우리나라의 구내 치근단 및 파노라마방사선촬영의 진단참고수준

Objective : The objective of this study was to suggest the diagnostic reference levels for intraoral and panoramic radiography through the nationwide survey at regular intervals in South Korea. Study Design : One hundred twenty-six dental institutions from all regions of South Korea were visited. Information on radiographic equipment and clinical exposure parameter was recorded at 118 intraoral and 125 panoramic equipment. Patient entrance dose (PED) and dose-area product (DAP) in intraoral radiography and DAP in panoramic radiography were measured using a DAP meter. Results : Third quartile PED and DAP of intraoral radiography in adults were 1.5 mGy and 46.0 mGy cm2 , those in 12-year-old children 1.2 mGy and 37.1 mGy cm2 and those in 6-year-old children 1.0 mGy and 29.9 mGy cm2 . Third quartile DAP of panoramic radiography in adults, 12, and 6-year-old children were 227 mGy cm2 , 175 mGy cm2 , 163 mGy cm2 , respectively. The median exposure parameters of intraoral radiography in adults were 60kV, 6mA, and 0.23 seconds and those in 12-year-old children 60kV, 6mA, and 0.16 seconds and those in 6-year-old children 60kV, 6mA, and 0.15 seconds. The median exposure parameters of panoramic radiography in adults were 74kV, 10mA, and 13.6 seconds and those in 12-yearold children 67kV, 10mA, and 13.2 seconds and those in 6-year-old children 67kV, 8mA, and 12.0 seconds. Conclusion : As the national DRLs for intraoral radiography and panoramic radiography in Korea, we recommended 1.5 mGy and 227 mGy cm2 for adults, 1.2 mGy and 175 mGy cm2 for 12-year-old children, and 1.0 mGy and 163 mGy cm2 for 6-year-old children, respectivelyope

Progressive Hemifacial Atrophy After Implant Placement in Patients Taking Immunosuppressive Agents

Progressive hemifacial atrophy (PHA) is a rare disorder characterized by acquired unilateral facial atrophy. This disease mainly affects the skin and the craniofacial tissue below forehead. It also involves dermatomes of the fifth cranial nerve. Atrophy of subcutaneous tissue, fat, muscle and osseocartilaginous structures were seen. It resulted in a sunken hemifacial appearance. Although epidermal cutaneous tissue was minimally involved, the tongue, gingiva, teeth, and palate may also be affected. The purpose of this study is to report a case of progressive hemifacial atrophy in a patient taking immunosuppressive drugs after implant and sinus graft surgery.ope

Alveolar bone height according to the anatomical relationship between the maxillary molar and sinus

Purpose: The aim of this study was to investigate the available alveolar bone height between the maxillary molars and the sinus floor according to their anatomical relationship using cone-beam computed tomographic (CBCT) images. Methods: A total of 752 maxillary first (M1) and second molars (M2) on CBCT scans of 188 patients were selected. First, each maxillary molar was categorized as type 1, 2, 3, or 4 according to the relationship of the molar root with the maxillary sinus floor. The frequency distribution of each type was analyzed. Second, the shortest vertical distance (VD) of each molar was measured from the furcation midpoints of the roots to the lowest point of the sinus floor by 2 observers. Intraclass correlation coefficients and the t-test were calculated for the VD measurements. Results: For M1, type 3 was the most frequent, followed by type 2. For M2, type 3 was the most common, followed by type 1. The VD measurements of type 1 were 9.51±3.68 mm and 8.07±2.73 mm for M1 and M2, and those of type 3 were 3.70±1.52 mm and 4.03±1.53 mm for M1 and M2, respectively. The VD measurements of M2 were significantly higher in female patients than in male patients. Conclusions: Type 3 was the most frequent anatomical relationship in the maxillary molars, and showed the lowest alveolar bone height. This information will help clinicians to prevent complications related to the maxillary sinus during maxillary molar treatment and to predict the available bone height for immediate implant planningope

Radiomics approach to the condylar head for legal age classification using cone-beam computed tomography: A pilot study

Legal age estimation of living individuals is a critically important issue, and radiomics is an emerging research field that extracts quantitative data from medical images. However, no reports have proposed age-related radiomics features of the condylar head or an age classification model using those features. This study aimed to introduce a radiomics approach for various classifications of legal age (18, 19, 20, and 21 years old) based on cone-beam computed tomography (CBCT) images of the mandibular condylar head, and to evaluate the usefulness of the radiomics features selected by machine learning models as imaging biomarkers. CBCT images from 85 subjects were divided into eight age groups for four legal age classifications: ≤17 and ≥18 years old groups (18-year age classification), ≤18 and ≥19 years old groups (19-year age classification), ≤19 and ≥20 years old groups (20-year age classification) and ≤20 and ≥21 years old groups (21-year age classification). The condylar heads were manually segmented by an expert. In total, 127 radiomics features were extracted from the segmented area of each condylar head. The random forest (RF) method was utilized to select features and develop the age classification model for four legal ages. After sorting features in descending order of importance, the top 10 extracted features were used. The 21-year age classification model showed the best performance, with an accuracy of 91.18%, sensitivity of 80%, and specificity of 95.83%. Radiomics features of the condylar head using CBCT showed the possibility of age estimation, and the selected features were useful as imaging biomarkers.ope

Clinical application of panoramic radiography With multi-layer imaging software : Case reports

Panoramic radiography is widely used as a primary radiological diagnosis in dentistry. However, due to the overlapping of anatomical structures, diagnostic capability of panoramic radiography is limited. Recently, panoramic machine equipped with various image processing software has been introduced to improve the diagnostic capability. This study aims to introduce panoramic equipment with multi-layer imaging software that can provide 41 images from anterior to posterior in region of interest, and to report in various clinical applications.ope

Bony window approach for a traumatic bone cyst on the mandibular condyle: a case report with long-term follow-up

Traumatic bone cyst (TBC) occurs preferentially on the mandibular symphysis and body, but rarely on the mandibular condyle. When TBC occurs in the condylar area, it can usually be related with or misdiagnosed as a temporomandibular joint disorder. A 15-year-old female patient visited the Temporomandibular Joint Clinic with a 5-year history of pain and noise localized in the left temporomandibular joint. On imaging, a well demarked oval-shaped radiolucent lesion was observed on the left condyle head. The patient underwent cyst enucleation and repositioning of the bony window on the lateral cortex of the affected condyle head under the impression of subchondral cyst or TBC; however, no cystic membrane was found. The bone defect resolved and showed no recurrence on the serial radiographic postoperative follow-up for 43 months after surgery.ope

Reproducibilities of cephalometric measurements of three-dimensional CT images reconstructed in the personal computer

PURPOSE : The purpose of this study was to report the reproducibility of intra-observer and inter-observer consistency of cephalometric measurements using three-dimensional (3D) computed tomography (CT), and the degree of difference of the cephalometric measurements. MATERIALS AND METHODS : CT images of 16 adult patients with normal class I occlusion were sent to personal computer and reconstructed into 3D images using V-Works 3.5TM (Cybermed Inc., Seoul, Korea). With the internal program of V-Works 3.5TM, 12 landmarks on regular cephalograms were transformed into 21 analytic categories and measured by 2 observers and in addition, one of the observers repeated their measurements. Intra-observer difference was calculated using paired t-test, and inter-observer by two sample test. RESULTS : There were significant differences in the intra-observer measurements (p<0.05) in four of the categories which included ANS-Me, ANS-PNS, Cdl-Go (Lt), GoL-GoR, but with the exception of Cdl-Go (Lt), ZmL-ZmR, Zyo-Zyo, the average differences were within 2 mm of each other. The inter-observer observations also showed significant differences in the measurements of the ZmL-ZmR and Zyo-Zyo categories (p<0.05). With the exception of the Cdl-Me (Rt), ZmL-ZmR, Zyo-Zyo categories, the average differences between the two observers were within 2 mm, but the ZmL-ZmR and Zyo-Zyo values differed greatly with values of 8.10 and 19.8 mm respectively. CONCLUSION : In general, 3D CT images showed greater accuracy and reproducibility, with the exception of suture areas such as Zm and Zyo, than regular cephalograms in orthodontic measurements, showing differences of less than 2 mm, therefore 3D CT images can be useful in cephalometric measurements and treatment planning.ope

Analysis of three-dimensional imaging findings and clinical symptoms in patients with temporomandibular joint disorders

Background: The purpose of this study was to analyze cone-beam computed tomography (CBCT) and magnetic resonance imaging (MRI) findings in temporomandibular joint disorder (TMD) patients and to comprehensively assess the relationships between these imaging findings and clinical symptoms. Methods: A total of 754 temporomandibular joints (TMJs) in 377 patients with clinical symptoms of TMD who underwent both CBCT and MRI examinations were retrospectively reviewed. Clinical symptoms included TMJ pain, TMJ sound, and limitation of mouth opening. Oral radiologists evaluated osseous changes of the condylar head on CBCT, as well as the disc configuration, internal derangement, and joint effusion on MRI. The frequency of CBCT and MRI findings and the mean and standard deviation of age were analyzed. Logistic regression analysis was used to identify associations between these imaging findings and clinical symptoms using SPSS version 25.0 for Windows (IBM Corp., Armonk, NY, USA). The model fit was evaluated using the Hosmer and Lemeshow test. Results: TMD patients consisted of 294 females and 83 males, and the age group of 20-39 accounted for 47.2% of the patients. Normal findings regarding osseous changes of the condylar head on CBCT were found in 65.1% of the patients. On MRI, a change in disc configuration was found in 54.9% of the patients, internal derangement in 62.6%, and joint effusion in 46.0%. TMJ pain was significantly associated with sclerosis [odds ratio (OR): 3.81], disc displacement without reduction (DDWOR) (OR: 3.22), grade 2 joint effusion (OR: 2.33), and grade 3 joint effusion (OR: 5.54). TMJ sound was significantly associated with disc displacement with reduction (DDWR) (OR: 3.04), DDWOR (OR: 2.50), grade 2 joint effusion (OR: 2.37), and grade 3 joint effusion (OR: 3.23). Limitation of mouth opening was significantly associated with flattened disc configuration (OR: 2.08), folded disc configuration (OR: 2.30), and grade 3 joint effusion (OR: 2.85). Conclusions: CBCT findings had little to do with clinical symptoms. In contrast, MRI findings, including disc configuration, internal derangement, and joint effusion, were associated with clinical symptoms. These results suggest that MRI should be recommended over CBCT for the proper diagnosis of TMD patients.ope

Performance comparison of three deep learning models for impacted mesiodens detection on periapical radiographs

This study aimed to develop deep learning models that automatically detect impacted mesiodens on periapical radiographs of primary and mixed dentition using the YOLOv3, RetinaNet, and EfficientDet-D3 algorithms and to compare their performance. Periapical radiographs of 600 pediatric patients (age range, 3-13 years) with mesiodens were used as a training and validation dataset. Deep learning models based on the YOLOv3, RetinaNet, and EfficientDet-D3 algorithms for detecting mesiodens were developed, and each model was trained 300 times using training (540 images) and validation datasets (60 images). The performance of each model was evaluated based on accuracy, sensitivity, and specificity using 120 test images (60 periapical radiographs with mesiodens and 60 periapical radiographs without mesiodens). The accuracy of the YOLOv3, RetinaNet, and EfficientDet-D3 models was 97.5%, 98.3%, and 99.2%, respectively. The sensitivity was 100% for both the YOLOv3 and RetinaNet models and 98.3% for the EfficientDet-D3 model. The specificity was 100%, 96.7%, and 95.0% for the EfficientDet-D3, RetinaNet, and YOLOv3 models, respectively. The proposed models using three deep learning algorithms to detect mesiodens on periapical radiographs showed good performance. The EfficientDet-D3 model showed the highest accuracy for detecting mesiodens on periapical radiographs.ope

Efficacy of corticosteroid ductal irrigation in acute salivary gland inflammation induced in a rat model

Purpose This study aimed to compare the therapeutic effects of corticosteroid irrigations and normal saline irrigations in the early inflammatory state of the salivary gland. Materials and Methods Adult male Wistar rats were divided into experimental (n=6) and control (n=3) groups. Inflammation was induced in the experimental subjects on both sides of the submandibular gland with ligation. After 14 days, both sides of the glands were de-ligated and retroductal irrigation using saline (n=3) and a corticosteroid (n=3) was performed on the left sides only. The controls (n=3) were used to normalize the gland state for the effects of diet and aging. Magnetic resonance imaging was performed to confirm inflammation and post-irrigation gland recovery by measuring relative signal intensity (SI). The glands were excised for histological examination. Results All experimental animals showed inflamed glands with increased SI and subsequent recovery of the gland with decreased SI to varying degrees. The SI of the controls showed no significant changes during the overall period. The mean SI change of the irrigated gland was higher than that of the non-irrigated side, without a significant difference. The corticosteroid-irrigated glands showed a greater change in SI than that of the saline-irrigated glands. Histology revealed that inflammation was not observed in most of the irrigated glands, while mild to moderate quantities inflammatory cells were found in non-irrigated glands. Conclusion Corticosteroid irrigation mitigated the early stages of salivary gland inflammation more effectively than normal saline.ope