Dental Radiologists Research Articles

Enhancement of early proximal caries annotations in radiographs: introducing the Diagnostic Insights for Radiographic Early-caries with micro-CT (ACTA-DIRECT) dataset

BackgroundProximal caries datasets for training artificial intelligence (AI) algorithms commonly include clinician-annotated radiographs. These conventional annotations are susceptible to observer variability, and early caries may be missed. Micro-computed tomography (CT), while not feasible in clinical applications, offers a more accurate imaging modality to support the creation of a reference-standard dataset for caries annotations. Herein, we present the Academic Center for Dentistry Amsterdam—Diagnostic Insights for Radiographic Early-caries with micro-CT (ACTA-DIRECT) dataset, which is the first dataset pairing dental radiographs and micro-CT scans to enable higher-quality annotations.MethodsThe ACTA-DIRECT dataset encompasses 179 paired micro-CT scans and radiographs of early proximal carious teeth, along with three types of annotations: conventional annotations on radiographs, micro-CT-assisted annotations on radiographs, and micro-CT annotations (reference standard). Three dentists independently annotated proximal caries on radiographs, both with and without micro-CT assistance, enabling determinations of interobserver agreement and diagnostic accuracy. To establish a reference standard, one dental radiologist annotated all caries on the related micro-CT scans.ResultsMicro-CT support improved interobserver agreement (Cohen’s Kappa), averaging 0.64 (95% confidence interval [CI]: 0.59–0.68) versus 0.46 (95% CI: 0.44–0.48) in its absence. Likewise, average sensitivity and specificity increased from 42% (95% CI: 34–51%) to 63% (95% CI: 54–71%) and from 92% (95% CI: 88–95%) to 95% (95% CI: 92–97%), respectively.ConclusionThe ACTA-DIRECT dataset offers high-quality images and annotations to support AI-based early caries diagnostics for training and validation. This study underscores the benefits of incorporating micro-CT scans in lesion assessments, providing enhanced precision and reliability.Graphical

Optimal Training Positive Sample Size Determination for Deep Learning with a Validation on CBCT Image Caries Recognition.

Objectives: During deep learning model training, it is essential to consider the balance among the effects of sample size, actual resources, and time constraints. Single-arm objective performance criteria (OPC) was proposed to determine the optimal positive sample size for training deep learning models in caries recognition. Methods: An expected sensitivity (PT) of 0.6 and a clinically acceptable sensitivity (P0) of 0.5 were applied to the single-arm OPC calculation formula, yielding an optimal training set comprising 263 carious teeth. U-Net, YOLOv5n, and CariesDetectNet were trained and validated using clinically self-collected cone-beam computed tomography (CBCT) images that included varying quantities of carious teeth. To assess performance, an additional dataset was utilized to evaluate the accuracy of caries detection by both the models and two dental radiologists. Results: When the number of carious teeth reached approximately 250, the models reached the optimal performance levels. U-Net demonstrated superior performance, achieving accuracy, sensitivity, specificity, F1-Score, and Dice similarity coefficients of 0.9929, 0.9307, 0.9989, 0.9590, and 0.9435, respectively. The three models exhibited greater accuracy in caries recognition compared to dental radiologists. Conclusions: This study demonstrated that the positive sample size of CBCT images containing caries was predictable and could be calculated using single-arm OPC.

Frequency of Middle Mesial Canal in Mandibular Molars

Being the most difficult to detect unusual canal in mandibular molars, creating greater anatomical complexity and thereby variability, it is important that careful investigation aids in successful endodontic treatments. Objective: To evaluate the incidence and features of MMC in mandibular molars; to study demographic parameters and dental factors that may have an effect on its detection. Methods: A cross-sectional study was performed at Shahida Islam Medical College (SIMC), Lodhran from September 2023 to March 2024, and contained a total of 148 patients. Data was assessed for the presence of MMC in first, second and third mandibular molars. Two expert dental radiologists evaluated the results of the X-ray films. Results: The prevalence of MMC was 18%, with complete and partial compartments seen in more than half the patients (77%). It was shown that MMCs were most commonly observed in 51-65 age group (21.28%); however, there were non-significant differences based on patient's age and gender or tooth type and position accompanying OAC site. Conclusions: In present study, MMC was noted in 18% patients. Statistically insignificant demographic or dental predictors for MMC were identified

The relation between persistent foramen tympanicum and degenerative bone alterations in temporomandibular joint region.

The aim of this study was to evaluate, using cone-beam computed tomography (CBCT), the relationship of persistent foramen tympanicum (PFT) with degenerative changes in the temporomandibular joint (TMJ) and the presence of pneumatized glenoid fossae and articular eminences. Two experienced oral and maxillofacial radiologists evaluated 510 CBCT scans, from which 94 patients were divided into two groups: G1-patients with PFT and G2-control group. The location of the PFT, presence, or absence of degenerative TMJ changes and morphology were evaluated. Similarly, all images were evaluated for the presence of pneumatized articular eminence and glenoid fossa. The Chi-square test and Fisher's Exact test were used for the categorical variables. A multinomial logistic regression model was performed for subgroup analysis. To assess the estimation-chance occurrence of TMJ alterations the Odds Ratio analysis was used. Statistically significant results were found for erosion, planning, and subchondral cyst. Regarding TMJ morphology, significant results were found for: round, flat, and others. Moreover, it was possible to observe that patients who had the PFT were approximately 48 times more likely to manifest TMJ alterations and approximately 3 times more likely to manifest articular eminence pneumatization. Since individuals who have FTP have a greater chance of having TMJ and PEA changes, it is important for the dental radiologist to be aware of these signs in CBCT scans for a correct diagnosis. CAAE: 34328214.3.0000.0104 (11/30/2014).

Assessment of awareness and attitude towards radiation hazards and safety in the general population

Background: Dental radiologists, technicians, and other personnel understand the significance of radiation risks and, consequently, patient safety. It is equally important to know the understanding of patients visiting the hospital,which will assist in identifying gaps in patient education. Methods: Patients (n=300) visiting the outpatient department were given a pre-validated questionnaire form, which consisted of 17 questions distributed separately in order to assess awareness and attitude. The responses collected were statistically analysed. Results: Patients who are literate and have fairly good socioeconomic status are expected to be more aware and concerned about their attitude towards radiation safety and hazards, although fewer illiterate people are also expected to be equally aware and concerned. Conclusions: Despite many efforts by authorities, there seems to be a need to spread more awareness about radiation safety and hazards among the general population, irrespective of their background characteristics and educational status, and thus improve their attitude towards the same.

Clinical Super-Resolution Computed Tomography of Bone Microstructure: Application in Musculoskeletal and Dental Imaging

PurposeClinical cone-beam computed tomography (CBCT) devices are limited to imaging features of half a millimeter in size and cannot quantify the tissue microstructure. We demonstrate a robust deep-learning method for enhancing clinical CT images, only requiring a limited set of easy-to-acquire training data.MethodsKnee tissue from five cadavers and six total knee replacement patients, and 14 teeth from eight patients were scanned using laboratory CT as training data for the developed super-resolution (SR) technique. The method was benchmarked against ex vivo test set, 52 osteochondral samples are imaged with clinical and laboratory CT. A quality assurance phantom was imaged with clinical CT to quantify the technical image quality. To visually assess the clinical image quality, musculoskeletal and maxillofacial CBCT studies were enhanced with SR and contrasted to interpolated images. A dental radiologist and surgeon reviewed the maxillofacial images.ResultsThe SR models predicted the bone morphological parameters on the ex vivo test set more accurately than conventional image processing. The phantom analysis confirmed higher spatial resolution on the SR images than interpolation, but image grayscales were modified. Musculoskeletal and maxillofacial CBCT images showed more details on SR than interpolation; however, artifacts were observed near the crown of the teeth. The readers assessed mediocre overall scores for both SR and interpolation. The source code and pretrained networks are publicly available.ConclusionModel training with laboratory modalities could push the resolution limit beyond state-of-the-art clinical musculoskeletal and dental CBCT. A larger maxillofacial training dataset is recommended for dental applications.

Numbering teeth in panoramic images: A novel method based on deep learning and heuristic algorithm

Dental problems are one of the most common health problems for people. To detect and analyze these problems, dentists often use panoramic radiographs that show the entire mouth and have low radiation exposure and exposure time. Analyzing these radiographs is a lengthy and tedious process. Recent studies have ensured dental radiologists can perform the analyses faster with various artificial intelligence supports. In this study, the numbering performance of Mask R-CNN and our heuristic algorithm-based method was verified on panoramic dental radiographs according to the Federation Dentaire Internationale (FDI) system. Ground-truth labelling of images required for training the deep learning algorithm was performed by two dental radiologists using the web-based labelling software DentiAssist created by the first author. The dataset was created from 2702 anonymized panoramic radiographs. The dataset is divided into 1747, 484, and 471 images, which serve as training, validation, and test sets. The dataset was validated using the k-fold cross-validation method (k = 5). A three-step heuristic algorithm was developed to improve the Mask R-CNN segmentation and numbering results. As far as we know, our study is the first in the literature to use a heuristic method in addition to traditional deep learning algorithms in detection, segmentation and numbering studies in panoramic radiography. The experimental results show that the mAp (@IOU = 0.5), precision, recall and f1 scores are 92.49%, 96.08%, 95.65% and 95.87%, respectively. The results of the learning-based algorithm were improved by more than 4%. In our research, we discovered that heuristic algorithms could improve the accuracy of deep learning-based algorithms. Our research will significantly reduce dental radiologists’ workload, speed up diagnostic processes, and improve the accuracy of deep learning systems.

Detecting calcified pulp stones in patients with periodontal diseases using digital panoramic and periapical radiographies

Background/purposePulp stones are discrete calcified masses appearing in the dental pulp of healthy, disease and unerupted teeth. They are presented freely within the pulp tissue or attached and embedded in any part of coronal and radicular dentin. Here, the purposes of this study were to identify the presence of pulp stones in periodontal patients using digital panoramic and periapical radiographies, and to determine the association with gender, age, tooth type and dental arch.Materials and methodsThis is a retrospective study on selected records of 465 dental samples obtained between January and December, 2020. Data were collected from patients diagnosed with generalized chronic periodontitis and accepted the full periodontal treatment covered by the Government's Periodontal Health Care Program. Their digital panoramic (DPR) examination and full mouth periapical radiographic (DPA) examination (including 12 periapical and 4 bitewing images) were performed at the Outpatient Clinics of the Department of Stomatology, Taichung Veterans General Hospital. Patients were segregated into various groups according to their age, gender and tooth locations. All radiographic images were examined by a dental radiologist and two dentists to identify the presence of pulp stone calcifications and their associated factors using the Sirona applications software. Records were analyzed using SPSS version 22.0 based on tests of Pearson Chi-square and McNemar correlation.ResultsFrom 271 males and 194 females, a total of 465 DPR and 7440 DPA radiographs were studied. Pulp stone calcifications were identified in 270 (58.0%) subjects in DPR images and 348 (74.8%) subjects in DPA images (for 1 or more teeth per subject). We detected calcified opacities in 1031 teeth with DPR images and in 1326 teeth with DPA images from a total of 12,407 teeth. The incidence of pulp stones was similar across genders, but different in tooth locations and dental arch sextant. Moreover, pulp stones were detected more often on maxillary molars and subjects of old ages (>40 years). Digital panoramic and periapical radiography showed significant differences in the detection of pulp stone calcifications (P < 0.05), and detected better with digital periapical radiography examination.ConclusionWe found 58.0% (n = 645) of our patients with pulp stones using digital panoramic radiography, and 74.8% using digital periapical radiography. Regarding individual teeth, only 8.5% of pulp stones were observed in digital panoramic radiography and 10.6% in digital periapical radiography. Pulp stones were more often seen in maxillary molar teeth and old patients of ages >40 years old using periapical radiography examination especially in those patients with periodontally condition. As a two-dimensional imaging system, digital periapical radiography is recommended for a definitive and routine assessment in patients suspected of hard tissue abnormality and pulp calcification formation.

Radıologıcal Evaluatıon of the Recesses on the Posterıor Wall of the Nasopharynx wıth Cone-beam Computed Tomography.

The posterior wall of the nasopharynx is composed of loose connective tissue that includes many important anatomical structures. Various structures, such as the opening of the Eustachian tube (ET), the Rosenmüller fossa (RF), and the pharyngeal bursa (PB) are found here. To evaluate the nasopharynx posterior wall anatomic structures, including the Eustachian tube, Rosenmüller fossa, and pharyngeal bursa with cone-beam computed tomography. The depth, width, and length of the Eustachian tube, Rosenmüller fossa, and pharyngeal bursa were measured in 150 patients using axial-sagittal cone-beam computed tomography. The Eustachian tube and Rosenmüller fossa distance to the midsagittal plane, the coronal region passing through the posterior end of the nasal septum, the superior-inferior extremity of the recesses, and the nasal floor plane distance were measured. The relationship between Rosenmüller fossa types and other parameters were evaluated. The incidence of right Rosenmüller fossa types 1, 2, and 3 were 16%, 18%, and 66%, respectively, and that of the left Rosenmüller fossa types 1, 2, and 3 were 16%, 19.3%, and 64.7%, respectively. The mean pharyngeal bursa width, length, and depth were 10.8, 5.7, and 4.0 mm, respectively; those of the Eustachian tube were 5.6, 7.1, and 7.3 m, respectively; those of the right Rosenmüller fossa were 4.0, 12.4, and 10.5 mm, respectively; and those of the left Rosenmüller fossa were 3.8, 12.5, and 10.9 mm, respectively. The posterior wall of the nasopharynx contains several important anatomical structures. Evaluation of these using cone-beam computed tomography has many clinical and radiological advantages. To understand and interpret the coincidental findings in CBCT, dental radiologists should have access to more detailed information concerning the anatomy of the nasopharynx.

Avaliação da prevalência e localização de canais mandibulares bífidos. Um estudo em TCFC.

Aim: To investigate the prevalence and location of bifid mandibular canals (CMB) using cone beam computed tomography (CBCT). Materials and methods: Three trained and calibrated dental radiologists individually evaluated 1254 CT scans using the I-Cat Vision software (Imaging Sciences International®) and classified them into four distinct types (Retromolar, Dental, Forward and Bucolingual). Frequency data, collected from an Access form (Microsoft® Office), were analyzed using the Fischer and Friedman test. The level of statistical significance was set at 5%. Results: CMBs were found in 276 cases (22%), with no gender predilection (P = 0.186). There was a statistically significant difference between the types (P = 0.001). Discussion: The recognition of a CMB is of great relevance when associated with anesthetic and surgical procedures in the posterior region of the mandible. Although many studies have shown that CMB is not commonly seen, a failure to identify it can result in damage to the lower alveolar nerve (NAI) or difficulty in obtaining anesthetic block. Conclusion: The most frequent type of CMB in both genders was retromolar (P = 0.001), representing 18.5%, and visualized with rates of 47.1% in women and 52.9% in men. The frequency of CMBs analyzed using the CBCT was significant in the population evaluated and presented in different configurations. Thus, its investigation should not be neglected in the face of surgical procedures that involve the posterior region of the mandible.

Determination of a cone-beam CT low-dose protocol for root fracture diagnosis in non-endodontically treated anterior maxillary teeth.

The aim of this study was to determine a "low-dose protocol" which provides acceptable diagnostic accuracy for detection of root fractures in unrestored anterior maxillary teeth, using an ex vivo model. 48 maxillary anterior teeth, half with horizontal or oblique root fractures, were imaged using CBCT in an anthropomorphic model. Nine X-ray exposure combinations were used, including the manufacturer's standard ("reference") exposure and high-resolution settings ("HiRes"), by varying kV, exposure time, and rotation angle. Measurements of Dose Area Product (DAP) were recorded. Five dental radiologists assessed the scans for root fractures and judged image quality. Parameters of diagnostic accuracy were calculated, including area under the Receiver Operating Characteristic curve (Az). Objective measures of image quality were made at the same exposure combinations using an image quality phantom. Although there was a significant linear relationship between DAP and mean Az, only the lowest DAP exposure combination had a mean Az significantly different to the reference exposure. There was no significant effect on other diagnostic accuracy parameters when using HiRes compared with the reference exposure. There was a significant positive relationship between DAP and contrast resolution. HiRes did not significantly improve contrast resolution and made a small improvement to spatial resolution. Scope existed for radiation dose reduction compared with the manufacturer's guidance. There was no improvement in diagnostic accuracy using HiRes settings. A cautious recommendation for this CBCT machine is that it is possible to achieve a dose reduction of about 20% compared with the reference exposure parameters.

Morphologic Evaluations of Hypoglossal Canal using Cone Beam Computed Tomography

Hypoglossal canal (HC) which begins from very slightly above the inner part of the anterolateral portion of the foramen magnum and is located above the occipital condyle of the occipital bone. The aim of this study is to examine HC morphology and variations using cone beam computed tomography (CBCT). The morphology and types of HC were investigated with 303 CBCT images (606 side). Type 1 variation in 606 HC examined becomes the most commonly observed type (57.3%) while type 5 variation was the least common type of variation (0.8%). Type 1 HC was statistically higher in males (p=0.004). Because of HC, which is an anthropologically important point and enters the field of images in CBCT scan, it is recommended that dental radiologists should be aware of their variations and be wary of the pathologies that may occur in this region.

Metal artefact reduction in the oral cavity using deep learning reconstruction algorithm in ultra-high-resolution computed tomography: a phantom study.

This study aimed to improve the impact of the metal artefact reduction (MAR) algorithm for the oral cavity by assessing the effect of acquisition and reconstruction parameters on an ultra-high-resolution CT (UHRCT) scanner. The mandible tooth phantom with and without the lesion was scanned using super-high-resolution, high-resolution (HR), and normal-resolution (NR) modes. Images were reconstructed with deep learning-based reconstruction (DLR) and hybrid iterative reconstruction (HIR) using the MAR algorithm. Two dental radiologists independently graded the degree of metal artefact (1, very severe; 5, minimum) and lesion shape reproducibility (1, slight; 5, almost perfect). The signal-to-artefact ratio (SAR), accuracy of the CT number of the lesion, and image noise were calculated quantitatively. The Tukey-Kramer method with a p-value of less than 0.05 was used to determine statistical significance. The HRDLR visual score was better than the NRHIR score in terms of degree of metal artefact (4.6 ± 0.5 and 2.6 ± 0.5, p < 0.0001) and lesion shape reproducibility (4.5 ± 0.5 and 2.9 ± 1.1, p = 0.0005). The SAR of HRDLR was significantly better than that of NRHIR (4.9 ± 0.4 and 2.1 ± 0.2, p < 0.0001), and the absolute percentage error of the CT number in HRDLR was lower than that in NRHIR (0.8% in HRDLR and 23.8% in NRIR). The image noise of HRDLR was lower than that of NRHIR (15.7 ± 1.4 and 51.6 ± 15.3, p < 0.0001). Our study demonstrated that the combination of HR mode and DLR in UHRCT scanner improved the impact of the MAR algorithm in the oral cavity.

Volumetric and linear evaluation of the sphenoidal sinus of a Brazilian population, in cone beam computed tomography

The determination of sex from skeletal remains has been widely used in biological profile reconstruction since these are some of the last structures to perish after death. The sphenoid sinus is located deeply in the skull and is enveloped by diverse structures within the sphenoid body. It is, therefore, less predisposed to injuries and/or pathological changes. The aim of this study is to evaluate the possibility of determining sex in a Brazilian population by means of linear and volumetric measurements of the sphenoid sinus, in addition to identifying and quantifying the presence of extensions of this sinus in cone beam computed tomography (CBCT) scans. In total 268 CBCT scans were analysed, from patients aged between 22 and 70 years old, of which 145 were female, and 123 were male. The images, representative of a Brazilian population, were selected by a dental radiologist from a CBCT image bank. The volumetric measurements were made by means of the segmentation software ITK-SNAP 3.0® and the linear inferio-superior, latero-lateral and anteroposterior measurements, as well as the presence of extensions of the sphenoidal sinus, were made using the CS Imaging Software®. The results of this study suggested that when comparing men and women, there were no statistical differences in the linear measurements and extensions of the sphenoidal sinus, although the values were considerable in the extensions for the pterygoid processes and greater wings of the sphenoid bone, particularly in women. However, there was a statistically significant difference when the sphenoidal sinus volume was compared, as it was larger for men (11.364 mm³ ± 4.229 mm³) than for women (10.000 mm³ ± 3.615 mm³). In summary, the sphenoidal sinus volumetric measurements in CBCT exams are useful for determining the sex of unknown individuals.

Role of alloplastic reconstruction of the temporomandibular joint in the juvenile idiopathic arthritis population

We present outcomes following total joint replacement of the temporomandibular joint (TMJ) in adolescent and young adult patients with juvenile idiopathic arthritis (JIA), and discuss a multidisciplinary treatment model. A retrospective review was performed of patients presenting to the University of North Carolina Oral and Maxillofacial Surgery Service (Chapel Hill, NC) from 2016- 2018 who underwent unilateral or bilateral total replacement of the TMJ for a diagnosis of end-stage joint disease secondary to JIA. Inclusion criteria included diagnosis by a rheumatologist, presentation to our department in adolescence (under 18 years of age), surgical intervention in adolescence or young adulthood (under 25 years of age), and documentation of preoperative and postoperative pain, maximum incisal opening (MIO), and quality of life measures. A database was created and data were then analysed both qualitatively and quantitatively. Five patients met the inclusion criteria. All achieved MIO of more than 35mm with a mean improvement of 24mm, and were able to tolerate a regular diet. All preoperative pain had essentially been eliminated. All patients reported a considerable improvement in quality of life. To our knowledge, this is the first report to document a series of paediatric and young adult patients with JIA who required total replacement of the joint for end-stage joint disease. To our knowledge, it is also the first to describe the use of a collaborative clinic of oral and maxillofacial surgeons, neuroradiologists, dental radiologists, orofacial pain specialists, paediatric rheumatologists, and paediatric nurse practitioners, to care for these patients.

An investigation into dose optimisation for imaging root canal anatomy using cone beam CT.

To identify a dose as low as diagnostically acceptable and a threshold level of image quality for cone beam CT (CBCT) imaging root canals, using maxillary first molar (M1M) second mesiobuccal (MB2) canals of varying complexity for two CBCT scanners. Dose-area product (DAP) and contrast-to-noise ratio (CNR) were measured for two scanners at a range of exposure parameters. Subjective-image-quality assessment at the same exposures was performed for three M1Ms of varying MB2 complexity, positioned in an anthropomorphic phantom. Nine raters (three endodontists, three dental radiologists and three junior staff) assessed canal visibility, using a 5-point confidence scale rating. Identification of simple-moderate MB2 canal complexity was achieved at a range of protocols, with DAP values of ≥209.3 and ≥203.2 mGy cm² and CNRs of 3 and 7.6 for Promax®3D and Accuitomo-F170® respectively. For complex canal anatomy, target subjective image quality was not achieved, even at the highest DAP values for both scanners. Junior staff classified significantly more images as undiagnostic compared with senior staff (p = 0.043). In this first study to address optimisation of CBCT imaging of root canal anatomy, a similar threshold dose for both scanners was identified for M1Ms with simple-moderate MB2 canal complexity. Increasing dose to enhance visualisation of more complex canal anatomy was ineffective. Selection of standard protocols (while avoiding lower kV/mA protocols) instead of high-resolution scans was a practical means of reducing patient dose. CNR is not a transferable measure of image quality.

Diagnostic accuracy of panoramic radiography and ultrasonography in detecting periapical lesions using periapical radiography as a gold standard.

The purpose of this study was to compare the accuracy of imaging techniques in diagnosing periapical lesions. Imaging records of 80 patients (51 females, 29 males, aged between 14 and 75 years) including periapical and panoramic radiographs and ultrasonographic images were selected from databases of Selcuk University Dentistry Faculty. Periapical radiographs were accepted as gold-standard and 160 anterior maxillary and mandibular teeth with or without periapical lesion were included to the study. Three specialist observers (dental radiologists) evaluated the presence and appearance of periapical lesions on panoramic radiograph and ultrasonographic images.Sensitivity, specificity, positive predictive value, negative predictive value and diagnostic value of panoramic radiographs and ultrasonography were determined. Sensitivity was 0.80 and 0.77 for ultrasonographic images and panoramic radiographs, respectively which shows that periapical lesion was correctly detected in 80% of the cases with ultrasound and in 77% of the cases with panoramic radiography. Specificity values were determined as 0.97 for ultrasound and 0.95 for panoramic radiography. Overall diagnostic accuracy was 0.86 and 0.84 for ultrasound and panoramic radiography, respectively. Periapical and panoramic radiographs are commonly used to visualize periapical lesions. Besides, ultrasonography is an alternative method to digital radiographic techniques in the diagnosis of anterior teeth with periapical lesions.

Improved scan method for dental imaging using multidetector computed tomography: a phantom study.

This study aimed to propose an improved scan method to shorten irradiation time and reduce radiation exposure. The maxilla of a human head CT phantom and a Catphan phantom were used for qualitative and quantitative assessment, respectively. The phantoms were scanned by a 160-row multidetector CT scanner using volumetric and helical scanning. In volumetric scanning, the tube current varied from 120 to 60 to 30 to 20 mA with a tube voltage of 120 kV. Images were reconstructed with a bone kernel using iterative reconstruction (IR) and filtered back projection. As a reference protocol, helical scanning was performed using our clinical setting with 120 kV. Two dental radiologists independently graded the quality of dental images using a 4-point scale (4, superior to reference; 1, unacceptable). For the quantitative assessment, we assessed the system performance from each scan. There was no significant difference between the image quality of volumetric scanning using the 60 mA protocol reconstructed with IR and that of the reference (3.08 and 3.00, p = 0.3388). The system performance values at 1.0 cycles/mm of volumetric scanning and 60 mA protocol reconstructed with IR and reference were 0.0038 and 0.0041, respectively. The effective dose of volumetric scanning using the 60 mA protocol was 51.8 µSv, which is a 64.2% reduction to that of the reference. We proposed an improved scan method resulting in a 64.2% reduction of radiation dose with one-fourth of irradiation time by combining volumetric scanning and IR technique in multidetector CT.

Geographic distribution of dental specialists permitted to advertise dental practices in Japan.

The purpose of this study was to determine the geographic distribution of dental specialists permitted to advertise dental practices in Japan. We identified the populations of 349 secondary medical zones nationwide from the 2015 population census, as well as the number of dentists in five specialties, namely oral surgeons, pedodontists, periodontists, dental anesthesiologists, and dental radiologists, who had been permitted to advertise dental practices, from a 2016 survey of physicians, dentists, and pharmacists. We determined the placement rate, Lorenz curve, and Gini coefficient for dentists in each specialty in order to describe their geographic distributions. The placement rates of at least one of these types of dentist in each secondary medical zone were 73.9% for oral surgeons, 66.2% for pedodontists, 60.5% for periodontists, 31.8% for dental anesthesiologists, and 18.3% for dental radiologists. The Gini coefficients were 0.397, 0.400, 0.491, 0.650, and 0.761, respectively. The dentists in each specialty were few in number and were unequally distributed among the zones, but less so for oral surgeons and pedodontists. Dental anesthesiologists and radiologists were located primarily at university hospitals in urban areas and, therefore, were more unequally distributed.

Design the Conceptual Model of Teleconsultation System for Dental Diseases

Introduction: Worldwide, people living in rural and remote area with the lack of access to medical care are vulnerable. Despite of improvement in dentistry, dental caries is still one of the prevalent problems among people. By using tele-dentistry and transforming electronic patient information, dental services can be delivered specially in remote area so leads to improve public dental health.Methods: This is an applied development study and 24 dentists and dental radiologists were participated in this survey. The questionnaire was filled out by participant to obtain information about requirement for designing the conceptual model for teleconsultation system for dental problems. Collected data was analyzed by descriptive statics with SPSS version 22 software.Results: According to results patient name and last name, gender, emergency level, sign of the problem, patient history in patient demographic and clinical information section and in system capabilities section, dedicate the space for dentist to diagnosis and the space for seeing diagnosis report by patient was the 100 percent requirement considered. After requirement analysis conceptual model as use case diagram was designed.Conclusion: According to results, using tele-dentistry can improve relationship between specialists and patients without considering the distance and eventually improve public oral health in society.