Publications by authors named "Won Jin Yi"

The aim of this study was to propose a novel method to identify individuals by recognizing dentition change, along with human identification process using deep learning. Recent and past images of adults aged 20-49 years with more than two dental panoramic radiographs (DPRs) were assumed as postmortem (PM) and antemortem (AM) images, respectively. The dataset contained 1,029 paired PM-AM DPRs from 2000 to 2020.

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The aim of this study is to propose and evaluate a novel method for measuring the central ray direction and detecting the rotation centre of panoramic radiography using the panorama phantom. To determine the central ray direction, 2 points passing through the same x-coordinate in a panoramic radiograph were identified and connected. The angles formed by the central ray with the midline and the angle to the arch form were measured using mathematical calculations.

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Background: In cases where oral squamous cell carcinoma (OSCC) invades the jawbone, clinicians frequently observe abnormal attenuation on computed tomography (CT) and pathologic signal intensity (SI) on magnetic resonance (MR) imaging of the affected underlying bone marrow. This study introduced a concept of "underlying bone change" to examine its association with clinicopathological features and prognosis of OSCC, as well as its correlation with medullary invasion.

Materials And Methods: We enrolled 93 consecutive patients diagnosed with OSCC, who underwent mandibulectomy between 2010 and 2016.

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Malignant melanoma of the parotid gland is an unusual tumor in the head and neck region, and most parotid melanoma is reported as a metastatic lesion of cutaneous malignant melanoma. We report a case of primary malignant melanoma arising in the parotid gland duct with diagnostic challenge. The patient was a 68-year-old man who complained of repeated right facial swelling that presented 3 months prior.

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Stroke is one of the major causes of death worldwide, and is closely associated with atherosclerosis of the carotid artery. Panoramic radiographs (PRs) are routinely used in dental practice, and can be used to visualize carotid artery calcification (CAC). The purpose of this study was to automatically and robustly classify and segment CACs with large variations in size, shape, and location, and those overlapping with anatomical structures based on deep learning analysis of PRs.

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Sex determination is essential for identifying unidentified individuals, particularly in forensic contexts. Traditional methods for sex determination involve manual measurements of skeletal features on CBCT scans. However, these manual measurements are labor-intensive, time-consuming, and error-prone.

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Medication-related osteonecrosis of the jaw (MRONJ) poses a challenging form of osteomyelitis in patients undergoing antiresorptive therapies in contrast to conventional osteomyelitis. This study aimed to compare the clinical and radiological features of MRONJ between patients receiving low-dose medications for osteoporosis and those receiving high-dose medications for oncologic purposes. The clinical, panoramic radiographic, and computed tomography data of 159 patients with MRONJ (osteoporotic group, n = 120; oncologic group, n = 39) who developed the condition after using antiresorptive medications for the management of osteoporosis or bone malignancy were analyzed.

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Article Synopsis
  • - The study aimed to develop a deep-learning model for accurately identifying the mandibular canal in dental panoramic radiographs, utilizing a large dataset of 2,100 images from three different imaging machines.
  • - Researchers used convolutional neural networks (CNNs) with U-Net architecture for automated segmentation, training multiple networks on various combinations of the image data and evaluating their performance with a test dataset.
  • - The best-performing network, trained on data from all three machines, achieved impressive metrics, including 90.6% precision and 88.9% Dice similarity coefficient, highlighting the effectiveness of the CNN approach and the importance of radiograph characteristics in deep learning development.
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Article Synopsis
  • ForensicNet is a multi-task deep learning network designed to automatically estimate sex and chronological age from panoramic radiographs, improving efficiency in forensic investigations compared to traditional manual methods.
  • The study utilized a dataset of 13,200 images, covering various sex and age ranges, to train the network and mitigate data bias.
  • Results showed ForensicNet achieved high accuracy in both age and sex estimation, demonstrating significant performance improvements through its attention branches for analyzing anatomical features.
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Objectives: The purpose of this study is to investigate the morphological changes that occur when mesiodens is located within the nasopalatine canal, as well as clinical characteristics.

Methods: Clinical records and CT images of patients who had mesiodens in the nasopalatine canal were retrospectively analysed. In addition to demographic information, clinical symptoms and complications associated with extraction of mesiodens were recorded.

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Objectives: This study aimed to develop a robust and accurate deep learning network for detecting the posterior superior alveolar artery (PSAA) in dental cone-beam CT (CBCT) images, focusing on the precise localization of the centre pixel as a critical centreline pixel.

Methods: PSAA locations were manually labelled on dental CBCT data from 150 subjects. The left maxillary sinus images were horizontally flipped.

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Purpose: The objective of this study was to propose a method for developing a clinical phantom to reproduce various diseases that are clinically prevalent in the field of dentistry. This could facilitate diverse clinical research without unnecessarily exposing patients to radiation.

Material And Methods: This study utilized a single dry skull, which was visually and radiographically examined to evaluate its condition.

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Article Synopsis
  • This study looked at how well a special computer program called a deep convolutional neural network (DCNN) can find and classify two types of cysts in mouth x-rays.
  • Researchers used 1,209 x-rays, dividing them into groups for training and testing. They tested different DCNN models to see which one performed the best.
  • The best model, EfficientDet-D3, was very accurate and outperformed general dentists, showing a lot of potential for helping in medical situations.
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For virtual surgical planning in orthognathic surgery, marking tooth landmarks on CT images is an important procedure. However, the manual localization procedure of tooth landmarks is time-consuming, labor-intensive, and requires expert knowledge. Also, direct and automatic tooth landmark localization on CT images is difficult because of the lower resolution and metal artifacts of dental images.

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Background: The purpose of this study was to compare the segmentation performances of the 2D, 2.5D, and 3D networks for maxillary sinuses (MSs) and lesions inside the maxillary sinus (MSL) with variations in sizes, shapes, and locations in cone beam CT (CBCT) images under the same constraint of memory capacity.

Methods: The 2D, 2.

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Background: The success of cephalometric analysis depends on the accurate detection of cephalometric landmarks on scanned lateral cephalograms. However, manual cephalometric analysis is time-consuming and can cause inter- and intra-observer variability. The purpose of this study was to automatically detect cephalometric landmarks on scanned lateral cephalograms with low contrast and resolution using an attention-based stacked regression network (Ceph-Net).

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The purpose of this study was to automatically classify the three-dimensional (3D) positional relationship between an impacted mandibular third molar (M3) and the inferior alveolar canal (MC) using a distance-aware network in cone-beam CT (CBCT) images. We developed a network consisting of cascaded stages of segmentation and classification for the buccal-lingual relationship between the M3 and the MC. The M3 and the MC were simultaneously segmented using Dense121 U-Net in the segmentation stage, and their buccal-lingual relationship was automatically classified using a 3D distance-aware network with the multichannel inputs of the original CBCT image and the signed distance map (SDM) generated from the segmentation in the classification stage.

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Article Synopsis
  • Fibrodysplasia ossificans progressiva is a rare genetic disorder that causes abnormal bone growth in muscles and connective tissues, notably affecting areas like the head and neck, though this is less common.
  • The report discusses two specific cases: one patient had difficulty opening their mouth due to ossification in the lateral pterygoid muscle, while another experienced limited neck movement from ossification in the platysma muscle.
  • Clinicians should consider this condition when patients present with restricted mouth or neck movement and radiological signs of abnormal bone growth, and dentists should be cautious about invasive procedures for these individuals.
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The nasal cavity is an important landmark when considering implant insertion into the anterior region of the maxillary arch. The perforation of implants into the nasal cavity may cause complications, such as implant migration, inflammation, or changes in nasal airflow; thus, precise assessment of the nasal cavity is mandatory.Three cases of nasal cavity perforation by dental implants are presented, including one case of implant fixture migration into the nasal cavity.

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The bone mineral density (BMD) measurement is a direct method of estimating human bone mass for diagnosing osteoporosis, and performed to objectively evaluate bone quality before implant surgery in dental clinics. The objective of this study was to validate the accuracy and reliability of BMD measurements made using quantitative cone-beam CT (CBCT) image based on deep learning by applying the method to clinical data from actual patients. Datasets containing 7500 pairs of CT and CBCT axial slice images from 30 patients were used to train a previously developed deep-learning model (QCBCT-NET).

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The objective of this study was to automatically classify surgical plans for maxillary sinus floor augmentation in implant placement at the maxillary posterior edentulous region using a 3D distance-guided network on CBCT images. We applied a modified ABC classification method consisting of five surgical approaches for the deep learning model. The proposed deep learning model (SinusC-Net) consisted of two stages of detection and classification according to the modified classification method.

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Nodular fasciitis (NF) is a benign myofibroblastic proliferation that grows very rapidly, mimicking a sarcoma on imaging. It is treated by local excision, and recurrence has been reported in only a few cases, even when excised incompletely. The most prevalent diagnoses of temporomandibular joint (TMJ) masses include synovial chondromatosis, pigmented villonodular synovitis, and sarcomas.

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Cone-beam CT (CBCT) is widely used in dental clinics but exhibits limitations in assessing soft tissue pathology because of its lack of contrast resolution and low Hounsfield Units (HU) quantification accuracy. We aimed to increase the image quality and HU accuracy of CBCTs while preserving anatomical structures. We generated CT-like images from CBCT images using a patchwise contrastive learning-based GAN model.

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Article Synopsis
  • Convolutional neural networks (CNNs) are emerging as a powerful tool in medical research, particularly for early disease detection and diagnosis, which is the focus of this study on apical lesion segmentation from panoramic radiographs.
  • The research involved analyzing 1000 panoramic images of apical lesions, dividing them into training, validation, and test datasets, and assessing performance using precision, recall, and F1-score metrics.
  • The results showed that the deep CNN algorithm (U-Net) effectively segmented a majority of apical lesions, achieving high F1-scores (0.828, 0.815, and 0.742) at various thresholds, highlighting its potential in medical imaging applications.
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