• The Journal of the Korean dental association
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• v.24 no.4 s.203
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• pp.345-357
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• 1986

Computerized tomography has become more widely available in numerous centers throughout the world and is now recognized in many specialities as an important diagnostic procedure. The use of computerized tomography in oral and maxillofacial surgery is discussed. It has been found to be of special value in the diagnosis and assesment of expanding and infiltrating lesions of the jaws, fracture and infections, especially in the midface, in both adults and children.

• Journal of Korean Academy of Oral and Maxillofacial Radiology
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• v.23 no.1
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• pp.159-164
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• 1993

Cystic hygroma is a special form of lymphangioma. It most often occurs in the neck of children. We observed a 14-year-old male whose chief complaint was a abnormal swelling of the right mandibular angle area. The computerized tomography showed the well-defined nonenhancing cystic mass on right submandibular gland area and anterior triangle of the neck. The histopathologic fidings exhibited the multiloculatedfluid-filled cysts, which are lined a flattened layer of endothelial cells with foci of lymphocytes found lying adjacent to the lining. After evaluation of above findings, the mass was diagnosed as a cystic hygroma in the neck.

• Journal of the Korean Association of Oral and Maxillofacial Surgeons
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• v.34 no.5
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• pp.555-561
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• 2008

Purpose: The goal of this study was to develop a technique for creating a computerized composite maxillofacial-dental model, based on point-based surface best fit algorithm and to test its accuracy. The computerized composite maxillofacial-dental model was made by the three dimensional combination of a 3-dimensional (3D) computed tomography (CT) bone model with digital dental model. Materials and Methods: This integration procedure mainly consists of following steps : 1) a reconstruction of a virtual skull and digital dental model from CT and laser scanned dental model ; 2) an incorporation of dental model into virtual maxillofacial-dental model by point-based surface best fit algorithm; 3) an assessment of the accuracy of incorporation. To test this system, CTs and dental models from 3 volunteers with cranio-maxillofacial deformities were obtained. And the registration accuracy was determined by the root mean squared distance between the corresponding reference points in a set of 2 images. Results and Conclusions: Fusion error for the maxillofacial 3D CT model with the digital dental model ranged between 0.1 and 0.3 mm with mean of 0.2 mm. The range of errors were similar to those reported elsewhere with the fiducial markers. So this study confirmed the feasibility and accuracy of combining digital dental model and 3D CT maxillofacial model. And this technique seemed to be easier for us that its clinical applicability can good in the field of digital cranio-maxillofacial surgery.

• Journal of the Korean Association of Oral and Maxillofacial Surgeons
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• v.32 no.6
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• pp.566-574
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• 2006

Purpose : This study was performed to provide an anatomical information of the mandibular ramus for the successful inferior alveolar nerve block. Three dimensional images were reconstructed from the computerized tomography (CT) and the anatomical evaluation of the mandibular ramus was done. Materials and methods : Sixty-four patients who had been taken the facial CT scans from 2000, Jan to 2003, June was selected. The patients who had the anterior or posterior teeth misssing, edentulous ridge, and jaw fracture were excepted. In the occulusal plane, the lingual surface angle (LSA) between the mid-sagittal plane and the mandibular molar lingual surface from the 2nd premolar to the 2nd molar, the inner ramal surface angle (IRSA), the maximum inner ramal surface angle (MxIRSA), and the outer ramal surface angle (ORSA) to the-mid sagittal plane were measured. The inner ramal surface angle in the ligular tip level (IRSA-L) and the outer ramal surface angle in the ligular tip level (ORSA-L), the ramal length (RL), and the anterior ramal length (ARL) were also measured in the lingular tip level. Results : In the lingular tip level, the mean IRSA-L and ORSA-L were $28.6{\pm}6.3^{\circ}$ and $17.9{\pm}4.9^{\circ}$ respectively. The larger was the IRSA, the larger was the ORSA. In the lingular tip level, the mean ramal length was 35.8${\pm}$3.4 mm. The larger was the IRSA-L, the shorter was the ramal length. On the lingular tip level, the mean anterior ramal length from anterior ramus to lingular tip was 19.6${\pm}$3.3 mm. when the ramal length was longer, the anterior ramal length was also longer. On the lingular tip level, there was positive correlation vetween the IRSA and the ORSA, negative correlation between the IRSA and the ramal length, and positive correlation between the ramal length and the lingular tip level to the anterior ramus. There was no statistical meaning of data between sex and age. Conclusion : In the clinical view of the results so far achieved, if the direction of needle is closer to posterior it is able to contact bone on lingular tip when the internal surface of ramus is wided outer.

• Journal of the Korean Association of Oral and Maxillofacial Surgeons
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• v.36 no.4
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• pp.262-269
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• 2010

Introduction: Accurate diagnosis and treatment planning are very important for orthognathic surgery. A small error in diagnosis can cause postoperative functional and esthetic problems. Pre-existing 2-dimensional (D) chephalogram analysis has a high likelihood of error due to its intrinsic and extrinsic problems. A cephalogram can also be inaccurate due to the limited anatomic points, superimposition of the image, and the considerable time and effort required. Recently, an improvement in technology and popularization of computed tomography (CT) provides patients with 3-D computer based cephalometric analysis, which complements traditional analysis in many ways. However, the results are affected by the experience and the subject of the investigator. Materials and Methods: The effects of the sources human error in 2-D cephalogram analysis and 3-D computerized tomography cephalometric analysis were compared using Simplant CMF program. From 2008 Jan to 2009 June, patients who had undergone CT, cephalo AP, lat were investigated. Results: 1. In the 3 D and 2 D images, 10 out of 93 variables (10.4%) and 11 out 44 variables (25%), respectively, showed a significant difference. 2. Landmarks that showed a significant difference in the 2 D image were the points frequently superimposed anatomically. 3. Go Po Orb landmarks, which showed a significant difference in the 3 D images, were found to be the artificial points for analysis in the 2 D image, and in the current definition, these points cannot be used for reproducibility in the 3 D image. Conclusion: Generally, 3-D CT images provide more precise identification of the traditional cephalometric landmark. Greater variability of certain landmarks in the mediolateral direction is probably related to the inadequate definition of the landmarks in the third dimension.

• Maxillofacial Plastic and Reconstructive Surgery
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• v.32 no.3
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• pp.229-235
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• 2010

Purpose: This study examined the significance of increased bone density according to time after implantation on maxilla using demographic data with CBCT and compared the bone density between before vs. after implantation using the Hounsfield index. Materials and Methods: Twenty-five implant site on maxilla were selected. Cone-beam computerized tomography (CBCT) scans were used for the analysis. The implant sites were evaluated digitally using the Hounsfield scale with EzImplant TM and the results were compared over time. Statistical data over time was carried out to determine the correlation between the recorded Hounsfield unit (HU) over time and gender difference using repeated ANOVA. Results: The bone density of implantation site over time showed an increase in the HU mean values. Immediately after implantation, bone density was significantly increased than bone density before implantation. Until 6 month follow-up, bone density showed stable increasement. There is no significant difference on gender. Conclusions: Using CBCT, bone density increased over time after implantation on maxilla. Bone density measurements using CBCT might provide an objective assessment of the bone quality as well as the correlation between bone density and stability of implant.

• Journal of International Society for Simulation Surgery
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• v.3 no.2
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• pp.84-86
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• 2016

Heterotopic ossification (HO) is the formation of mature bone in soft tissue where bone normally does not exist. Although HO is among the most common complications after orthopedic surgery, it is not familiar to oral and maxillofacial surgeons. Here we report rare cases of HO. When a patient presents atypical osseous lesions, HO as well as similar lesions such as osteoma, osteochondroma should be considered in the provisional diagnosis. Three-dimensional reconstruction of preoperative computerized tomography imaging improves surgical success.

• Journal of Yeungnam Medical Science
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• v.18 no.1
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• pp.123-137
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• 2001

Background: The purpose of this study is to evaluate the accuracy of measurements obtained from 3-dimensional computerized tomography and 3-dimensional cephalogram constructed by using the frontal and lateral cephalogram of six human dry skulls. Materials and Methods: After CT scans and each cephalograms were taken, 3-dimensional coordinates (X, Y, Z) of landmarks were obtained using computer programs. In this study, the accuracy of both methods were determined by means of 14 linear measurements compare with caliper measurements. Results: The standard deviation of landmarks of 3-dimensional CT and 3-dimensional cephalogram were 0.23 mm, and 0.30 mm in X axis, 0.27 mm and 0.25 mm in Y axis, and 0.27 mm and 0.31 mm in Z axis. In both methods, the standard deviation were less than 0.5 mm in all landmarks, and the most of landmarks showed less than 1 mm in range. Concerning the accuracy, the mean difference between 3-dimensional CT and manual measurements was 0.33 mm, and 1.13 mm between 3-dimensional cephalogram and manual measurements. The distance between RGo and LGo showed the largest difference (2.03 mm). There were highly significant, and large correlation with manual measurements in both methods (p<0.01). Conclusion: It is concluded that closeness of repeated measures to each skulls reveal the precision of both methods. Computerized tomography and cephalogram for 3-dimensional measurement of maxillofacial structure are equivalent in quality to caliper measurements.

• 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.

• 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.