• 구강회복응용과학지
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• 제17권3호
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• pp.199-204
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• 2001

This study was to investigate the reused possibility of zirconia reinforced glass-ceramic(IPS Empress Cosmo ceramic) with sprue button in the flexure strength and fracture toughness. 40 disk-shaped ceramic specimens (20 specimens: as-pressed material; 20 specimens: reused material) with approximately 1.7 mm thickness and 15 mm diameter were prepared by "lost wax" technique. The remnants(sprue buttons) were used for repressing. The surface treatments for the discs were gradually abraded with 320, 800, 1200, and 2000 grit SiC sandpaper. The specimens were evaluated their flexure strength with the biaxial flexure jig(ball-on-three balls) and their fracture toughness with Vickers Indentation-microfracture test. The Weibull moduli were calculated for biaxial flexural strength. The mean flexure strength and fracture toughness of each group were $122.2{\pm}18.3MPa$, $1.00{\pm}0.09MPa{\cdot}m^{0.5}$ (as-pressed ceramics), and $122.2{\pm}20.3MPa$, $1.01{\pm}0.10MPa{\cdot}m^{0.5}$ (reused ceramics). There were no significant differences in the strength and the fracture toughness between the as-pressed and the reused IPS Empress Cosmo ceramic (P>0.05). This implied zirconia reinforced glass-ceramic(IPS Empress Cosmo ceramic) could be used one more time by reusing of sprue button in the flexure strength and fracture toughness.

• Journal of the Korean Association of Oral and Maxillofacial Surgeons
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• 제42권2호
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• pp.84-89
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• 2016

Objectives: To compare the efficacy of intravenous ondansetron (4 mg, 2 mL) and granisetron (2 mg, 2 mL) for preventing postoperative nausea and vomiting (PONV) in patients during oral and maxillofacial surgical procedures under general anesthesia. Materials and Methods: A prospective, randomized, and double blind clinical study was carried out with 60 patients undergoing oral and maxillofacial surgical procedures under general anesthesia. Patients were divided into two groups of 30 individuals each. Approximately two minutes before induction of general anesthesia, each patient received either 4 mg (2 mL) ondansetron or 2 mg (2 mL) granisetron intravenously in a double blind manner. Balanced anesthetic technique was used for all patients. Patients were assessed for episodes of nausea, retching, vomiting, and the need for rescue antiemetic at intervals of 0-2, 3, 6, 12, and 24 hours after surgery. Incidence of complete response and adverse effects were assessed at 24 hours postoperatively. Data was tabulated and subjected to statistical analysis using the chi-square test, unpaired t-test, or the Mann-Whitney U-test as appropriate. A P-value less than 0.05 was considered statistically significant. Results: There was no statistically significant difference between the two groups for incidence of PONV or the need for rescue antiemetic. Both study drugs were well tolerated with minimum adverse effects; the most common adverse effect was headache. The overall incidence of complete response in the granisetron group (86.7%) was significantly higher than the ondansetron group (60.0%). Conclusion: Granisetron at an intravenous dose of 2 mg was found to be safe, well tolerated, and more effective by increasing the incidence of complete response compared to 4 mg intravenous ondansetron when used for antiemetic prophylaxis in maxillofacial surgery patients receiving general anesthesia. Benefits of granisetron include high receptor specificity and high potency, which make it a valuable alternative to ondansetron.

• 대한치과보철학회지
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• 제54권3호
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• pp.253-258
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• 2016

최근 CAD-CAM과 지르코니아를 이용한 보철물의 제작이 증가하고 있으며 구강스캐너의 발달로 임상 및 기공과정이 단순화되고 있다. 균열치 혹은 치아의 일부가 파절된 경우, 구강스캐너를 사용하여 치아 삭제 전에 치아의 형태를 미리 스캔하고, 추후 수복물 제작 시 중첩을 통해 단일체 지르코니아 전장관을 제작하면 원래 환자의 자연치 형태와 교합을 재현할 수 있다. 본 증례에서는 균열 및 파절된 치아에서 구강 스캐너, CAD-CAM 및 단일체 지르코니아 전장관을 사용하여 삭제 전 치아의 형태와 교합을 재현한 수복물을 제작하였으며, 교합조정을 최소화할 수 있었다. 또한 임상적으로 기능적이고 심미적인 결과를 얻을 수 있었다.

• 대한치과교정학회지
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• 제35권3호
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• pp.238-249
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• 2005

악골부조화가 심할수록 기능향상을 위해 악골 및 치아 치조부에서의 보상반응이 현저해진다. 대표적인 현상으로 하악과두의 변위와 상악교합평면의 변화 등을 들 수 있다. 이러한 상하악골에서의 적응성 변화는 안모의 심미성과 교합의 기능 향상을 위해, 술후 안정성을 높이기 위해서 악교정수술을 통해 반드시 수정해야 할 요소이다 적절한 상악골 수술을 위해서 통상적으로 model surgery를 시행하여 왔으나 이의 단점을 보완하기 위해 Surgical Jaw Relator를 고안하였으며 이는 교합기의 mounting plate 대신에 부착함으로써 상하악 모형의 삼차원적 이동과 회전이 가능하도록 설계되어 있으며 기존의 모든 종류(Panadent. Sam, Denar, Hanau 등)의 교합기에 손쉽게 부착하여 수술용 스프린트의 제작 시간을 대폭 줄일 수 있는 장점이 있다 상악골 상방 이동이 필요한 하악전돌 증례와 상악골 하방 이동이 요구되는 하악후퇴 증례 등에 본 기구를 적용한 결과 양호한 수술 결과를 얻었으며, 이로써 정교한 상악 수술을 요하거나 명확한 수술 계획이 설정된 증례 등에서 본 기구를 적절하게 사용할 경우 수술용 스프린트를 효율적으로 제작하는데 다소 도움이 될 것으로 생각된다.

• Imaging Science in Dentistry
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• 제33권3호
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• pp.137-141
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• 2003

Purpose: To evaluate the precision of measurements taken of dental implants in bucco-lingually sectioned views of the maxilla by linear tomograms of the panorama and to assess the visibility of the inferior wall of the maxillary sinus. Materials and Methods : Eighty sites prepared with implants of gutta percha cone in the sockets of the upper premolars and molars of 10 dry skulls were radiographically examined using linear tomograms of panorama, and scanned coronally and axially by computed tomography. The differences in mm between the measurements in bucco-lingually sectioned images of maxillary alveolar bone and the true length and width of the implanted gutta percha cones were compared as mean values (mean) and standard deviations (SD) for each radiographic technique. Linear tomography of panorama was compared with computed tomography for visualization of the relationship between the inferior wall of maxillary sinus and the end of each implant. Results: The deviations between the actual implant length and the measured values taken from the linear tomograms (0.44±0.39 mm) was significantly less than the measured values from the multiplanar reconstructed images of the axially scanned computed tomogram (1.21 ± 0.90 mm). There was statistically significant difference (p < 0.05) between two techniques in the differences between the measurements and true implant length. The relationship of the inferior border of maxillary sinus with end of implant was worse identified with the linear tomogram of panorama (68%) than the multiplanar reconstructed image of axially scanned computed tomogram (99%). Conclusion: We could not find any differences in the accuracy of length measurement between the linear tomogram of panorama and computed tomogram, but computed tomogram allowed for a better visualization of the inferior wall of the maxillary sinus than the linear tomogram.

• The Journal of Advanced Prosthodontics
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• 제7권3호
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• pp.199-206
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• 2015

PURPOSE. The present study investigated the influences of various gypsum materials on the precision of fit of CAD/CAM-fabricated prostheses and analyzed their correlation with surface roughness. MATERIALS AND METHODS. The master model of the mandibular right first molar was replicated, and four experimental groups based on two types of Type IV stone (GC Fujirock EP, Die keen) and two types of scannable stone (Aesthetic-Basegold, Everest Rock) were created to include a total of 40 specimens, 10 in each group. The surface roughness of the working models for the respective experimental groups was measured. Once the zirconia cores had been fabricated, the marginal and internal fits were measured with a digital microscope using the silicone replica technique. The mean and standard deviation of the respective points of measurement were computed and analyzed through the one-way ANOVA and Tukey's HSD test. The correlation between surface roughness and the precision of fit of the zirconia core was analyzed using the Pearson correlation analysis (${\alpha}$=.05). RESULTS. The zirconia cores fabricated from the scannable stone working models exhibited a superior precision of fit as compared to those fabricated from the Type IV stone working models. The correlation analysis results showed a clear positive correlation between surface roughness and the precision of fit of zirconia cores in all of the experimental groups (P<.05). CONCLUSION. The results confirmed that the surface roughness of dental working models has a decisive influence on the precision of fit of zirconia cores.

• Journal of Periodontal and Implant Science
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• 제46권2호
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• pp.96-106
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• 2016

Purpose: Stress distribution and mandible distortion during lateral movements are known to be closely linked to bruxism, dental implant placement, and temporomandibular joint disorder. The present study was performed to determine stress distribution and distortion patterns of the mandible during lateral movements in Class I, II, and III relationships. Methods: Five Korean volunteers (one normal, two Class II, and two Class III occlusion cases) were selected. Finite element (FE) modeling was performed using information from cone-beam computed tomographic (CBCT) scans of the subjects' skulls, scanned images of dental casts, and incisor movement captured by an optical motion-capture system. Results: In the Class I and II cases, maximum stress load occurred at the condyle of the balancing side, but, in the Class III cases, the maximum stress was loaded on the condyle of the working side. Maximum distortion was observed on the menton at the midline in every case, regardless of loading force. The distortion was greatest in Class III cases and smallest in Class II cases. Conclusions: The stress distribution along and accompanying distortion of a mandible seems to be affected by the anteroposterior position of the mandible. Additionally, 3-D modeling of the craniofacial skeleton using CBCT and an optical laser scanner and reproduction of mandibular movement by way of the optical motion-capture technique used in this study are reliable techniques for investigating the masticatory system.

• 대한치과기공학회지
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• 제13권1호
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• pp.53-59
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• 1991

This study aimed at inquiring into the basic theory on CIEO(the Cooperation between Industry and Educational Organizations), grasping and analyzing the present situation of the health junior college, the present condition of CIEO and into problem and seeking to find a solution to activate the CIEO of the health junior colleges. This study suggested five methods as the method of consolidating the on-the-spot-training as below : 1. The execution of the basic research for the on-the-spot-training. And the reorganization of the existing curriculum into the curriculum the industrial organization requires. 2. The participation in solving commonly the problems of the industrial organization and in education. The establishing of the guidance system assuming exclusive charge of the on-the-spot-training. 3. The extension of the period of the on-the-spot-training and the reorganization of an educational system. The submission of the evaluation sheet for the on-the-spot-training. 4. The securing of the educational dost spent on the on-the-spot-training and the imposition of benefits on the industrial organization. 5. The persistent support for the on-the-spot-training at the governmental dimension. It is required that the CIEO law should be enacted as the legal and institutional solution and that government should lend systematic support to the business enterprise exeuting the industrial educational cooperation such as the institutional support for and the imposition of benifits on the cost of research. The cost of research and development, the cost of internal education and training, and the cost of experiment and practice.

• 대한치과의사협회지
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• 제49권4호
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• pp.211-218
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• 2011

Purpose: An impacted tooth is defined as a tooth that shows delayed eruption and is expected to erupt incompletely by clinical and radiograph examination despite it reaching its expected time of eruption. The aims of this study were to investigate the clinical and radiological characteristics and treatment duration and method of impacted teeth in Korean patients. Materials and Methods: For this study we used clinical records, study models, panoramic radiographs and intraoral photographs of patients who attended Gachon University Gil Hospital Orthodontic Department between 2005 and 2008. There were 164 patients with a total number of 202 impacted teeth. Results: Male patients shows a little more prevalence than female patients (1.13:1). The under 12 age group had the highest prevalence of tooth impaction, and the over 19 age group showed the least prevalence of tooth impaction. The ratio of tooth impaction between the left to right ratio was 1.73:1 and maxilla and mandible was 1.84:1. The impacted teeth were most commonly positioned buccally (76 cases, 41.5%). Full nap closure technique (108 cases, 81.2%)was most frequently used for attachment of surgical traction hooks. Maxillary canine impaction was most commonly encountered both in male and female patients. The mean treatment period was 12.2 months and the success rate of treatment was 90.3%. The canine tooth shows the longest treatment time and highest failure rate. The ankylosis was the major cause of failure. Conclusion: Impacted teeth most commonly show in left side maxilla in the under 12 age group. And it is most commonly positioned buccally. The mean treatment period was 12.2 months, and the success rate of treatment was 90.3%.

• 대한약리학회지
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• 제31권3호
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• pp.271-278
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• 1995

Barbiturates의 분자적 약리학적 작용기전 연구에 기초자료를 제공키 위하여 본연구를 수행하였다. 분자적 약리작용 기전 연구에서는 무엇보다도 선행되어야 하는 것이 barbiturates가 신경세포막에서 어느 부위에 주로 분포되는가를 알아내는 데에 있다. 쥐(Rat)의 뇌로부터 분리한 synaptosomal plasma membrane vesicles (RSPMV)를 분리한 후 이 RSPMV 외측 단층(outer monolayer)의 소수성 부위와 친수성 부위에 barbiturates가 분포되는 경향을 형광 probe 법으로 검색하였다. 세포막 외측 단층의 친수성 부위에 분포되는 형광 probe N-octadecylnaphthyl-2-amino-6-sulfonic acid (ONS)와 소수성 부위에 분포되는 형광 probe12-(9-anthroyloxy)stearic acid (AS)를 각각 봉입한 후 형광소광법으로 barbiturates의 분포를 측정한 결과는 다음과 같다. 1) 대부분의 barbiturates가 RSPMV 외측 단층의 친수성 부위(표면)에 분포되고 소수성 부위 (hydrophobic region)에 극히 소량만이 분포된다는 것을 확인하였다. 2) 마취효과를 크게 일으키는 barbiturates일수록 소수성 부위에 분포되는 양이 증가하였다. barbiturates 종류에 따른 RSPMV 외측 단층 소수성 부위에의 분포 크기는 thiopental sodium > pentobarbital > hexobarbital > amobarbital > phenobarbital의 순위였다.