• Journal of Korean Academy of Oral and Maxillofacial Radiology
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• v.23 no.2
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• pp.323-332
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• 1993

저자는 1988년 6월 1일부터 1993년 6월 30일까지 서울대학교병원 치과진료부에 내원하여, 병리조직학적으로 확인된 구강악안면부 악성종양환자 35명의 방사선사진 소견과 자기공명영상 소견을 비교하여 다음과 같은 결론을 얻었다. 1. 일반적인 방사선사진소견으로는 미만성의 골파괴가 15례 (42.9%), 연조직종괴의 음영이 7례 (20,0%), 부유치를 보인 경우가 3례 (8.6%), 골경화가 2례 (51.7%)로 나타났다. 2. 자기공명영상 소견은 연조직종괴가 23례 (65.7%), 골수침범이 12례(34.5%), 피질골 파괴가 14례(40.0%), 정상피질골에 골수침범이 1례 (2.9%), 지방층소실이 19례(54.3%), 림파절전이가 8례 (22.9%), 조영증강이 15례 (42.9%), 골증식이 1례 (2.9%)였다. 3. 구강악안면부의 악성종양환자에 있어서, 방사선사진에서 관찰하기 힘들었던, 종양의 구강저, 저작근, 부인두강, 사골동, 측두하와, 악하선, 비강 등 인접조직으로의 침범여부 및 골파괴 정도와 림파절전이를 평가하는 데 자기공명영상은 도움을 주었다. 4. 정진율은, 방사선사진에서 35례중 16례로 45.7%였고, 자기공명영상에서는 35례중 27례로 77.1%로 자기공명영상의 정진율이 더 높았으나, 일반적인 방사선사진이 자기공명영상보다 더 우세한 경우도 2례 있었다.

• The Journal of Korean Academy of Prosthodontics
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• v.53 no.2
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• pp.120-127
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• 2015

Purpose: The aim was to investigate the effect of implant thread designs on the stress dissipation of the implant. Materials and methods: The threads evaluated in this study included the V-shaped, buttress, reverse buttress, and square-shaped threads, which were of the same size (depth). Building four different implant/bone complexes each consisting of an implant with one of the 4 different threads on its cylindrical body ($4.1mm{\times}10mm$), a force of 100 N was applied onto the top of implant abutment at $30^{\circ}$ with the implant axis. In order to simulate different osseointegration stages at the implant/bone interfaces, a nonlinear contact condition was used to simulate immature osseointegration and a bonding condition for mature osseointegration states. Results: Stress distribution pattern around the implant differed depending on the osseointegration states. Stress levels as well as the differences in the stress between the analysis models (with different threads) were higher in the case of the immature osseointegration state. Both the stress levels and the differences between analysis models became lower at the completely osseointegrated state. Stress dissipation characteristics of the V-shape thread was in the middle of the four threads in both the immature and mature states of osseointegration. These results indicated that implant thread design may have biomechanical impact on the implant bed bone until the osseointegration process has been finished. Conclusion: The stress dissipation characteristics of V-shape thread was in the middle of the four threads in both the immature and mature states of osseointegration.

• The korean journal of orthodontics
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• v.38 no.6
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• pp.416-426
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• 2008

The purpose of this study was to evaluate the mobility and ratio of the bone-implant contact (BIC) of a sandblasted, large grit and acid-etched (SLA) orthodontic micro-implant. Methods: Ninety-six micro-implants (48 SLA and 48 machined) were implanted in the upper and lower buccal alveolar bone, and palatal bone of four beagle dogs. Two weeks after surgery, orthodontic force (150-200 g) was applied. Two beagles were sacrificed at 4-weeks and the other two at 12-weeks. Histomorphometric comparisons were made between the SLA experimental group and the machined micro-implant as a control group to determine the ratio of contact between the bone and implant. Micro-implant mobility was also evaluated using $Periotest^{(R)}$. Results: Periotest values showed no statistically significant difference in the upper alveolar and palatal bone between groups except for the lower buccal area. BIC in the upper buccal area showed no significant difference between groups both at 4-weeks and 12-weeks. However, both the groups showed a significant difference in BIC ratio in the rest of the experimental areas between 4 weeks and 12 weeks. The experimental group showed active bone remodeling around the bone-implant interface compared to the control group. Conclusions: There were significant differences in the BIC and the Periotest values between the surface-treated and machined micro-implants according to bone quality in the early stage.

• The korean journal of orthodontics
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• v.27 no.3 s.62
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• pp.391-399
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• 1997

Rapid palatal expansion(RPE) is a method of inducing the new bone formation in the palate by separation of the midpalatal suture, which can be done conveniently by placing heavy force across the maxillary dental arch. This experiment was undertaken to examine the histologic changes after RPE and during retention period. Four young adult dogs(a control dog, three experimental dogs) aged 4 to 6 months old were used for this experiment. Expansion screw($Hyrax^{\circledR}$, Dentarum Inc.) was delevered to the palate and fumed 180 degrees every morning and evening for 8 days, giving a total expansion of 7.2mm. A control dog was sacrified at the starting point of this study without any treatment and three experimental dogs were sacrified after RPE, 14-day retention, and 28-day retention in each. Thereafter, those samples were observed with hematoxylin-eosin(H-E) stain, ground section(Villanueva stain), alkaline phosphatase(ALP) stain, tartrate-resistant acid phosphatase(TRA) stain. The results were as followings: 1. After RPE, collagen fiber bundles were stretched along the midpalatal suture and few osteoblasts were flattened-inactive state and also, a little osteoid tissues was observed. Few multinucleated osteoclasts which had TRAP-positive activity in their cytoplasm were seen in horizontal section, whereas a few osteoclasts were seen in frontal section, especially in the nasal floor side of palatal bone. 2. After 14-day retention, collagen fiber bundles were stretched along the midpalatal suture and few osteoblasts which had ALP-positive activity in their cytoplasm were seen. Few multinucleated osteoclasts which had TRAP-positive activity in their cytoplasm were seen in horizontal section, whereas a few osteoclasts were seen in frontal section, especially in the nasal floor side of palatal bone. 3. After 28-day retention, collagen fiber bundles were arranged like those of control dog and osteoblasts which showed a lot of immature bone formation were cuboidal shape and exhibited ALP-positive activity in their cytoplasm. Few multinucleated osteoclasts which had TRAP-positive activity in their cytoplasm were seen in horizontal section, whereas a few osteoclasts were seen in frontal section, especially in the nasal floor side of palatal bone. According to the above results, the new bone formation after rapid palatal expansion was examined after 14-day retention and significantly increased after 28-day retention.

• Maxillofacial Plastic and Reconstructive Surgery
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• v.11 no.1
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• pp.297-308
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• 1989

These are two case reports of recurrent ossifying and cemento-ossifying fibroma in a year or 5 months following conservative treatment. Ossifying fibroma or cemento-ossifying is a relatively uncommon benign fibro-osseous tumor of the jaws, and is generally believed to originate from periodontal ligaments. In recent, it is not demanded more differentiation of ossifying, cementifying and cemento-ossifying fibroma due to the thought that these lesions represent a spectrum of the same disease process rather than separate entities. The tumor commonly presents as an asymptomatic mass lesion and is usually well-circumscribed clinically so that conservative surgical excision has been the treatment of choice, but on occasion extended surgical procedures may become necessary, especially for those tumors which demonstrate rapid expansions and are poorly encapsulated (either initially or when recurrent) and when tumor growth is progressed aggressively or recurrent. En-bloc resection of mandible with iliac bone and inferior alveolar nerve graft was performed in case 1, recurrent cemento-ossifying fibroma of 32-year old male patient, and extended surgical enucleation of mass including normal marginal bone was done in case 2, recurrent ossifying fibroma of 72-year old female patient. By follow-up check of the patients, we obtained good result without any sings of recurrence.

• The Korean Journal of Nuclear Medicine
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• v.33 no.6
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• pp.512-518
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• 1999

Purpose: We evaluated the usefulness of 24 hour/3 hour radio-uptake ratio, lesion to non-lesion ratio, in differentiating bony metastases from acute (<2 months) and healing (${\geq}2$ months) fractures. Materials and Methods: Sixty-three patients (age range: 26-81, 32 males, 31 females) having 90 lesions (30 bone metastases, 30 acute fractures, 30 healing fractures) were included. Bone scans were obtained 3 and 24 hours after administration of 740 MBq of $^{99m}Tc$-MDP. The ratio of radio-uptake in the lesion to normal area was measured as 24/3 hour radio-uptake ratio ([lesion/non-lesion RUR at 24 hour]/[lesion/non-lesion RUR at 3 hour], 24/3 RUR) and analyzed clinical significance in differentiating bone metastases from acute or healing fractures. Results: Mean 24/3 RUR were $1.22{\pm}0.18$ for bone metastases, $1.25{\pm}0.14$ for acute fractures, and $0.99{\pm}0.15$ for healing fractures. 24/3 RUR values of bone metastases and acute fractures were not significantly different. But 24/3 RUR values of bone metastases and healing fractures, and those of acute and healing fractures were found to be significantly different (p<0.001). When 24/3 RUR of 1.0 was considered as the cut off point separating metastases from fracture, a sensitivity of 100% (30/30) was obtained. The specificity was 0% (0/30) in separating metastases from acute fractures, and 47% (14/30) in separating metastases from healing fractures. When 24/3 RUR of 1.2 was considered as the cut off point, sensitivity of 53% (16/30) in the diagnosis of bone metastasis, and specificity of 37% (11/30) in separating metastases from acute fractures, and 100% (30/30) in separating metastases from healing fractures were obtained. Conclusion: 24/3 RUR is useful in differentiating bone metastases from healing fractures, but not in differentiating bone metastases from acute fractures. A 24/3 RUR of less than 1.0 suggests healing fractures. A 24/3 RUR of more than 1.2 suggests bone metastases or acute fractures.

• Journal of the Korean Orthopaedic Association
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• v.55 no.4
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• pp.338-342
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• 2020

Periosteal chondroma is a rare, slow-growing, benign cartilaginous tumor that develops between the periosteum and cortex, but there are no reports of multiple periosteal chondroma of the toes. A 19-year-old male presented with a palpable mass of the right fourth toe with tenderness for one year. A radiology examination revealed multiple, radio-lucent lesions with mild cortical irregularity. The magnetic resonance imaging findings were chondrogenic tumors with multiple, well-defined T1-low and T2-high signal enhanced lesions involved in the fourth proximal, middle, and distal phalanges. The tumors were removed by a surgical resection and curettage. Histologically, the tumors were proven to be periosteal chondroma.

• Investigative Magnetic Resonance Imaging
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• v.11 no.2
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• pp.127-132
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• 2007

Sinonasal neuroendocrine carcinoma is a rare disease, and reports focusing on the MR imaging findings of sinonasal neuroendocrine carcinoma are extremely rare. Threrefore we intend to report 2 cases of histologically confirmed neuroendocrine carcinoma. A 62-year-old man and a 74-year-old man are both presented with nasal bleeding. Computed tomography(CT) images of the 2 patients showed large, ill-defined masses in sinonasal cavities with adjacent bony destructions. MR images showed masses with isosignal intensity on Tl-weighted images and mixed iso- and high signal intensity on T2-weighted images. Post-contrast MR images showed heterogenous enhancement of masses with necrosis. Adjacent bony destructions were also noted on MR images. In both cases, peritumoral cystic lesions or mucoceles with high signal intensity on T1-weighted images were noted in sphenoid sinus. Both of the CT and MR imaging findings of the 2 patients were nonspecific which are usually seen in malignant tumor. But further study is needed for the significance of the peritumoral cystic areas adjacent the tumors.

• The Journal of Korean Academy of Prosthodontics
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• v.48 no.3
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• pp.215-223
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• 2010

Purpose: The present study was aimed to evaluate the level of cortical bone strain during the placement of an implant. The primary concern was to investigate if the extent of overloading area near the marginal bone could be affected by microthread fabricated at the cervical 1/3 of an implant. Materials and methods: Three dimensional finite element analysis was used to simulate the insertion of 3 implants. Control model was $4.1{\times}10$ mm implant (Submerged model, Dentis Co,, Daegu, Korea) equipped with a main thread only. Type I was with main thread and microthread, and Type II had similar thread pattern but was of tapered body. A PC-based finite element software (DEFORM 3D ver 5, SFTC, Columbus, OH, USA) was used to calculate a total of 3,600 steps of analysis, which simulated the whole insertion. Results: Results showed that the strain field in the marginal bone within 1 mm of the implant wall was higher than 4,000 micro-strain in the control model. The size of bone overloading was 1-1.5 mm in Type I, and greater than 2 mm in Type II implants. Conclusion: These results indicate that the marginal bone may be at the risk of resorption on receiving the implant for all 3 implant models studied. Yet, the risk was greater for Type I and Type II implants, which had microthread at the cervical 1/3.

• Journal of Dental Rehabilitation and Applied Science
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• v.25 no.1
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• pp.61-71
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• 2009

Anchorage control is important in orthodontic treatment. Recently miniscrew is widly used as maximum anchorage in orthodontic treatment, and then it is important to install miniscrew safely without damaging adjacent anatomic structure. In a view of Miniscrew's stability, maxilla is unfavorable than mandible, and moreover maxillary soft buccal bone has disadvantage on stability. so palatal area comes into notice for installation area. We measured distance between palatal roots and bone thickness at midpalatal area using 3D computed tomography, and have found following results. 1. On the comparison of distance between palatal roots, the distance between 2nd premolar and 1st molar was significantly longest and the distance between premolars was significantly shortest. 2. Going toward lateral area from midpalatal suture and posterior area from zero point, bone thickness significantly became shorter and shorter. And 5.0mm palatal sagittal plane has more significance decrease of bone thickness than 2.5mm palatal sagittal plane. According to these results, we can conclude that the palatal installation of miniscrew between 2nd premolar and 1st molar is safest. And it is more safe that comes closer to midpalatal suture and to anterior area in regard to incisive canal.