• Journal of the Korean Association of Oral and Maxillofacial Surgeons
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• v.37 no.1
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• pp.54-61
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• 2011

Introduction: Bisphosphonates is used widely for the treatment of the Paget's disease, multiple myeloma, bone metastases of malignant tumors with the prevention of pain and their pathological fracture. However, it was recently suggested that bisphosphonates related osteonecrosis of the jaw (BRONJ) is a side effect of bisphosphonate use. Materials and Methods: Twenty-four individuals, who were referred to the Department of Oral and Maxillofacial surgery, Dankook University Dental Hospital, were selected from those who had exposed bone associated with bisphosphonates from January, 2005 to December, 2009 according to the criteria of American Association of Oral and Maxillofacial Surgeons (AAOMS) for BRONJ. The patients group consisted of 7 males and 17 females between the age of 46 to 78 years (average 61.8 years). Each patient had panoramic imaging, computed tomography (CT), whole body bone scanning performed for a diagnosis and biopsy sampling from the necrotizing tissue. C-terminal cross-linking telopeptide of type I collagen (CTX) level of patients who had undergone surgical intervention was measured 7 days before surgery. Results: The main cause of bone exposure was post-extraction (15), chronic periodontitis (4), persistent irritation of the denture (3). Twenty people had undergone BRONJ treatment for two to eight months except for 4 people who had to maintain the bisphosphonates treatment to prevent a metastasis and bone trabecular pain with medical treatment. When the bisphosphonate treatment was suspended at least for 3 months and followed up according to the AAOMS protocols, the exposed necrotizing bones were found to be covered by soft tissue. Conclusion: Prevention therapy, interruption of bisphophonates for at least 3 months and cooperation with the physician for conservative treatment are the essential for treating BRONJ patient with high risk factors. The CTX level of BRONJ patients should be checked before undergoing surgical intervention. Surgical treatments should be delayed in the case of a CTX level <150 pg/mL.

• Imaging Science in Dentistry
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• v.38 no.1
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• pp.17-22
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• 2008

Purpose: It is important to determine the bucco-lingual inclination of implants on radiographs before the implant surgery. The purpose of this study was to compare the buccolingual inclination in alveolar bone and the tooth with dental cone beam CT and to prepare the standard for the buccolingual inclination of implant. Materials and Methods: Axial, panoramic, and buccolingually sectioned images of 80 implant cases with stent including straight marker using CB $Mercuray^{TM}$ (Hitachi, Japan) were evaluated. The comparison of the buccolingual inclination of remained alveolar bone with the tooth and the marker on butcolingually sectioned views was performed statistically. Results: The average buccolingual inclination of remained alveolar bone and tooth was $82.8{\pm}4.6^{\circ}\;and\;85.8{\pm}4.7^{\circ}$ (p<0.05, r=0.96) at the 1st molar area and $76.4{\pm}1.7^{\circ}\;and\;82.7{\pm}1.7^{\circ}$ respectively (p>0.05, r=0.12) at the 2nd premolar area in upper jaw. The average buccolingua1 inclination of remained alveolar bone and tooth was $81.3{\pm}8.3^{\circ}\;and\;87.5{\pm}6.3^{\circ}$ (p>0.05, r=0.85) at the lower 2nd premolar area and $94.3{\pm}6.6^{\circ}\;and\;93.3{\pm}7.2^{\circ}$ respectively (p>0.05, r=0.91) at the 1st molar area in lower jaw. The inclinations of markers were very different from those of remained bone at the most of areas except the upper 2nd premolar area (r=0.79). Conclusion: We recommend dental CBCT analysis for determining the buccolingual inclination of dental implant, because of significant difference, in average, between the bucco1ingual inclination of remained alveolar bone and tooth.

• Imaging Science in Dentistry
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• v.43 no.4
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• pp.227-233
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• 2013

Purpose: This study was performed to analyze human maxillary and mandibular trabecular bone using the data acquired from micro-computed tomography (micro-CT), and to characterize the site-specific microstructures of trabeculae. Materials and Methods: Sixty-nine cylindrical bone specimens were prepared from the mandible and maxilla. They were divided into 5 groups by region: the anterior maxilla, posterior maxilla, anterior mandible, posterior mandible, and mandibular condyle. After the specimens were scanned using a micro-CT system, three-dimensional microstructural parameters such as the percent bone volume, bone specific surface, trabecular thickness, trabecular separation, trabecular number, structure model index, and degrees of anisotropy were analyzed. Results: Among the regions other than the condylar area, the anterior mandibular region showed the highest trabecular thickness and the lowest value for the bone specific surface. On the other hand, the posterior maxilla region showed the lowest trabecular thickness and the highest value for the bone specific surface. The degree of anisotropy was lowest at the anterior mandible. The condyle showed thinner trabeculae with a more anisotropic arrangement than the other mandibular regions. Conclusion: There were microstructural differences between the regions of the maxilla and mandible. These results suggested that different mechanisms of external force might exist at each site.

• Journal of the Korean Association of Oral and Maxillofacial Surgeons
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• v.46 no.3
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• pp.174-182
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• 2020

Objectives: Joint injuries frequently lead to progressive joint degeneration that causes articular disc derangement, joint inflammation, and osteoarthritis. Such arthropathies that arise after trauma are defined as post-traumatic arthritis (PTA). Although PTA is well recognized in knee and elbow joints, PTA in the temporomandibular joint (TMJ) has not been clearly defined. Interestingly, patients experiencing head and neck trauma without direct jaw fracture have displayed TMJ disease symptoms; however, definitive diagnosis and treatment options are not available. This study will analyze clinical aspects of PTA in TMJ and their treatment outcomes after joint arthrocentesis and lavage. Materials and Methods: Twenty patients with history of trauma to the head and neck especially without jaw fracture were retrospectively studied. Those patients developed TMJ disease symptoms and were diagnosed by computed tomography or magnetic resonance imaging. To decrease TMJ discomfort, arthrocentesis and lavage with or without conservative therapy were applied, and efficacy was evaluated by amount of mouth opening and pain scale. Statistical differences between pre- and post-treatment values were evaluated by Wilcoxon signed-rank test. Results: Patient age varied widely between 20 and 80 years, and causes of trauma were diverse. Duration of disease onset was measured as 508 post-trauma days, and 85% of the patients sought clinic visit within 2 years after trauma. In addition, 85% of the patients showed TMJ disc derangement without reduction, and osteoarthritis was accompanied at the traumatized side or at both sides in 40% of the patients. After arthrocentesis or lavage, maximal mouth opening was significantly increased (28-44 mm on average, P<0.001) and pain scale was dramatically decreased (7.8-3.5 of 10, P<0.001); however, concomitant conservative therapy showed no difference in treatment outcome. Conclusion: The results of this study clarify the disease identity of PTA in TMJ and suggest early diagnosis and treatment options to manage PTA in TMJ.

• The korean journal of orthodontics
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• v.50 no.3
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• pp.157-169
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• 2020

Objective: The aim of this retrospective study was to evaluate the pre- and postsurgical bone densities at alveolar and extra-alveolar sites following two-jaw orthognathic surgery. Methods: The sample consisted of 10 patients (mean age, 23.2 years; range, 18.0-27.8 years; 8 males, 2 females) who underwent two-jaw orthognathic surgery. A three-dimensional imaging program (Invivo 5) was used with multidetector computed tomography images taken pre- and postoperatively (obtained 32.3 ± 6.0 days before surgery and 5.8 ± 2.6 days after surgery, respectively) for the measurement of bone densities at the following sites: (1) alveolar bone in the maxilla and mandible, (2) extra-alveolar sites, such as the top of the head, menton (Me), condyle, and the fourth cervical vertebrae (C4). Results: When pre- and postsurgical bone densities were compared, an overall tendency of decrease in bone density was noted. Statistically significant reductions were observed in the densities of cancellous bone at several areas of the maxillary alveolar bone; cortical and cancellous bone in most areas of the mandibular alveolar bone; cortical bone in Me; and cancellous bone in C4. There was no statistically significant difference in bone density in relation to the depth of the alveolar bone. In a comparison of the bone densities between groups with and without genioplasty, there was almost no statistically significant difference. Conclusions: Accelerated tooth movement following orthognathic surgery may be confirmed with reduced bone density. In addition, this study could offer insights into bone metabolism changes following orthognathic surgery, providing direction for further investigations in this field.

• Progress in Medical Physics
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• v.26 no.3
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• pp.160-167
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• 2015

Radiation exposure from medical diagnostic imaging procedures to patients is one of the most significant interests in diagnostic x-ray system. A miniature x-ray intraoral tube was developed for the first time in the world which can be inserted into the mouth for imaging. Dose evaluation should be carried out in order to utilize such an imaging device for clinical use. In this study, dose evaluation of the new x-ray unit was performed by 1) using a custom made in vivo Pig phantom, 2) determining exposure condition for the clinical use, and 3) measuring patient dose of the new system. On the basis of DRLs (Diagnostic Reference Level) recommended by KDFA (Korea Food & Drug Administration), the ESD (Entrance Skin Dose) and DAP (Dose Area Product) measurements for the new x-ray imaging device were designed and measured. The maximum voltage and current of the x-ray tubes used in this study were 55 kVp, and 300 mA. The active area of the detector was $72{\times}72mm$ with pixel size of $48{\mu}m$. To obtain the operating condition of the new system, pig jaw phantom images showing major tooth-associated tissues, such as clown, pulp cavity were acquired at 1 frame/sec. Changing the beam currents 20 to $80{\mu}A$, x-ray images of 50 frames were obtained for one beam current with optimum x-ray exposure setting. Pig jaw phantom images were acquired from two commercial x-ray imaging units and compared to the new x-ray device: CS 2100, Carestream Dental LLC and EXARO, HIOSSEN, Inc. Their exposure conditions were 60 kV, 7 mA, and 60 kV, 2 mA, respectively. Comparing the new x-ray device and conventional x-ray imaging units, images of the new x-ray device around teeth and their neighboring tissues turn out to be better in spite of its small x-ray field size. ESD of the new x-ray device was measured 1.369 mGy on the beam condition for the best image quality, 0.051 mAs, which is much less than DRLs recommended by IAEA (International Atomic Energy Agency) and KDFA, both. Its dose distribution in the x-ray field size was observed to be uniform with standard deviation of 5~10 %. DAP of the new x-ray device was $82.4mGy*cm^2$ less than DRL established by KDFA even though its x-ray field size was small. This study shows that the new x-ray imaging device offers better in image quality and lower radiation dose compared to the conventional intraoral units. In additions, methods and know-how for studies in x-ray features could be accumulated from this work.

• Imaging Science in Dentistry
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• v.43 no.3
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• pp.163-169
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• 2013

Purpose: Tonsilloliths are calcifications found in the crypts of the palatal tonsils and can be detected on routine panoramic examinations. This study was performed to highlight the benefits of cone-beam computed tomography (CBCT) in the diagnosis of tonsilloliths appearing bilaterally on panoramic radiographs. Materials and Methods: The sample group consisted of 7 patients who had bilateral radiopaque lesions at the area of the ascending ramus on panoramic radiographs. CBCT images for every patient were obtained from both sides of the jaw to determine the exact locations of the lesions and to rule out other calcifications. The calcifications were evaluated on the CBCT images using Ez3D2009 software. Additionally, the obtained images in DICOM format were transferred to ITK SNAP 2.4.0 pc software for semiautomatic segmentation. Segmentation was performed using contrast differences between the soft tissues and calcifications on grayscale images, and the volume in mm3 of the segmented three dimensional models were obtained. Results: CBCT scans revealed that what appeared on panoramic radiographs as bilateral images were in fact unilateral lesions in 2 cases. The total volume of the calcifications ranged from 7.92 to $302.5mm^3$. The patients with bilaterally multiple and large calcifications were found to be symptomatic. Conclusion: The cases provided the evidence that tonsilloliths should be considered in the differential diagnosis of radiopaque masses involving the mandibular ramus, and they highlight the need for a CBCT scan to differentiate pseudo- or ghost images from true bilateral pathologies.

• Imaging Science in Dentistry
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• v.47 no.4
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• pp.255-259
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• 2017

Purpose: Underlying bone sclerosis is frequently observed in clinical settings when oral squamous cell carcinoma (OSCC) invades the jaw bone. The aim of this study was to assess the prevalence and characteristics of underlying bone sclerosis in patients with OSCC. Materials and Methods: We retrospectively reviewed the computed tomographic (CT) images of 131 patients who underwent mandibulectomy between January 2012 and December 2015 to treat OSCC. The presence, degree, and extent of underlying bone sclerosis were assessed on CT images and correlated with the following imaging patterns of bone invasion: cortical invasion, medullary invasion with a smooth margin, and medullary invasion with an irregular margin. The chi-square test was used to determine the relationships between the variables. Results: The prevalence of underlying bone sclerosis on CT images was 70.1% (47 of 67). The prevalence was 85.7% (42 of 49) in patients with medullary invasion, but it was 27.8% (5 of 18) in patients with only cortical invasion, indicating a significant increase in the prevalence of underlying bone sclerosis in patients with medullary invasion (P<.05). Aggressive patterns of bone invasion were associated with increases in the degree and extent of the underlying bone sclerosis(P<.05). Conclusion: More than two-thirds of OSCC cases with bone invasion showed underlying bone sclerosis. On CT images, reactive sclerosis in the remaining margin of the alveolar bone should not be used as the primary means to differentiate periodontal inflammatory lesions from those resulting from OSCC.

• Journal of Periodontal and Implant Science
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• v.46 no.4
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• pp.234-243
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• 2016

Purpose: Immediate loading of dental implants has been proved to be feasible in partially edentulous jaws. The purpose of this retrospective investigation was to assess the feasibility of immediately loading dental implants in fully edentulous jaws. Methods: A total of 24 patients aged between 53 and 89 years received a total of 154 implants in their edentulous maxillae or mandibles. Among the implants, 45 were set in fresh extracted sockets and 109 in consolidated alveolar bones. The implants were provisionally managed with chair-side made provisional resin bridges and exposed to immediate loading. Implants were followed up for 1-8 years, including radiographic imaging. Marginal bone levels were evaluated based on radiographic imaging. Results: A total of 148 out of the 154 implants survived over the follow-up period of 1 to 8 years, giving a survival rate of 96%. The time or region of the implantation, the pre-implant augmentation, and the length and diameter of the implants had no statistically significant influence on the survival or the success rate. The marginal bone level remained stable with only minimal loss of 0.3 mm after 60 months of loading. Conclusions: Within the limitations of this study, immediate loading is feasible for dental implants in edentulous jaws.

• The Journal of the Korean dental association
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• v.52 no.10
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• pp.623-632
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• 2014

The facial asymmetries include maxillary, mandibular, and chin asymmetries, although the most common deformity is primarily in the mandible. Common causes of this type of asymmetry can include asymmetric growth of the condyle or the mandible. In these patients, the location of the Me would be deviated to the shorter side because of the asymmetric growth of the mandible, and, commonly, the maxillary occlusal plane would be tilted toward the deviated side because the maxilla likely grows asymmetrically according to the pattern of asymmetric mandibular growth. Three-dimensional CT images are ideal for evaluating the size and location of anatomic structures, and such reconstructed images allow the use of software that can show anatomic structures from numerous angles, allowing actual measurements of distances and angles without problems of magnification, distortion, or superimposition caused by 2-dimensional imaging. In the present study using 3D-CT imaging, the 8 parameters, including measurements of the upper midline deviation, maxillary canting in the canine and first molar regions, width of the upper arch, width of the mandible at the Go, vertical length of the ramus, inclination of the ramus, and deviation of the Me were easily measured. The dentition should be orthodontically decompensated and dental midline should ensure incisor midlines positioned in the midline of each jaw before surgical correction. Surgical correction could be considered such as canting or yawing correction in the frontal or horizontal aspect, respectively.