For patients with partial jaw defects, cysts and dental implants, doctors need to take panoramic X-ray films or manually draw dental arch lines to generate Panorama images in order to observe their complete dentition information during oral diagnosis. In order to solve the problems of additional burden for patients to take panoramic X-ray films and time-consuming issue for doctors to manually segment dental arch lines, this paper proposes an automatic panorama reconstruction method based on cone beam computerized tomography (CBCT). The V-network (VNet) is used to pre-segment the teeth and the background to generate the corresponding binary image, and then the Bezier curve is used to define the best dental arch curve to generate the oral panorama. In addition, this research also addressed the issues of mistakenly recognizing the teeth and jaws as dental arches, incomplete coverage of the dental arch area by the generated dental arch lines, and low robustness, providing intelligent methods for dental diagnosis and improve the work efficiency of doctors.
Humans ; Radiography, Panoramic/methods* ; Cone-Beam Computed Tomography/methods* ; Head ; Image Processing, Computer-Assisted/methods*

Objective To evaluate the accuracy of different convolutional neural networks (CNN),representative deep learning models,in the differential diagnosis of ameloblastoma and odontogenic keratocyst,and subsequently compare the diagnosis results between models and oral radiologists. Methods A total of 1000 digital panoramic radiographs were retrospectively collected from the patients with ameloblastoma (500 radiographs) or odontogenic keratocyst (500 radiographs) in the Department of Oral and Maxillofacial Radiology,Peking University School of Stomatology.Eight CNN including ResNet (18,50,101),VGG (16,19),and EfficientNet (b1,b3,b5) were selected to distinguish ameloblastoma from odontogenic keratocyst.Transfer learning was employed to train 800 panoramic radiographs in the training set through 5-fold cross validation,and 200 panoramic radiographs in the test set were used for differential diagnosis.Chi square test was performed for comparing the performance among different CNN.Furthermore,7 oral radiologists (including 2 seniors and 5 juniors) made a diagnosis on the 200 panoramic radiographs in the test set,and the diagnosis results were compared between CNN and oral radiologists. Results The eight neural network models showed the diagnostic accuracy ranging from 82.50% to 87.50%,of which EfficientNet b1 had the highest accuracy of 87.50%.There was no significant difference in the diagnostic accuracy among the CNN models (P=0.998,P=0.905).The average diagnostic accuracy of oral radiologists was (70.30±5.48)%,and there was no statistical difference in the accuracy between senior and junior oral radiologists (P=0.883).The diagnostic accuracy of CNN models was higher than that of oral radiologists (P<0.001). Conclusion Deep learning CNN can realize accurate differential diagnosis between ameloblastoma and odontogenic keratocyst with panoramic radiographs,with higher diagnostic accuracy than oral radiologists.
Humans ; Ameloblastoma/diagnostic imaging* ; Deep Learning ; Diagnosis, Differential ; Radiography, Panoramic ; Retrospective Studies ; Odontogenic Cysts/diagnostic imaging* ; Odontogenic Tumors

ABSTRACT Dental anomalies may occur due to the complex interactions among genetic, epigenetic, and environmental factors during dental development. The current study aimed to determine the prevalence and gender significance of developmental dental anomalies (DDA) in dental patients. This was a cross-sectional study of 260 subjects (123 males and 137 females) with an age range of 6–35 years old. Clinical and radiographic examinations were performed to determine the prevalence of anomalies in tooth number, shape, size, position, and structure. Descriptive statistics was performed, the chi-square test was used for analysis and p-value was set at 0.05. The findings showed that 203 subjects (78.1%) had DDA, which included 86 males (33.1%) and 117 females (45%). A significant gender difference was found regarding the prevalence of two anomalies (p < 0.05). The most prevalent anomaly was displacement 51.2%, followed by dilaceration 24.2%. A significant gender difference (p < 0.05) was found regarding hypodontia 16.5% and impaction 14.6%, with more predominant in females. Some anomalies were not observed such as microdontia, dentin dysplasia, ectopic eruption, gemination, and taurodontism. The study concluded that displacement and dilacerations were the common abnormalities. These findings may lead to various dental complications. Therefore, early diagnosis and follow-up observation are required to reduce the potential dental problems. In addition, it is helpful to increase the knowledge of practitioners with regards to DDA and its occurrence. Furthermore, it is good to highlight the importance of early diagnosis of DDA, especially in the mixed dentition, which can lead to reducing the complication of an orthodontic treatment plan.
Tooth Abnormalities ; Radiography, Dental, Digital ; Libya

During the automatic reconstruction of panoramic images, the effect of dental arch curve fitting will affect the integrity of the content of the panoramic image. Metal implants in the patient's mouth usually lead to a decrease in the contrast of the panoramic image, which affects the doctor's diagnosis. In this paper, an automatic oral panoramic image reconstruction method was proposed. By calculating key image areas and image extraction fusion algorithms, the dental arch curve could be automatically detected and adjusted on a small number of images, and the intensity distribution of teeth, bone tissue and metal implants on the image could be adjusted to reduce the impact of metal on other tissues, to generate high-quality panoramic images. The method was tested on 50 cases of cone beam computed tomography (CBCT) data with good results, which can effectively improve the quality of panoramic images.
Humans ; Radiography, Panoramic/methods* ; Cone-Beam Computed Tomography/methods* ; Tooth ; Algorithms ; Image Processing, Computer-Assisted/methods*

OBJECTIVE: To evaluate the clinical effect of root canal obturation therapy using cold flowable gutta-percha on young permanent teeth after apexification. METHODS: Ninety cases of young permanent teeth with pulp necrosis or periapical periodontitis treated by apexification were randomly divided into two groups. The cases in each group were divided into single root canal and multiple root canal according to the number of the root canal, and divided into classifications Ⅰ, and Ⅱ/Ⅲ/Ⅳ according to Frank's classification of root development after apexification. Cold flowable gutta-percha and warm gutta-percha obturation techniques were used for root canal obturation of the two groups. The operation time was recorded, and the patients' therapy pain degree was evaluated by visual analog scale (VAS) immediately after operation. Periapical X-ray was performed after operation to evaluate the effect of the root canal filling. The total length of the root was divided into equal three parts on the X-ray film, and three-dimensional tightness of the apical, middle, and coronal region of the root canals were statistically analyzed respectively. Clinical examinations and X-ray examination were performed 6 and 12 months after the operation to evaluate the treatment success rate. RESULTS: The operation time of cold flowable gutta-percha group was significantly lower than that of the control group, which were 51 s and 74 s (P < 0.05); The percentages of pain and discomfort in the two groups were 26.67% and 40.00%, respectively. There were two cases of underfilling and no overfilling in both groups. The percentages of proper filling and tight three-dimensional obturation in the experimental and control groups were 71.11% and 60.00% respectively; and the percentages of tight three-dimensional obturation in the apical third areas were 86.67% and 66.67%, the difference was significant (P < 0.05). There was no significant difference in the three-dimensional tightness between the two groups in the middle and coronal third areas. The percentages of tight three-dimensional obturation in classification Ⅰ groups were 86.67%, 83.33%, 93.33% and 76.67%, 90.00%, 96.67% in experimental and control group, respectively; The percentages of classification Ⅱ/Ⅲ/Ⅳ groups were 86.67%, 86.67%, 100.00% and 46.67%, 86.67%, 100.00%, respectively, and the difference was significant (P < 0.05). There were no apical lesions that occurred in either group during the one-year review period. CONCLUSION The application of cold flowable gutta-percha on young permanent teeth root canal obturation after apexification can achieve good obturation effect. The root obturation effect in the apical third area is significantly better than that of warm gutta-percha obturation techniques. Cold flowable gutta-percha can shorten the clinical treatment time and ameliorate the patients' therapy comfort.
Apexification ; Dental Pulp Cavity ; Gutta-Percha ; Humans ; Radiography ; Root Canal Filling Materials ; Root Canal Obturation ; Root Canal Preparation

Objective To study the accuracy of Nolla method for age estimation of Northern Chinese Han children aged between 5.00 and 14.99 years based on original transformation tables and multiple regression model. Methods A total of 2 000 orthopantomographs （OPGs） were collected from the Hospital of Stomatology, Xi'an Jiaotong University, including 1 000 males and 1 000 females. Development stage of 7 left mandibular permanent teeth （except third molars） was assessed based on Nolla method, then age estimation was conducted through transformation tables and multiple regression model, respectively. Firstly, the development stage results of 7 permanent teeth were added up and the estimated age was obtained through the original transformation tables. Secondly, 80% of the samples （80 males and 80 females in each age group） were randomly selected from 2 000 OPGs as the train set. The chronological age of the selected patients was taken as the dependent variable, while gender and the development stage results of 7 permanent teeth were taken as the independent variable to establish multiple regression model. The remaining 20% of the samples were substituted into the model as the test set, to verify the accuracy of age estimation by multiple regression model. Results Mean chronological ages of males and females were 10.03±0.09 years and 10.01±0.09 years, respectively. The age estimated by original transformation tables showed an overestimation for males （0.18 years on average） and an underestimation for females （0.02 years on average）, with mean absolute error （MAE） of 0.94 years and 0.97 years, respectively. While the results by multiple regression model showed that males were overestimated by 0.06 years on average and females were underestimated by 0.02 years on average. The MAE was 0.66 years and 0.77 years, respectively. Conclusion The Nolla method is suitable for age estimation of Northern Chinese Han children. Compared with the original transformation tables method, the multiple regression model is more accurate for age estimation.
Adolescent ; Age Determination by Teeth ; Asian People ; Child ; Child, Preschool ; China ; Female ; Humans ; Male ; Molar, Third ; Radiography, Panoramic

ABSTRACT Panoramic X-ray is well known to cause DNA damage and induces cellular death. The aim of the present study was to evaluate the cytotoxicity of radiation exposure from panoramic radiography on human buccal mucosa cells by assessing the cell viability using the simple-trypan blue exclusion test. The genotoxicity effect was evaluated by assessing comet assay score. This research included a total of 20 healthy patients who had panoramic radiography for a routine dental examination. Buccal mucosa cells were collected from all participants before X-ray exposure and at 30 min or 24 h after exposure in Groups 1 and 2, respectively, and subjected to a comet assay and trypan blue exclusion test to assess cell viability and DNA damage. Cell viability was calculated as the ratio of live (translucent) to total counted cells. Comet assay output images were analysed using OpenComet software and a visual score by measuring the percentages of tail DNA and summing the visual score, respectively. A statistically significant (p < 0.05) reduce in cell viability was observed at 30 min after exposure, furthermore there is no more reduction after 24 h. Both comet assay measurements showed a significant (p < 0.05) increase in the percentage of tail DNA and visual score at 30 min after exposure, then tend to decrease after 24 h of exposure, although it was not significant (p > 0.05). The results showed that panoramic radiography interfered cell viability and induced DNA damage in buccal mucosa cells within 30 min after exposure, but these effects were ceased after 24 h.
Mouth Mucosa--cytology ; Radiography, Panoramic

OBJECTIVE: To compare the effects of different imaging methods on radio-opacity. Digital imaging and traditional film imaging were used to determine the radio-opacity of dental composite resin materials. METHODS: Fourteen dental composite resins commonly used in clinic were prepared for disc samples with thickness of 1 mm and diameter of 15 mm respectively. The aluminum step wedge was used as the reference and the disc samples were irradiated with X-rays by the traditional film imaging, phosphor imaging plate and charge-coupled device(CCD) intra-oral X-ray sensor respectively. Exposure was set at 65 kV and 7 mA, with 300 mm focus to film distance and the exposure time was 0.25 s. After developing and fixing the film, the optical density of the image of the sample and that of each step of the aluminum step wedge were measured using the densitometer. The digital image file was exported to grey scale analysis software of Adobe Photoshop^® to measure the average grey value in the sample image and aluminum step wedge image. The curves were drawn corresponding to the optical density/gray value of each step of the aluminum step wedge and its thickness, and the equivalent thickness of the aluminum plate was calculated according to the optical density/gray value of the actual measured thickness of the sample, so as to evaluate the radio-opacity of dental composite resin material. RESULTS: For the same sample, the aluminum equivalent measured by traditional film imaging and two other digital imagings had significant differences among the 14 composite resins (P < 0.05), and the aluminum equivalent measured by the two digital imagings were greater than that of the traditional film. Moreover the aluminum equivalent measured by the two digital imagings was also different, and the aluminum equivalent measured by the CCD intra-oral X-ray sensor in most composite resins was larger than that measured by phosphor imaging plate. The same sample was photographed with the same imaging method, and the aluminum equivalent was different after three exposures. The standard deviation of aluminum equivalent measured by phosphor imaging plate was the largest, while that measured by CCD intra-oral X-ray sensor was the smallest. Among the 14 dental composite resin materials, the aluminum equivalent of Tetric N-Ceram and Te-Econom Plus measured by traditional film imaging and phosphor imaging plate was significantly higher than other composite resins. CONCLUSION Based on clinical significance, three kinds of sensors designed to measure the radio-opacity of dental composite resin, the value of aluminum equivalent will change according to different types of sensors. The aluminum equivalent measured by CCD intra-oral X-ray sensor was higher than that measured by phosphor imaging plate, and the aluminum equivalent measured by phosphor imaging plate was higher than that measured by traditional film imaging. Moreover, even though the same sensor was used, the aluminum equivalent measured by multiple exposures was different. The standard deviation of the aluminum equivalent measured by phosphor imaging plate was greater than that measured by traditional film imaging and CCD intra-oral X-ray sensor. The three sensors in this study could be used for evaluating the radio-opacity of dental composite resin materials. But no matter what kind of sensor was used to measure the radio-opacity of dental composite resin, it complied to ISO 4049: 2019 standard, the materials were suitable for clinical use.
Aluminum ; Composite Resins ; Radiography, Dental, Digital

OBJECTIVES: Pentoxifylline (PTX) is a methylxanthine derivative that has been implicated in the pathogenesis of peripheral vessel disease and intermittent lameness. The purpose of this study was to investigate the effect of PTX and tocopherol in patients diagnosed with osteoradionecrosis (ORN), bisphosphonate-related osteonecrosis of the jaw (BRONJ), and chronic osteomyelitis using digital panoramic radiographs.MATERIALS AND METHODS: This study was performed in 25 patients who were prescribed PTX and tocopherol for treatment of ORN, BRONJ, and chronic osteomyelitis between January 2014 and May 2018 in Seoul National University Dental Hospital. Radiographic densities of the dental panorama were compared prior to starting PTX and tocopherol, at 3 months, and at 6 months after prescription. Radiographic densities were measured using Adobe Photoshop CS6 (Adobe System Inc., USA). Blood sample tests showing the degree of inflammation at the initial visit were considered the baseline and compared with results after 3 to 6 months. Statistical analysis was performed using the Mann–Whitney test and repeated measurement ANOVA using IBM SPSS 23.0 (IBM Corp., USA).RESULTS: Eight patients were diagnosed with ORN, nine patients with BRONJ, and the other 8 patients with chronic osteomyelitis. Ten of the 25 patients were men, average age was 66.32±14.39 years, and average duration of medication was 151.8±80.65 days (range, 56–315 days). Statistically significant increases were observed in the changes between 3 and 6 months after prescription (P<0.05). There was no significant difference between ORN, BRONJ, and chronic osteomyelitis. Only erythrocyte sedimentation rate (ESR) was statistically significantly lower than before treatment (P<0.05) among the white blood cell (WBC), ESR, and absolute neutrophil count (ANC).CONCLUSION: Long-term use of PTX and tocopherol can be an auxiliary method in the treatment of ORN, BRONJ, or chronic osteomyelitis in jaw.
Bisphosphonate-Associated Osteonecrosis of the Jaw ; Blood Sedimentation ; Humans ; Inflammation ; Jaw ; Leukocytes ; Male ; Methods ; Neutrophils ; Osteomyelitis ; Osteoradionecrosis ; Pentoxifylline ; Prescriptions ; Radiography, Panoramic ; Seoul ; Tocopherols

Objective To discuss a new coding method for individual identification based on oral panoramic tomography, analyze the diversity of different coding modules in nonhomologous images and the consistency and the matching rate of the coding indexes of different coding modules in homologous images, and evaluate the application value of the different modules and the new coding method in individual identification. Methods The oral panoramic tomography images of 1 000 patients with permanent teeth were collected retrospectively. Each patient had two images taken at different times （called the Early database and the Late database according to the chronological order）. Each image was coded according to the designed coding method. A computer program was designed to compare the diversity of different modules, and calculate the diversity and consistency of different coding modules as well as the matching rate of the coding indexes. Results The diversity of the 4 modules that reflected teeth characteristics was much higher than that of other modules in the same database. The highest diversity was noticed in the module of right mandibular teeth in samples of both databases. The coding consistencies of the 4 modules were all above 50%. Besides, 90.2% of the matching rates of indexes of homologous images were over 80%. Conclusion The 4 modules have higher application value in individual identification, especially the right mandibular teeth. The coding method has a certain value in forensic individual identification.
Forensic Dentistry ; Forensic Medicine ; Humans ; Radiography, Panoramic ; Retrospective Studies ; Tooth/diagnostic imaging*