• International Journal of Oral Biology
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• v.37 no.3
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• pp.85-90
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• 2012

Periodontal disease induces an increased incidence of tooth loss, particularly in cases with an associated loss of alveolar bone and periodontal ligaments. In this study, alveolar bone loss was detected by micro-computed tomography (CT) following exposure to E. coli lipopolysaccharide (LPS) in a streptozotocin (STZ)-induced diabetic mouse model. A 10 mg/ml dosage of E. coli LPS was applied between the first, second and third molars of the mice three times a week for 10 weeks. The loss of periodontal ligaments and alveolar processes was then evaluated by micro-CT using two and three dimensional microstructure morphometric parameters. In the diabetic mice, E. coli LPS induced the destruction of periodontal ligaments and loss of alveolar process spaces. The distances between periodontal ligaments were significantly widened in the STZ-LPS group compared with the untreated STZ group. The 10 mg/ml exposure to E. coli LPS in the STZ mice also resulted in a significant decrease in the alveolar bone volume fraction. The results of our study suggest that alveolar bone loss can be readily detected by volumetric micro-CT analysis as an increase in the distance between periodontal ligaments and in the alveolar process length.

• Journal of radiological science and technology
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• v.43 no.3
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• pp.187-194
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• 2020

Bone mineral density is a examination to measure the amount of bone in patients with metabolic bone disease. It is a low dose, but may cause unnecessary exposure to the gonads and other organs located in the periphery when examining the lumbar and proximal femurs. Therefore, the purpose of this study was to evaluated the exposure dose for each organ exposed during the bone mineral density through simulation, and analyzed the applicability of the subject to radiation shielding devices using 3D printing materials. As a result, the highest dose was shown at 11.47 uSv in the breast during lumbar examination and 8.98 uSv in the testis during proximal femur examination. Also, the farther away from the examination site, the lower the effect of the scattering-ray. The shielding effect of using 3D printing shielding device showed high results in proportion to the effective atomic number and specific gravity of the printing material. Among the printing materials, ABS + W showed an effect of at least 78.72 to 96.3 9% compared to the existing lead material.

• Journal of Periodontal and Implant Science
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• v.35 no.3
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• pp.687-702
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• 2005

The purpose of this study is to examine the effect of non-resorbable membrane such as e-PTFE which was used with DFDB in bone regeneration on dehiscence defect in peri-implant area. Amomg the patients, who have recieved an implant surgery at the department of Periodontics in Dan Kook University Dental Hospital, 12 patients showed implant exposure due to the dehiscence defect and 15 implants of these 22 patients were the target of the treatment. Periodontists randomly applied $Gore-Tex^{(R)}$ to the patients and treated them with antibiotics for five days both preoperatively and postoperatively. Reentry period was 26 weeks on average in maxilla and 14 weeks on average in mandible. The results were as follows : 1. Dehiscence bone defect frequently appeared in premolar in mandible and anterior teeth in maxilla respectively. 2. Among 15 cases, 1 membrane exposure was observed and in this case, regenerated area was decreased. 3. In non-resorbable membrane, bone surface area $9.25{\pm}4.84$ preoperatively and significantly increased to $11.48{\pm}7.52$ postoperatively(0.05). 4. The increase of bone surface area in non-resorbable membrane was $2.23{\pm}3.38$. 5. As a result of histopathological finding, DFDB surrounded by new bone formation and lamellate bone, resorption of DFDB and bone mineralization was found. Also, fibrosis of connective tissue beneath the membrane was found. This study shows that the surgical method using DFDB and non-resorbable membrane on dehiscence defect in peri-implant area is effective in bone regeneration.

• Journal of Periodontal and Implant Science
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• v.44 no.5
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• pp.222-226
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• 2014

Purpose: This study aimed to assess the interdental bone level in premolar bitewing radiographs while retracting the cheeks. Methods: Seventy-two horizontal bone defects were created on dried mandibles and maxillae. The distance from the bone level to the cement-enamel junction of premolars was detected by a modified digital caliper (considered the gold standard). The reliability of all radiographs was assessed by intraclass correlation coefficient (ICC), and the validity was compared to the gold standard using the analysis of variance test. P-values less than 0.05 were considered statistically significant. Results: This study showed that the reliability of radiographs without a cheek simulator and with 0.16 second exposure time was significantly higher than that of the two other groups (ICC=0.96 compared to 0.93 and 0.88, respectively). The results from the radiographs without a cheek simulator and with 0.16 second exposure time were more similar to the gold standard measures than those of the two other groups, although the difference was not statistically significant. Conclusions: Retracting the buccal soft tissue plays an important role in increasing the accuracy of radiographs in detecting the interdental alveolar bone level and produces more accurate results than increasing the exposure time, although it does not have a significant role in reliability of results.

• Journal of Dental Rehabilitation and Applied Science
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• v.33 no.1
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• pp.19-24
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• 2017

Recently, flexible denture is widely used with some advantages such as esthetics, flexibility and biocompatibility. However, there is an opposite opinion about stability because of the movement of denture by the material's flexibility. As the denture moves to tissue surface during mastication, it irritates the supporting tissue. It can lead to trauma and rapid resorption of residual ridges if this irritation lasts for a long time. In this case, the patient has used flexible denture with insufficient stability, retention and support for several years and thus continuous irritation of the supporting tissue resulted in palate bone exposure. The patient discomfort and palate bone exposure underwent improvements by the new denture with stability and retention. A careful case selection for flexible denture, regular checkup and proper treatment are necessary to prevent the side effects.

• The Korean Journal of Nuclear Medicine Technology
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• v.21 no.1
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• pp.44-49
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• 2017

Purpose Radiation exposure management has been strictly regulated for the radiation workers, but there are only a few studies on potential risk of radiation exposure to non-radiation workers, especially nurses in a general ward. The present study aimed to estimate the exact total exposure of the nurse in a general ward by close contact with the patient undergoing nuclear medicine examinations. Materials and Methods Radiation exposure rate was determined by using thermoluminescent dosimeter (TLD) and optical simulated luminescence (OSL) in 14 nurses in a general ward from October 2015 to June 2016. External radiation rate was measured immediately after injection and examination at skin surface, and 50 cm and 1 m distance from 50 patients (PET/CT 20 pts; Bone scan 20 pts; Myocardial SPECT 10 pts). After measurement, effective half-life, and total radiation exposure expected in nurses were calculated. Then, expected total exposure was compared with total exposures actually measured in nurses by TLD and OSL. Results Mean and maximum amount of radiation exposure of 14 nurses in a general ward were 0.01 and 0.02 mSv, respectively in each measuring period. External radiation rate after injection at skin surface, 0.5 m and 1 m distance from patients was as following; $376.0{\pm}25.2$, $88.1{\pm}8.2$ and $29.0{\pm}5.8{\mu}Sv/hr$, respectively in PET/CT; $206.7{\pm}56.6$, $23.1{\pm}4.4$ and $10.1{\pm}1.4{\mu}Sv/hr$, respectively in bone scan; $22.5{\pm}2.6$, $2.4{\pm}0.7$ and $0.9{\pm}0.2{\mu}Sv/hr$, respectively in myocardial SPECT. After examination, external radiation rate at skin surface, 0.5 m and 1 m distance from patients was decreased as following; $165.3{\pm}22.1$, $38.7{\pm}5.9$ and $12.4{\pm}2.5{\mu}Sv/hr$, respectively in PET/CT; $32.1{\pm}8.7$, $6.2{\pm}1.1$, $2.8{\pm}0.6$, respectively in bone scan; $14.0{\pm}1.2$, $2.1{\pm}0.3$, $0.8{\pm}0.2{\mu}Sv/hr$, respectively in myocardial SPECT. Based upon the results, an effective half-life was calculated, and at 30 minutes after examination the time to reach normal dose limit in 'Nuclear Safety Act' was calculated conservatively without considering a half-life. In oder of distance (at skin surface, 0.5 m and 1 m distance from patients), it was 7.9, 34.1 and 106.8 hr, respectively in PET/CT; 40.4, 199.5 and 451.1 hr, respectively in bone scan, 62.5, 519.3 and 1313.6 hr, respectively in myocardial SPECT. Conclusion Radiation exposure rate may differ slightly depending on the work process and the environment in a general ward. Exposure rate was measured at step in the general examination procedure and it made our results more reliable. Our results clearly showed that total amount of radiation exposure caused by residual radioactive isotope in the patient body was neglectable, even comparing with the natural radiation exposure. In conclusion, nurses in a general ward were much less exposed than the normal dose limit, and the effects of exposure by contacting patients undergoing nuclear medicine examination was ignorable.

• Archives of Plastic Surgery
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• v.34 no.5
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• pp.667-670
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• 2007

Purpose: Among the materials for cranioplasty, autogenous bone is ideal because it is less susceptible to infection and has lower rates of subsequent exposure. However, the procedure is technically demanding to perform and requires a donor site. Disadvantages further exist when the defect is large and there are attendant limitations in donor site. The authors present their experience with reconstruction of large skull defect using right-angled zigzag osteotomized outer table of autogenous calvarial bone, overcoming the limitation in donor site. Methods: From 2000 to 2006, 9 patients were retrospectively reviewed, who had undergone reconstruction with right angled zigzag osteotomized outer table of autogenous calvarial bone. Results: Aesthetically satisfactory skull shape was achieved. Major complications of infection, hematoma, plate exposure, and donor site complications of dural tear with bleeding, cerebrospinal fluid leak, and meningitis were not seen. One patient had delayed wound healing and was successfully managed conservatively. Conclusion: Autogenous bone is the material of choice for cranioplasty, especially in complicated cases. Right angled zigzag osteotomy is a useful method in reconstruction of large skull defects with less donor site morbidity.

• Imaging Science in Dentistry
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• v.30 no.2
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• pp.101-108
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• 2000

Purpose : The effects of step numbers of copper wedge and exposure on the coefficient of determination (r²) of the conversion equation to Cu-equivalent image and on the Cu-equivalent value (mmCu) and it's coefficient of variation measured at each copper step and the mandibular premolar area were evaluated. Method: Digital image analyzing system consisted of scanner, personal computer, and a stepwedge with 10 steps of 0.03 mm copper in thickness as reference material was prepared for quantitative assessment of the bone mineral density. NIH image program was used for analyzing images. Results : The film having moderately high film density showed the discrepancy between the real thickness and the measured Cu-equivalent value of each copper step. The Cu-equivalent image was dependent on the determinational coefficient of the conversion equation than the coefficient of variance of the measured value. Conclusion : Obtaining conversion equation with high coefficient of determination and proper film exposure are supposed to be neccessary for quantitative assessment of bone density. Multiple steps in the range of the corresponding copper thickness to the bone density of the area to be measured should be prepared.

• Journal of the Korean Association of Oral and Maxillofacial Surgeons
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• v.28 no.4
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• pp.280-285
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• 2002

As the result of the study concerning "bone inducibility of chitosan", 1. "BMP-2" was observed mainly through the test when the "osteoblast" is exposed to the "chitosan". The expression of BMP-2 was 542.63 times compared to control after 2 hours exposure and it was maintained 16.60 times till 24 hours. 2. The expression of BMP-4 was decreased compared to control during exposure. 3. The expression of BMP-7 revealed two peaks during exposure. 4. The expression of osteocalcin was increased in early phase, and then decreased. Although it is not clear whether the "chitosan" is clinically effective material as a "bone induction material", we could say that it has a function for bone induction. Further detailed study will be required.

• Journal of Periodontal and Implant Science
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• v.38 no.2
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• pp.253-262
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• 2008

Background: Incomplete flap coverage or early exposure over implants and/or barrier membranes have a negative effect on bone regeneration. In cases of using regenerative techniques, complete soft tissue coverage of the implant area is necessary to promote adequate conditions for guided bone regeneration. Primary socket closure may be difficult, when periosteal releasing incision is only used, due to the opening left by extracted tooth. Therefore, Soft tissue grafting techniques are used to achieve primary soft tissue closure. Materials and Methods: Soft tissue grafting techniques, with or without barrier membranes, were performed for primary closure in four cases of immediate placements. Three different methods were used (CTG, VIP-CT, Palatal advanced flap). Clinical results of the grafting were evaluated. Result: One case showed early exposure of cover-screw and, no other complications were noted. In the others, Primary closure was achieved by soft tissue grafting techniques. One of the cases, Graft showed partial necrosis, but there were no exposure over implants and/or barrier membranes. Conclusion: The use of grafting techniques, in immediate implant placement, can predictably obtain primary closure of extraction sockets, thereby providing predictable bone formation and improved implant results.