the indications of caries diagnosis, orthodontics, and trauma  or a prosthetic denture (five OPG images). p < 0.001). If the frequency of indications was compared across genders, it could be seen that all indications were descriptively more frequent in boys than in girls. There were also significant differences in frequency among male patients for the indications apical diagnostics (p = 0.047), caries diagnostics (p = 0.007), dental surgery (p < 0.001), trauma (p < 0.001) and prosthodontics (p = 0.004) (= 0.004) .In addition to the relative frequency of gender, the finding of increased trauma-related X-rays in boys was confirmed when the absolute number was considered in the cross-gender comparison. Boys were X-rayed 322 times, whereas girls were X-rayed only 148 times.The distribution of indication frequencies by gender was predominantly comparable for boys and girls. A conspicuous feature was the orthodontic indication in girls, which accounted for 36.4%, a higher percentage of all indications than in boys (31.7%) . In the gender comparison, boys were X-rayed more frequently than girls. Statistically, 5–10% more dental X-rays were taken in boys yearly. Only 2020 showed a deviation. However, this value had limited significance, as the dataset only extended to 31 July 2020, not to the end of the year. Overall, there were 874 more exposures for boys. 2); OPG = 0.008–0.132 mSv/(Gy × cm2); CBCT = 0.035–0.31 mSv/(Gy × cm2)). The OPG–KF from Looe et al. was the basis for the 2018 study of Schwabl from Graz. The investigations and calculations on OPG images contained therein showed an effective dose of 10–14 μSv for the Promax 3D Max X-ray unit in adolescents and 39–54 μSv for the Orthophos XG 3D [For the final comparison, the calculated CFs were compared with the values from the literature. Looe et al. examined the CF for lateral cephalogram images (taking into account the recommendation of the ICRP) in 2007 and the CF for OPG in 2008 ,10. The os XG 3D . FurtherThe determination of dose exposure values showed that they were very low in relation to other typical radiographic procedures . For exaThis study aimed to analyze the extraoral radiographic procedures of children and adolescents up to 18 years of age for various aspects in a university dental radiology department from January 2002 to July 2020. The radiation exposure, frequency distributions, and different indications were evaluated in more detail. To the best of our knowledge, there are only a few studies that examined the topic and number of dental extraoral X-ray procedures in children and adolescents. A Finnish study from 2016 showed that extraoral radiographs in 7–12-year-old children accounted for the predominant share of dental radiographic examinations, with indications of orthodontics taking up the largest share at 95% ,18. In oOther indications in the 2016 Finnish study by Pakbaznejad Esmaeili et al. were caries diagnosis, trauma, infections, postoperative evaluations, and TMJ pain ,18. ThisIn our study, extraoral images were performed less frequently in caries diagnostics at 10–15 years than at earlier ages. The reason for this could be that younger children usually tolerate a panoramic radiograph better than intraoral radiographs, although this is the actual standard procedure for caries diagnosis in primary and mixed dentition. A Dutch study reported that it was not possible to take a bitewing radiograph for caries diagnosis by 6-year-old children in 18% of patients . As a reAs is generally known, it is important to be aware that radiation can cause damage to health whenever X-rays are indicated. Until now, there have been no diagnostic reference values in Germany for dental overview images for children and adolescents in the form of OPG, lateral cephalogram, or DVT. Many studies have discussed the relationship between dental X-rays and cancer development in recent years. In particular, older studies have pointed out an increased risk of leukemia , thyroidIt should be noted that the radiation dose to which the patient is exposed is proportional to the level of cancer risk but has no influence on the severity of possible cancer ,35. HoweIn general, there is a twofold increased risk of suffering stochastic radiation damage below the age of 20 years and a threefold increased risk below the age of 10, regardless of gender. The risk decreases with increasing age and is negligible after the age of 80, as the latency period between radiation exposure from X-ray imaging and the probability of developing cancer, in all likelihood, exceeds the lifetime.It is only possible to find comparative dose values for dental X-rays in children and adolescents to a limited extent because many studies use different measurement methods and units. Moreover, in vivo dose measurement is currently not possible . The limFurther studies using the compiled dataset could be performed in the future. It would be interesting to analyze one child as an individual in the longitudinal course by determining how often the same patient was examined and with which dose. Thus, one could establish estimates for the cumulative dose in childhood and show how often and with which cumulative dose children are X-rayed on average in the first 18 years of life, depending on the question.The evaluation of this study showed that X-ray procedures have become almost indispensable for dentistry, for children and adolescents as well. So far, however, no dose limits or reference values in dental X-rays of children and adolescents exist. The radiation dose to which a patient is exposed during extraoral X-ray procedures can be considered low in comparison to other X-ray exposures in the field of human medicine, or even to natural radiation exposure  . HoweverOPG, as an extraoral radiographic procedure, was used more frequently during the period under study. In total, 78% of all overview images performed in the dental area were orthopantomograms. This was also reflected in the indications, with orthodontic issues accounting for the largest proportion (approximately one-third). In summary, the analysis showed that extraoral X-ray procedures are of great importance, especially for this specialty.Even if there is no risk of deterministic radiation damage, the probability of stochastic damage may increase due to the frequency of the examinations. Therefore, in principle, developing a tumor due to frequent dental radiographs is possible. As children and adolescents have more radiation-sensitive organ regions and the probability of late effects increases with the length of their expected lifespan, this risk is particularly high. Thus, these indications should be critically examined. In the future, uniform diagnostic reference values for all radiographs in the dental field should be defined as part of quality assurance. In addition to having quality criteria and comprehensive staff training, these can ensure the adequate handling of ionizing radiation.


The fermented tea beverage Kombucha is obtained through a series of biochemical and enzymatic reactions carried out by symbiotic cultures of bacteria and yeasts (SCOBY). It contains organic acids, vitamins, amino acids, and biologically active compounds, notably polyphenols, derived mainly from tea. Kombucha exhibits a range of health-promoting properties, including antioxidant or detoxifying effects. This fermented beverage is traditionally brewed with black tea, but other types of tea are used increasingly, which may have significant implications in terms of chemical composition and health-promoting effects. In this preliminary study, we investigated the content of micronutrients (manganese (Mn), copper (Cu), iron (Fe), chromium (Cr) and zinc (Zn)) by the ICP-OES method in Kombucha prepared with black, red, green and white tea at different time points of fermentation . It should be noted that the composition of separate ingredients such as tea, leaven or sugar has not been studied. Kombucha had the highest content of zinc—0.36 mg/L to 2.08 mg/L, which accounts for between 3% and 26% of the RDA (Recommended Dietary Allowance) for adults, and the smallest amounts of chromium (0.03 mg/L to 0.09 mg/L), which however represents as much as between 75% and 232% of the RDA. It has been demonstrated that the type of tea as well as the day of fermentation have a significant effect on the concentrations of selected minerals. Kombucha can therefore supplement micronutrients in the human diet. Gluconobacter: G. entanii, G. oxydans, Acetobacter: A. xylionoides, A. aceti, A. pasteurianus), Komagataeibacter , lactic acid bacteria (LAB) (Lactobacillus and Leuconostoc), and yeasts . Its dynamics are still not fully understood [Kombucha is a low-alcohol beverage made by fermenting a sugared tea infusion with symbiotic cultures of bacteria and yeasts (SCOBY), commonly called “tea fungus”. This complex community comprises acetic acid bacteria (AAB) , amino acids , polyphenolic compounds, i.e., catechins and flavonoids, and a variety of minerals ,15,16,17It is worth noting that Kombucha has been hailed as a functional fermented beverage with antioxidant, antimicrobial, antioxidant, anti-diabetic properties, reducing cholesterol levels, supporting immune and digestive function, and also stimulating liver detoxification ,17,18,19In addition, Kombucha is gaining popularity as one of the novelties offered by fermented food manufacturers. The valuable composition of such foods translates into manifold biological effects in consumers’ bodies . As a reEven though Kombucha is gaining increasing recognition and the range of flavors available on the food market continues to expand, the detailed composition and the effects of individual fermentation parameters or type of tea on the properties of this product are not fully understood . A few sCamellia sinensis): black, green, white and red (Pu-ERH) originating in China.The material consisted of four types of leaf tea , eight grams of tea  and 1 L of hot distilled water (90 °C) were added to the flask. The solution was infused for 10 min in a sterile conical flask. After cooling to 30 °C, the tea decoction was filtered into clean glass bottles and Kombucha pellicle  and one hundred milliliters of leaven from a previous culture  were added  was added to each vial and each sample was allowed 30 min pre reaction time in the clean hood. After completion of the pre-reaction time, 0.5 mL of non-stabilized 30% H2O2 solution  was added to each vial. Once the addition of all reagents was complete, the samples were placed in special Teflon vessels and heated in the microwave digestion system for 35 min at 180 °C (15 min ramp to 180 °C and maintained at 180 °C for 20 min). At the end of digestion all samples were removed from the microwave and allowed to cool to room temperature. In the clean hood, samples were transferred to acid-washed 15 mL polypropylene sample tubes. A further 5-fold dilution was performed prior to ICP-OES measurement. A volume of 2 mL was taken from each digest. The samples were spiked with an internal standard to provide a final concentration of 0.5 mg/L Ytrium, 1 mL of 1% Triton  and diluted to the final volume of 10 mL with 0.075% nitric acid . Blank samples were prepared by adding concentrated nitric acid (500 µL) to tubes without a sample and subsequently diluted in the same manner described above. Multielement calibration standards  were prepared with different concentrations of inorganic elements in the same manner as in blanks and samples. Deionized water  was used for preparation of all solutions.The samples were mineralized using the MARS 5 CEM microwave digestion system. The volume of the sample given to research was 0.8 mL. The samples were transferred to clean polypropylene tubes, 2 mL of 65% HNOSample determination:Samples were analyzed using inductively coupled plasma optical emission spectrometry , which is often utilized to measure the concentrations of mineral nutrients as well as heavy metals and allows simultaneous measurements of many different elements, also in plant samples ,29. ICP-Validation was performed by evaluating the following: NIST SRM 8414 reference material , limit of detection (LOD), and the recovery of internal standard (yttrium). To eliminate possible interference, the emission lines were selected empirically in pilot measurements. This model of validation is often used in ICP-OES studies, also those regarding plant samples . The recp ≤ 0.05.All determinations were carried out in at least three replicates. Statistical analysis was performed using Stat Soft Statistica 13.0 and Microsoft Excel 2017. Distributions of values for individual parameters were analyzed using the Shapiro-Wilk test. Since the distribution of continuous variables deviated from normal, the Kruskal-Wallis test was used to evaluate the differences between the studied parameters. Spearman’s correlation test was used to determine the correlations between the parameters studied. Results were expressed as mean values and standard deviation; however, median values and quartile ranges were used for statistical analyses. Differences were considered significant at Analysis of Kombucha beverages prepared with black, green, white and red tea at different time points of fermentation revealed the presence of five trace elements . The conThe content of manganese in Kombucha ranged from 0.43 mg/L to 1.40 mg/L and was dependent on both fermentation time and type of tea used . StatistThe content of copper in Kombucha depended on both fermentation time and the tea used  and rangThe content of iron in Kombucha ranged from 0.18 mg/L to 0.46 mg/L and was dependent on both fermentation time and type of tea used . The lowThe chromium content in Kombucha ranged from 0.03 mg/L to 0.09 mg/L and was dependent on both fermentation time and type of tea used . The lowThe content of zinc in Kombucha ranged from 0.36 mg/L to 2.08 mg/L and was likewise dependent on both fermentation time and type of tea used . The lowIn addition, the content of micronutrients was analyzed independently of the day of fermentation, taking into account the type of tea used to prepare Kombucha. The highest concentrations of Zn, Cu and Cr were found in the beverage made with black tea. In the case of manganese, the highest concentration of this element was observed in Kombucha brewed with green tea, while that of iron in the Kombucha prepared with red tea . The onlAdditionally, significant positive correlations were found between some micronutrients ; howeverRegardless of the type of Kombucha, a weak but statistically significant correlation was found between time and the content of Mn (0.279), Zn (0.348) and a moderate, significant relationship between time and the content of Fe (0.423) and Cr (0.447).Regardless of the day of fermentation, quite strong relationships between the time and concentration of selected mineral compounds were shown in Kombucha fermented tea is becoming increasingly popular, not only for its sensory properties, but also for its health-promoting benefits. In addition, the drink is classified as a functional food or nutraceutical ,30,31.Our study confirms that Kombucha can be a source of micronutrients: chromium (Cr), manganese (Mn), copper (Cu), zinc (Zn), and iron (Fe). The general pattern of mineral concentrations in the Kombucha samples was as follows: Zn > Mn > Fe > Cu > Cr. Our analysis was carried out at different time points of fermentation . In addition, for the first time, different types of leaf tea were used as the base of the beverage: black, green, red and white tea. We have shown that the content of selected micronutrients is dependent not only on the day of fermentation but also on the type of tea used.Micronutrients are minerals which, although present in trace amounts, are essential for the normal development and functioning of the human body. Given that cells do not have the ability to synthesize trace elements, they must be supplied with food. A properly balanced diet should contain essential minerals in such quantities that the total supply is adequate to meet demand, as both deficiency and excess can cause a range of dysfunctions and disorders ,33. The Manganese plays an important role in development, digestion, reproduction, antioxidant defense, energy production, immune response and regulation of neuronal activity . The aduCopper is a component of superoxide dismutase and thus influences free radical decomposition reactions. Moreover, it is responsible for enzymatic reactions and the synthesis of collagen and neurotransmitters . The RDAp < 0.05).Iron, an essential mineral for health and life, is responsible for the synthesis of hemoglobin—a protein found in erythrocytes, which carry oxygen molecules from the lungs to peripheral tissues and support immune and nerve functions . To prevChromium is an essential nutrient for normal metabolism of glucose, protein and fat. It enhances insulin sensitivity in tissues and also participates in intracellular redox reactions. The recommended daily intake of this mineral for men and women aged 19–50 years is 0.04 mg ,38. Our Acetobacter aceti bacteria biotransform chromium and zinc and increase their amounts. These properties are used in the treatment of diabetes due to their hypoglycemic effect [Zinc (Zn) is a key element in many processes, from cell growth and differentiation, to regulating immune system function and modulating mechanisms related to learning and memory . The recc effect .Minerals such as Mn, Zn and Cu can find be found in plant protection products, fertilizers, pesticides and fungicides. Their presence in the product may be related to agricultural practices in use and the content of these elements in phytosanitary products .Kombucha, despite its long tradition, is not adequately researched. There are few studies analyzing the mineral content of this beverage, particularly in terms of micronutrients. It should be emphasized, however, none of them take into account the different time points of fermentation and type of tea.Ivanišová et al. assessed the chemical composition and antioxidant, antimicrobial and sensory properties of Kombucha made with black tea on day 7 of fermentation, and their findings appear to be consistent with the present study. Their Kombucha, however, was prepared in a different way. The infusion was made by boiling 1 liter of water, 5 g of black tea leaves  and 30 g of white sugar, left to steep for 15 min and fermented at 22 degrees Celsius for 7 days [Jayabalan et al. analyzed the chemical composition of the tea fungus (SCOBY) used to brew black tea Kombucha. Their study also made reference to time points, with tests carried out on days 7, 14 and 21 of fermentation. Biochemical properties, including mineral content, increased throughout fermentation time, reaching maximum values on day 21 [It is worth noting that similar findings were obtained in our earlier study focusing on fluoride ions. In that case, too, longer fermentation resulted in a higher fluoride concentration in the beverage .Similarly, a comparative analysis of sweet black tea vs. Kombucha showed that fermentation significantly increases the content of selected minerals . ConcentTea as such is an important source of elements in the human diet . What isBrzezicha-Cirocka et al. analyzed 118 black teas, determining the concentrations of 14 elements. In terms of micronutrients, the highest concentration was found for Mn, along with the highest percentage of the RDA (15%) per daily intake of this beverage . SimilarCamellia sinensis, and come from a single producer in China, they differ considerably in their production processes, as also demonstrated in this paper. Depending on the process followed to obtain the final product, different types of tea can be distinguished. The main types are black tea, white tea, green tea and red tea. Processing treatments affect the color, aroma, taste, intensity, and also the chemical composition of the tea infusion [Even though all teas used in this study are derived from the same plant species, infusion . Black tinfusion . White tinfusion . The geninfusion .In our study, irrespective of the day of fermentation, the content of individual micronutrients in Kombucha varied, with the type of tea being the determining factor. The highest concentrations of Zn, Cu and Cr were observed in the beverage prepared according to the traditional recipe, i.e., using the fully oxidized black tea. In the case of manganese, the highest concentration of this element was observed in Kombucha brewed with green tea, while that of iron in the Kombucha prepared with red tea. White tea, which undergoes the least amount of processing, only drying, gentle rolling and light oxidation, has the lowest concentrations of micronutrients. Hence, one of the factors determining the final mineral composition is the processing of the leaves themselves. Tea oxidation appears to be particularly important, as Kombucha made with black tea contained the highest levels of minerals.It is also worth noting that the micronutrient content increased with the day of fermentation of the beverage, reaching the maximum level on day 14. Today, a significant number of manufacturers embrace the use of fermentation in food production, due to its positive effects on enhancing biosafety, extending shelf life and functional properties . It appeThe fermentation process increases the bioavailability of micronutrients and trace elements through the degradation of insoluble metal cation complexes and anti-nutritive substances such as oxalates, tannins and phytates . These cSometimes, microorganisms use individual elements for their own metabolism as a substrate to initiate the fermentation process or the synthesis of secondary metabolites, including vitamins and polyols . We alsoL. fermentum B4655, L. plantarum B4495, L. casei B1922, L. bulgaricus CFR2028 i L. acidophilus B4496 reduced the content of phytic acid when used to ferment soy milk at 37° C for 24 h. In addition, the results show an increase in Mg and Ca levels in fermented soy milk compared to control [with L. plantarum 299v significantly reduced the phytic acid content and improved the bioavailability of minerals such as Ca, Fe and Zn [Scientific studies have confirmed the potential of LAB strains to improve the bioavailability of minerals. The results confirm that the LAB strains LAB  control . Bahaciu control  showed te and Zn . This diThe limitations of this preliminary study include the lack of composition analysis of the discrete ingredients such as tea, leaven and sugar. These results will provide a complete understanding of the biochemical processes in Kombucha. Nevertheless, it should be noted that Kombucha, especially when subjected to a longer fermentation process, contains more organic acids, and thus its pH is strongly acidic. Moreover, the produced CO2 can start to accumulate between the drinks (Kombucha) and the biofilm (SCOBY). This can prevent the transfer of nutrients and thus block the continuity of chemical changes in the reaction environment. It should therefore be consumed in limited quantities, diluted with water or fermented for a shorter period of time .Our findings clearly show that the type of tea used to make Kombucha has a significant impact on the micronutrient content of the final product. In addition, fermentation time also determined the levels of selected minerals. Irrespective of the type of tea, the highest results were observed mainly on day 14 of fermentation. Kombucha had the highest content of zinc (0.36 mg/L to 2.08 mg/L), which accounts for between 3% and 26% of the RDA for adults, and the smallest content of chromium (0.03 mg/L to 0.09 mg/L), which, however, represents as much as between 75% and 232% of the RDA. Black tea proved to be the best source of Zn, Cu and Cr; green tea was rich in Mn; while red tea had the highest iron content. In conclusion, Kombucha, particularly based on black tea, can supplement micronutrients in the human diet.