• Journal of the korean academy of Pediatric Dentistry
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• v.48 no.1
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• pp.50-63
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• 2021

Microcephalic osteodysplastic primordial dwarfism type II (MOPD II) is an autosomal recessive inherited disorder form of primordial dwarfism, caused by mutations in the pericentrin gene. The purpose of the study was to examine the clinical and radiological features, physicochemical properties and microstructures of the tooth affected with MOPD II. The mandibular 2nd molar was collected from the MOPD II patient. Micro-computerized tomography, scanning electron microscopy, energy dispersive spectrometry and Vickers microhardness analysis were performed on the MOPD II and the normal control. The morphology of the MOPD II tooth appeared to have malformed pulp and root and showed a small size. The mineral density measurement showed that the MOPD II tooth had similar scores in the enamel, but lower scores in the root 1/2 and apical dentin compared to the normal control. The microhardness values were smaller in the cusp enamel, root 1/2 dentin and apical dentin of the MOPD II compared to the normal control. In this study, the dental characteristics and the physicochemical properties of a tooth affected with MOPD II were analyzed to improve understanding of the oral manifestations of the disease and to assist in proper dental treatment by identifying precautions.

• The Journal of Korea Institute of Information, Electronics, and Communication Technology
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• v.16 no.5
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• pp.331-337
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• 2023

In this paper, we propose a deep learning model to detect lumbar 3 (L3) CT images to determine the occurrence and degree of sarcopenia. In addition, we would like to propose an optimization technique that uses oversampling ratio and class weight as design parameters to address the problem of performance degradation due to data imbalance between L3 level and non-L3 level portions of CT data. In order to train and test the model, a total of 150 whole-body CT images of 104 prostate cancer patients and 46 bladder cancer patients who visited Gangneung Asan Medical Center were used. The deep learning model used ResNet50, and the design parameters of the optimization technique were selected as six types of model hyperparameters, data augmentation ratio, and class weight. It was confirmed that the proposed optimization-based L3 level extraction model reduced the median L3 error by about 1.0 slices compared to the control model (a model that optimized only 5 types of hyperparameters). Through the results of this study, accurate L3 slice detection was possible, and additionally, we were able to present the possibility of effectively solving the data imbalance problem through oversampling through data augmentation and class weight adjustment.

• Journal of the korean academy of Pediatric Dentistry
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• v.46 no.4
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• pp.400-408
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• 2019

The purpose of this study is to identify the most common canal type in primary molars and the correlation between their roots and canals. A comprehensive understanding of root canal morphology will lead to more successful root canal treatment. Computed Tomography (CT) images from 114 children (81 boys, 33 girls) aged 3 - 7 years were obtained. The locations and numbers of roots and canals were evaluated, and the relationship between root and canal parameters was determined. The most commonly observed canal morphology in primary maxillary molars were mesio-buccal, disto-buccal and palatal canal. Primary mandibular molars most frequently contain mesio-buccal, mesio-lingual, disto-buccal and distolingual canal. All the roots of the primary maxillary molars except for the mesio-buccal root, each had 1 canal while there were 2 canals observed in each root of primary mandibular molars. Without exception, all mesial roots in primary mandibular 2nd molars had 2 canals. In case when either the palatal root in a primary maxillary molar or the distal root in a primary mandibular molar was separated into 2 roots, each root seemed to have its own canal. Even though the disto-buccal and palatal roots were fused into 1 root in primary maxillary molars, this fused root had tendency to have 2 separate canals. Primary mandibular molars showed similar canal morphologies between left and right molars in the same patient, while the primary maxillary molars did not.

• Journal of the Korean Association of Oral and Maxillofacial Surgeons
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• v.38 no.1
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• pp.38-43
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• 2012

Introduction: The location of parotid gland tumors in the superficial or deep lobes can affect the time and difficulty of operations. Therefore, accurate preoperative evaluation of the tumor location is important for surgical outcomes. Materials and Methods: A total of 16 patients with parotid gland tumors and who underwent a parotidectomy between April 2003 and March 2011 were retrospectively reviewed in terms of demographic background, tumor location, surgical treatment, and treatment outcomes. Tumor location was estimated by four landmarks on contrast enhanced computerized tomography scans, which were Conn's arc, the facial nerve (FN) line, the Utrecht line, and the retromandibular vein. Tumor location was confirmed by relative position depending on the facial nerve during surgery. It was assumed positive since the tumor lies in the superficial lobe of the parotid gland, the sensitivity, specificity, positive predictive value, negative predictive value, and efficiency of each landmark were evaluated. Results: Our result revealed that the facial nerve line had a sensitivity of 83.3%, specificity of 100%, positive predictive value of 100%, negative predictive value of 71.4%, and efficiency of 87.5%. Some would be more efficient preoperative evaluation methods of the relationship of parotid gland tumors to the facial nerve than others. Conclusion: In our study, the FN line was found to be the most reliable analysis method.

• Journal of Trauma and Injury
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• v.28 no.4
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• pp.262-265
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• 2015

An arteriovenous fistula (AVF) from the renal artery following a penetrating abdominal trauma is not common. We report the case of a 19-year-old male who presented with a knife stab wound in the right upper quadrant. Due to unstable vital signs and to the protrusion of the mesentery through the stab wound, providing definite evidence of peritoneal violation, an emergent exploratory laparotomy was carried out. There were injuries at the proximal transverse mesocolon and the second portion of the duodenum, with bile leakage. There was also a mild amount of retroperitoneal hematoma near the right kidney, without signs of expansion or pulsation. The mesocolon and the duodenum were repaired. After the operation, abdominal computerized tomography (CT) was performed, which revealed contrast from the right renal artery shunting directly into the vena cava. Transcatheter arterial embolization with a coil and vascular plug was performed, and the fistula was repaired. The patient recovered completely and was discharged without complication. For further and thorough evaluation of an abdominal trauma, especially one involving the retroperitoneum, a CT scan is recommended, when possible, either prior to surgery or after surgery when the patient is stabile. Furthermore, a lateral retroperitoneal hematoma and an AVF after a penetrating trauma may not always require exploration. Sometimes, it may be safely treated non-operatively or with embolization.

• Journal of Korean Neurosurgical Society
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• v.44 no.1
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• pp.15-18
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• 2008

Objective : C2 laminar screw fixation is considered as an excellent alternative to Magerl's transfacetal approach or Harms construct for the atlantoaxial stabilization. However, to our knowledge, there is no report on the feasibility of the new approach to Korean population. We investigated morphometric parameters of the dorsal arch of the C2 to provide the quantitative data for the feasibility of laminar screw fixation. Methods : One-hundred-and-two patients' cervical computed tomography had been reconstructed and investigated on the anatomical parameters related with C2 laminar screw placement. Sixty patients were male and forty-two patients were female. Measurements included the laminar thickness and slope, spino-laminar angle, and maximal screw length. Results : Ages ranged from 20 to 81 and the mean age was 48.4. Mean laminar thickness was 5.7 mm (${\pm}1.0$) (5.8 mm in male and 5.4 mm in female). Fifty-one patients (50%) had a laminar thickness smaller than 5.5 mm at least unilaterally, therefore the patients were considered as inappropriate candidates for the laminar screw fixation in the smaller side of the laminae. Mean value of maximal length of screw was 33.3 mm (34.3 mm in male and 31.9 mm in female). Mean spino-laminar angle was $43.2^{\circ}$ and mean slope angle was $32.9^{\circ}$. Conclusion : Half of patients had inappropriate laminar profiles to accommodate a 3.5 mm screw in at least one side of the axis. The three-dimensional computed tomography reconstruction is mandatory for the preoperative assessment for the feasibility of the C2 lamina.

• Maxillofacial Plastic and Reconstructive Surgery
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• v.37
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• pp.28.1-28.7
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• 2015

Background: The aim of this study was to present three-dimensional (3D) structural characteristics of the mandible in the hemifacial microsomia. The mandible has six distinct functional units, and its architecture is the sum of balanced growth of each functional unit and surrounding matrix. Methods: In order to characterize the mandibular 3D architecture of hemifacial microsomia, we analyzed the mandibular functional units of four hemifacial microsomia patients using the 3D reconstructed computed tomography (CT) images. And we compared the functional unit size between affected and non-affected side. Results: The length of condyle and angle showed significant differences between affected and non-affected sides. However, the length of mandibular body showed insignificant differences. The size differences between affected and non-affected side were observed at the condyle, angle, and body in descending order. Conclusions: This preliminary study suggests that the main etiopathogenic units are condyle and angle in the hemifacial microsomia mandible. Further investigation with the increased number of subjects will be helpful to establish treatment modality by etiopathogenic targeting of hemifacial microsomia.

• Imaging Science in Dentistry
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• v.40 no.4
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• pp.171-178
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• 2010

Purpose : The purpose of this study is to develop a surgical stent for dental implant procedure that can be easily applied and affordable by using cone beam computerized tomography (CBCT). Materials and Methods : Aluminum, Teflon-PFA (perfluoroalkoxy), and acetal (polyoxymethylene plastic) were selected as materials for the surgical stent. Among these three materials, the appropriate material was chosen using the CBCT images. The surgical stent, which could be easily placed into an oral cavity, was designed with chosen material. CBCT images of the new surgical stent on mandible were obtained using Alphard-3030 dental CT system (Asahi Roentgen Co., Ltd., Kyoto, Japan). The point of insertion was prescribed on the surgical stent with the multiplanar reconstruction software of OnDemand3D (CyberMed Inc., Seoul, Korea). Guide holes were made at the point of insertion on the surgical stent using newly designed guide jig. CBCT scans was taken for the second time to verify the accuracy of the newly designed surgical stent. Results : Teflon-PFA showed radiologically excellent image characteristics for the surgical stent. High accuracy and reproducibility of implantation were confirmed with the surgical stent. Conclusion : The newly designed surgical stent can lead to the accurate implantation and achieve the clinically predictable result.

• Maxillofacial Plastic and Reconstructive Surgery
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• v.40
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• pp.30.1-30.6
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• 2018

Background: The purpose of the present study was to investigate the differences in the position and shape of the anterior loop of the inferior alveolar nerve (ALIAN) in relation to the growth pattern of the mandibular functional subunit. Methods: The study was conducted on 56 patients among those who had undergone orthognathic surgery at the Gangnam Severance Hospital between January 2010 and December 2015. Preoperative computerized tomography (CT) images were analyzed using the Simplant OMS software (ver.14.0 Materialise Medical, Leuven, Belgium). The anterior and inferior lengths of ALIAN (dAnt and dInf) and each length of the mandibular functional subunits were measured. The relationship between dAnt, dInf, and the growth pattern of the mandibular subunits was analyzed. Results: The length of the anterior portion of ALIAN (dAnt) reached 3.34 ± 1.59 mm in prognathism and 1.00 ± 0.97 mm in retrognathism. The length of the inferior portion of ALIAN (dInf) reached 6.81 ± 1.33 mm in prognathism and 5.56 ± 1.34 mm in retrognathism. The analysis of Pearson's correlation coefficiency on all samples showed that the lengths of functional subunits were positively correlated with the loop depth. The length of the symphysis area in prognathic patients was positively correlated with the anterior loop depth (p = 0.005). Conclusions: Both the anterior and inferior length of ALIAN are longer in prognathic patients. Especially, it seems to be associated with the growth of the symphysis area.

• Archives of Plastic Surgery
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• v.37 no.4
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• pp.375-379
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• 2010

Purpose: The nasal bone is the most frequently fractured facial bone. Discordance between the CT reading by the radiologist and the diagnosis by the plastic surgeon is not uncommon. This study examined the discordance and proposes a method for reducing the rate of discordance. Methods: The CT readings by the radiologist were compared with the diagnosis by the plastic surgeon in 716 patients with a clinically suspected nasal bone fracture. The CT reading was classified as the following: a nasal bone fracture, suspicious nasal bone fracture, old nasal bone fracture, no nasal bone fracture. The sensitivity, specificity and positive predictive value of the CT reading were calculated. Results: A nasal bone fracture was diagnosed in 646 patients by the plastic surgeon and confirmed intraoperatively. The reading of a "nasal bone fracture", "suspicious nasal bone fracture", "old nasal bone fracture" and "no nasal bone fracture" was 85.8%, 4.6%, 0.6% and 9.1% respectively. The sensitivity and specificity of the CT reading were 95.0% and 92.9%, respectively. The positive predictive value of the CT reading was 99.3%. The reading of "nasal bone fracture" that was not a nasal bone fracture clinically was 17.1% (12 of 70), and the reading of "no nasal bone fracture" or "old nasal bone fracture" that was found to be a nasal bone fracture clinically was 3.3% (21 of 646). The discordance rate between the CT reading by the radiologist and the diagnosis by the plastic surgeon was 4.6%. Conclusions: To reduce the discordance rate, we propose to hold a meeting with the plastic surgery-radiology staff to communicate the information regarding a suspicious or old nasal bone fracture.