• Journal of the Korean Association of Oral and Maxillofacial Surgeons
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• 제29권6호
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• pp.379-391
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• 2003

The present study was undertaken to evaluate bone regenerative capacity around titanium screw implants placed in irradiated rat's tibiae. At one week after single 15-Gy dose irradiation, miniaturized titanium screw implants were inserted into anterior aspect of the upper tibia of rats weighing 200-250g. Seventy rats were involved: 35 rats were control and 35 rats radiation group. The rats were killed at different intervals as 1, 2, 3, 4, 6, 8, 12 weeks after implantation for histologic observation, histomorphometric analysis and immunohistochemical study with fibronectin and CD34 antibody. 1. Histologically, various stages of bone maturation and ossification can be seen at 4 weeks and regenerated bone close to edges demonstrates more advanced calcification, and network of new bone are well formed at 12 weeks in non-irradiated group. In contrast, active bone formation with increased contact of newly formed bone to implant surface was noted at 4 weeks and a significant amount of new bone formation and bone-implant contact is oberved at 12 weeks in irradiated group. 2. Histomorphometrical analysis confirmed these histologic findings. A significant difference in implant-bone contact and bone density was measured between the control and radiation group. Mean MBD was 62.2% in control group and 27.5% in radiation group, mean MBIC was 86.6% in control group and 47.7% in radiation group, and mean TBIC was 87.3% in control group and 45.6% in radiation group at 12 weeks after implantation. 3. In immunohistochemical study with fibronectin and CD34, radiation reduced hematopoietic progenitor cells severely and disturbed differentiation of osteoblast in bone marrow. The results of this study revealed bone healing capacity around implant after radiation therapy was severely impaired and irradiation reduces the capacity for osseointegration of titanium implants. Many factors including radiation dose, period between radiation and implantation, bone quality, time elapse between first and second surgery, type of prosthetics and hyperbaric oxygen therapy must be considered carefully in postradiation implantation.

• 대한치과기공학회지
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• 제6권1호
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• pp.31-86
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• 1984

The educational purpose of a junior college is believed to be to effectively train and produce professional workers equipped with the knowledge and skills required in various technical fields of modern society. Since dental technology takes its share of an important role through the enhancement of people's health and the construction of a whlfare society, the prosthodontia department is imposed with a great responsibility to train highly skilled, responsible dental technicians who will meet the social demands. To attain this goal, those who are in charge of the training and education should place emphasis on the development of better educational programs. In other words, the present curriculum which is lacking in many comprehensive aspects, is not satisfactory to provide the students with the required know-how and qualities. As is known, a currculum is the detailed guidance to the efficient operation of an educational program, and that of dental technology is not an exception. In addition, dental technology requires very detailed programs in training, because it requires both diversified and comprehensive application of serveral different fields. The following are the main points to be taken into consideration in developing an effective curriculum for this department. 1. The curriculum should be gradually expanded so that the fundamental subjects will contain principal theories which can be directly applied to the specified majoring subjects. 2. An effective arrangement of time tables should be provided so that basic practice and experiments can be conducted in direct connection with the leatures on the basic theories. 3. For a creative and up-to-date curriculum to help cope with the problems in achieving the aims of technological development and scientific education, intensive and extensive studies should be done on the curricula developed in the advanced countries. 4. The specific majoring subjects should be rearranged to contain new theories which are beneficial to dental technology. As an institution which is spearheaded for ondustrial-educational cooperation, the Junior collegeis role demands that the department should make every possible effect to cultivate highly-skilled technicisns. The following suggestions are made to help work out an ideal curriculum. 1. The basic theory subjects should be selected with consideration toward closely related majoring subjects. 2. The curriculum should be efficiently operated to effectively relate theories with experiments. 3. Subject importance must be rearranged ; It has been found that the ideal proportion of cultural, elective and required subjects is 20%, 20% and 60% respectively. 4. The credit allotments should be reconsidered: The total credits required for completion should preferably be 80; 16 for the cultural and the elective subjects respectively and 48 for the required subject. 5. A Commissioned education system should be formalized for strengthening industrial educational cooperation. 6. Experiments and practice should be intensified with the support of improved laboratory facilities. 7. The training period should be expanded form the present two years to three of four years, in order to produce more highly qualified technicians.

• 대한치과교정학회지
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• 제26권2호
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• pp.125-139
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• 1996

저자는 성장기 III급 부정교합자의 치료후 성장완료시까지 장기관찰 기록을 통하여 III급 부정교합치료 전략 수립에 도움이 되는 유용한 정보를 얻었다. 장기 관찰 결과는 다음과 같이 요약할 수 있었다. 첫째, 전치부 반대교합의 조기 개선시에 상악에서 상당한 전방성장이 많은 증례에서 관찰되었다. 둘째, 악골에 대한 정형적 치료에 의한 성장조절은 장기적인 관점에서 제한적인 효과만 인정되었다. 셋째, 반대교합을 가진 어린 환자에서 얻은 어떤 자료도 장기적인 관점에서 그 환자의 치료후 안정성을 예측할 수 있는 것은 없었다. 그러나 gonial angle은 어느 정도 예측의 가능성을 보였다. 넷째, 성장이 된 연령에서 하악에 대한 정형적 후방력이나 하악의 급작스런 위치 변화는 악관절에 좋지 못한 영향을 줄 수 있었다. 따라서 저자는 다음과 같이 III급 치료 전략을 제시한다. ${\cdot}$반대교합은 가능하다면 조기에 개선하는 것이 좋으며, 정형적 치료는 10세 이전에 1-2년 정도 사용하는 것이 좋겠다. ${\cdot}$ 이후에 바로 phase II 치료에 들어가지 말고 성장이 어느 정도 끝나는 시점까지 기다린다. 즉 여자는 14세, 남자는 17세 경까지 기다린 후에 교정치료로 마무리할 것인지 악교정 수술을 할 것인지 결정한다. 관찰 기간 동안에 성장에 영향을 줄 수 있는 기도문제, 혀자세, 습관, 제3대구치의 발육 등을 감독하고, 성장에 관한 자료를 채득한다. 이렇게 하므로서 앞에서 관찰한 치료 완료 후의 재발로 인한 재치료 문제를 줄일 수 있고,실제적인 치료기간을 단축할 수 있어 환자나 술자에게 모두 유익하다고 생각한다.

• The Journal of Advanced Prosthodontics
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• 제12권2호
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• pp.100-106
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• 2020

PURPOSE. The purpose of this in vitro study was to evaluate the fitting accuracy of single crowns made from a novel presintered Co-Cr alloy prepared with a computer-aided design and computer-aided manufacturing (CAD/CAM) technique, as compared with crowns manufactured by other digital and the conventional casting technique. Additionally, the influence of oxide layer on the fitting accuracy of specimens was tested. MATERIALS AND METHODS. A total of 40 test specimens made from Co-Cr alloy were investigated according to the fitting accuracy using a replica technique. Four different methods processing different materials were used for the manufacture of the crown copings (milling of presintered (Ceramill Sintron-group_cer_sin) or rigid alloy (Tizian NEM-group_ti_nem), selective laser melting (Ceramill NPL-group_cer_npl), and casting (Girobond NB-group_gir_nb)). The specimens were adapted to a resin model and the outer surfaces were airborne-particle abraded with aluminum oxide. After the veneering process, the fitting accuracy (absolute marginal discrepancy and internal gap) was evaluated by the replica technique in 2 steps, before removing the oxide layer from the intaglio surface of the crowns, and after removing the layer with aluminum oxide airborne-particle abrasion. Statistical analysis was performed by multifactorial analysis of variance (ANOVA) (α=.05). RESULTS. Mean absolute marginal discrepancy ranged between 20 ㎛ (group_cer_npl for specimens of Ceramill NPL) and 43 ㎛ (group_cer_sin for crowns of Ceramill Sintron) with the oxide layer and between 19 ㎛ and 28 ㎛ without the oxide layer. The internal gap varied between 33 ㎛ (group_ti_nem for test samples of Tizian NEM) and 75 ㎛ (group_gir_nb for the base material Girobond NB) with the oxide layer and between 30 ㎛ and 76 ㎛ without the oxide layer. The absolute marginal discrepancy and the internal gap were significantly influenced by the fabrication method used (P<.05). CONCLUSION. Different manufacturing techniques had a significant influence on the fitting accuracy of single crowns made from Co-Cr alloys. However, all tested crowns showed a clinically acceptable absolute marginal discrepancy and internal gap with and without oxide layer and could be recommended under clinical considerations. Especially, the new system Ceramill Sintron showed acceptable values of fitting accuracy so it can be suggested in routine clinical work.

• Maxillofacial Plastic and Reconstructive Surgery
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• 제27권2호
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• pp.103-109
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• 2005

In spite of the ongoing advances, standard therapies for oral cancer still has some limitations in efficacy and in ability to prolong survival rate of advanced disease and result in significant functional defect and severe cosmetic deformity. Currently gene therapy using tumor suppressor gene is considered as a potent candidate for new therapeutic approaches that can improve efficacy and reduce complications. The purpose of this research is to identify the role of adenoviral vector to transfer HCCS-1 tumor suppressor gene in oral cancer cells and to find out whether there is a possibility for it to serve in the field of gene therapy. The human SCC-25 cell line was used for transfection. To determine the efficiency of the adenovirus as a gene delivery vector cell line was transduced with LacZ gene and analysed with X-gal staining. Northern blot was performed to confirm the tranfection with HSCC-1 gene and cell viability was assessed by cell cytotoxicity assay. We had successfully construct the recombinant HSCC-1 adenovirus(Ad5CMV-HCCS-1). DNA extracted from Ad5CMV-HCCS-1 revealed HCCS-1 gene is incorporated. The transduction efficiencies were over than 50% of SCC-25 cells with a MOI of 2 and over 95% with a MOI of 50. Northern blot analysis showed that a single 0.6kb mRNA transcript was expressed in Ad5CMV-HCCS-1 transduced SCC-25 cells. There was no or very low transcription HCCS-1 mRNA in wild and Ad5CMV-LacZ transduced SCC-25 cells. Cells transduced with Ad5CMV-HCCS-1 showed significant growth inhibition. By day 6, Ad5CMV-HCCS-1 treated cell count was decreased to 30% of mock-infected cells, while that of Ad5CMV-LacZ treated cells was 90% of mock-infected cells (p<0.05). Finally, these result suggest that the Ad5CMV-HCCS-1 has potential as a gene therapy tool for oral cancer.

• The Journal of Advanced Prosthodontics
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• 제8권1호
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• pp.1-8
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• 2016

PURPOSE. The purpose of this study was to evaluate the efficacy of two different metal conditioners for non-precious metal alloys for the bonding of porcelain to a cobalt-chromium (Co-Cr) alloy. MATERIALS AND METHODS. Disk-shaped specimens ($2.5{\times}10.0mm$) were cast with Co-Cr alloy and used as adherend materials. The bonding surfaces were polished with a 600-grid silicon carbide paper and airborne-particle abraded using $110{\mu}m$ alumina particles. Bonding specimens were fabricated by applying and firing either of the metal conditioners on the airborne-particle abraded surface, followed by firing porcelain into 5 mm in diameter and 3 mm in height. Specimens without metal conditioner were also fabricated. Shear bond strength for each group (n=8) were measured and compared (${\alpha}=.05$). Sectional view of bonding interface was observed by SEM. EDS analysis was performed to determine the chemical elements of metal conditioners and to determine the failure modes after shear test. RESULTS. There were significant differences among three groups, and two metal conditioner-applied groups showed significantly higher values compared to the non-metal conditioner group. The SEM observation of the sectional view at bonding interface revealed loose contact at porcelain-alloy surface for non-metal conditioner group, however, close contact at both alloy-metal conditioner and metal conditioner-porcelain interfaces for both metal conditioner-applied groups. All the specimens showed mixed failures. EDS analysis showed that one metal conditioner was Si-based material, and another was Ti-based material. Si-based metal conditioner showed higher bond strengths compared to the Ti-based metal conditioner, but exhibited more porous failure surface failure. CONCLUSION. Based on the results of this study, it can be stated that the application of metal conditioner is recommended for the bonding of porcelain to cobalt-chromium alloys.

• 대한치과교정학회지
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• 제29권2호
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• pp.183-195
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• 1999

성장기 환자의 교정치료에서 신체의 성장 발육상태를 파악하는 것은 중요한 의미를 갖는다. 특히 부정교합에 따라 성장 발육시기가 차이를 보인다면 교정치료 시기의 선택에 있어서 이에 대한 고려가 있어야 하므로 부정교합의 양상에 따른 성장 발육상태를 평가하는 것이 필요할 것이다. 이에 본 연구에서는 부정교합 분류에 따라 골성숙도에 차이가 있는지를 조사하기 위해, 8-10세의 여자 I급 부정교합자 38명, II급 부정교합자 36명, III급 부정교합자 33명을 대상으로 약 6개월 간격으로 12-13세까지 누년적으로 촬영한 수완부골 방사선 사진을 이용하여 골성숙도를 평가한 결과 다음과 같은 결론을 얻었다. 1. 부정교합에 따른 골성숙도의 차이는 없었다. 2. 유구골의 구상돌기 (hamular process)는 $9.16{\pm}0.72$세, 두상골(pisiform bone)은 $9.13{\pm}0.71$세, 모지척측 종자골(ulnar sesamoid)은 $10.34{\pm}0.84$세에 관찰되었다. 3. 골단이 골간을 둘러싸는 시기는 셋째 수지의 원심부 지절과 중간 지절에서 각각 $10.96{\pm}0.80$세, $11.27{\pm}0.87$세였으며, 첫째 수지의 근심부 지절에서는 $11.12{\pm}0.86$세, 요골에서는 $11.21{\pm}0.82$세, 다섯째 수지의 중간 지절에서는 $11.62{\pm}0.85$세였다. 4. 두상골의 출현은 유구골 구상돌기의 출현과(r=0.91), 모지척측 종자골의 출현은 구상돌기의 진행성 화골시기와 높은 상관관계를 보였으며(r=0.86), 골단이 골간을 둘러싸는 시기는 여러 부위가 상호간에 높은 상관관계를 나타내었다(r=0.80-0.90). 5. 다섯째 수지의 중간 지절의 형태가 가장 변이가 심하였다($20.6\%$).

• 대한치과기공학회지
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• 제23권2호
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• pp.17-47
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• 2002

The purpose of this study was to examine the 2001 curricula in 17 departments of dental technology across the nation in an attempt to find out the educational realities of the departments by term and school year and serve as a basis for the development of more advanced, efficient dental technology curriculum and common educational objectives. For that purpose, the 2001 curricula of the three-year dental laboratory technology departments were analyzed by school year and term to calculate the amount of required credit, the number of subjects, and the weekly classes for electives and major. The findings of this study could be listed as below: 1. The departments of dental laboratory technology nationwide investigated require students to get 120 to 135 credits in total. Out of the credits, 10 to 25 credits are assigned to the electives, and 106 to 11 8 credits are given to the major. 2. There are 50 to 68 subjects in the departments of dental technology. 5 to 16 subjects are the electives, and 41 to 59 are the major. 3. There are 150 to 196 classes per week, which consist of 10 to 30 ones for the electives and 137 to In for the major. 4. The curricula for the first semester of the first year are as follows: 1) 20 to 24 credits are required. 4 to 11 credits are alloted to the electives, and 9 to 19 credits are assigned to the major. 2) The number of subject is 9 to 13, which are composed of 2 to 7 for the electives and 4 to 9 for the major. 3) The weekly classes are 22 to 29. The classes for the electives range from 4 to 14 per week, and 10 to 20 classes a week are for the major. 5. The curricula for the second semester of the first year are as below: 1) There are 20 to 25 credits. 3 to 12 credits are assigned to the electives, and 12 to 19 credits are for the major. 2) The number of subject is 10 to 14, which consist of 2 to 6 for the electives and 6 to 10 for the major. 3) The weekly classes are 22 to 29. and 3 to 12 classes a week are for the electives, and 15 to 24 classes are for the major. 6. The curricula for the first semester of the second year are as below: 1) The number of credits ranges from 20 to 24. Only six colleges offer 2 credits for the electives and the major account for 18 to 24 ones. 2) There are 8 to 12 subjects. Only six colleges offer one or two electives, and 8 to 12 are the major. 3) The weekly classes are 23 to 33. Only six colleges offer 2 or 3 classes a week for the electives, and 21 to 33 classes are for the major. 7. The curricula for the second semester of the second year are as below: 1) The number of credits ranges from 19 to 24. Only two colleges offer 2 credits for the electives and the major account for 18 to 24 ones. 2) There are 7 to 12 subjects. Only two colleges offer one or two electives, and 8 to 12 are the major. 3) The weekly classes are 24 to 36. Only two colleges offer 2 classes a week for the electives, and 24 to 36 classes are for the major. 8. The curricula for the first semester Of the third year are as below: 1) There are 16 to 24 credits. Just a college assigns 2 credits to the electives, and 16 to 24 credits are given to the major. 2) The number of subject is 5 to 12. Only a college offers one elective for optional course, and 5 to 12 are the major. 3) The weekly classes range from 18 to 39. Just a college offer 2 classes a week for the electives, and 18 to 39 classes are for the major. 9. The curricula for the second semester of the third year are as below: 1) There are 16 to 23 credits. Just a college assigns 2 credits to the electives, and 16 to 23 credits are given to the major. 2) The number of subject is 5 to 12. Only a college offers one elective for optional course, and 5 to 12 are the major. 3) The weekly classes range from 18 to 39. Just a college offer 2 classes a week for the electives, and 18 to 39 classes are for the major.