• The Journal of Korean Academy of Prosthodontics
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• v.53 no.3
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• pp.189-197
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• 2015

Purpose: The aim of this study was to assess the degree of awareness and actual practice of dental practitioners regarding infection control during prosthodontic treatment. Materials and methods: Study participants were composed of dentists, dental hygienists, dental technicians working at dental university hospital, general hospital, dental hospital and dental clinics in Daejeon, Korea (n=126). The questionnaires included the data on general characteristics, education, awareness and practice of infection control procedures during prosthodontic treatment through personal self-administration survey. Awareness and practice were measured by Likert scale ranging from 1 to 5. Statistical analysis was done by one-way ANOVA. Influence of awareness on practice was estimated by regression analysis. Results: 27.7% of the respondents answered that the infection control education regarding prosthodontic treatment is insufficient. The mean value of awareness and practice of infection control during the prosthodontic treatment were $2.72{\pm}0.80$, $1.58{\pm}0.88$, respectively. The mean value of practice who answered that had education curriculum at college was $1.62{\pm}0.9$, and $1.31{\pm}0.49$ who did not. The mean value of awareness who equipped guideline was $3.01{\pm}0.9$, and $2.56{\pm}0.70$ who did not. Conclusion: 1. The respondents who received the infection control education by college curriculum showed higher degree of practice than the respondents who did not. 2. The respondents who have appropriate infection control guidebook in their workplace showed higher degree of awareness than the respondents who did not. 3. There was a correlation between the awareness and practice of infection control during prosthodontic treatment; the degree of awareness becomes higher, so does the degree of practice. 4. During the prosthodontic treatment, the degree of practice was lower than the degree of awareness on infection control.

• The Journal of Korean Academy of Prosthodontics
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• v.52 no.2
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• pp.82-89
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• 2014

Purpose: The purpose of this study was to observe the change of viscoelastic properties of dental resin cements during polymerization. Materials and methods: Six commercially available resin cement materials (Clearfil SA luting, Panavia F 2.0, Zirconite, Variolink N, RelyX Unicem clicker, RelyX U200) were investigated in this study. A dynamic oscillation-time sweep test was performed with AR1500 stress controlled rheometer at $32^{\circ}C$. The changes in shear storage modulus (G'), shear loss modulus (G"), loss tangent (tan ${\delta}$) and displacement were measured for twenty minutes and repeated three times for each material. The data were analyzed using one-way ANOVA and Tukey's post hoc test (${\alpha}$=0.05). Results: After mixing, all materials demonstrated an increase in G' with time, reaching the plateau in the end. RelyX U200 demonstrated the highest G' value, while RelyX Unicem (clicker type) and Variolink N demonstrated the lowest G' value at the end of experimental time. Tan ${\delta}$was maintained at some level and reached the zero at the starting point where G' began to increase. The tan ${\delta}$and displacement of the tested materials showed similar pattern in the graph within change of time. The displacement of all 6 materials approached to zero within 6 minutes. Conclusion: Compared to other resin cements used in this study, RelyX U200 maintained plastic property for a longer period of time. When it completed the curing process, RelyX U200 had the highest stiffness. It is convenient for clinicians to cement multiple units of dental prostheses simultaneously.

• The Journal of Korean Academy of Prosthodontics
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• v.51 no.3
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• pp.160-166
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• 2013

Purpose: The purpose of this study was to compare the fracture strength of traditional metal-ceramic crowns and full zirconia crowns according to the occlusal thickness. Materials and methods: A mandibular first molar resin tooth was prepared with 1.5 mm occlusal reduction, 1.0 mm rounded shoulder margin and $6^{\circ}$ taperness in the axial wall. Duplicating the resin tooth, 64 metal dies were fabricated. 48 full zirconia crowns were fabricated using Prettau zirconia blanks by ZIRKONZAHN CAD/CAM and classified into six groups according to the occlusal thickness (0.5 mm, 0.6 mm, 0.7 mm, 0.8 mm, 0.9 mm, 1.0 mm). 16 metal-ceramic crowns were fabricated and classified into two groups according to the occlusal porcelain thickness (1.0 mm, 1.5 mm). All crowns were cemented on each metal die and mounted in a universal testing machine. The load was directed at the functional cusp of each specimen until catastrophic failure occurred. One-way ANOVA, Tukey multiple comparison test (${\alpha}=.05$) and t-test (${\alpha}=.05$) were used. Results: The results were as follows. 1. The test 1 group (646.48 N) showed the lowest fracture strength (P<.05), and the value of the test 2.3.4.5 groups (866.40 N, 978.82 N, 1196.82 N, 1222.41 N) increased as thickness increased, but no significant difference were found with the groups (P>.05). The value of test 6 group (1781.24 N) was significantly higher than those of the other groups (P<.05). 2. There were no significant differences of the fracture strength of metal ceramic crowns according to occlusal porcelain thickness 1.0 mm (2515.71 N) and 1.5 mm (3473.31 N) (P<.05). Conclusion: Full zirconia crown needs to be 1.0 mm or over in occlusal thickness for the posterior area to have higher fracture strength than maximum bite force.

• The Journal of Korean Academy of Prosthodontics
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• v.51 no.3
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• pp.175-182
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• 2013

Purpose: The purpose of this study was to investigate the effect of different administration duration of alendronate on initial wound healing and new bone formation of extraction socket in rats. Materials and methods: Fifteen male Sprague-Dawley rats (body weight 130-140 g, 4 weeks old, male) were divided into control group (no alendronate administration) and experimental group (alendronate administration). Experimental group was subdivided into 1 week administrated group, 2 week administrated group, 4 week administrated group and 6 week administrated group according to duration of administration. For the experimental groups, during the designated time period (at the time of extraction, 1 week before extraction, 3 week before extraction and 5 week before extraction) till 1 week after extraction, rats were subcutaneously injected with Alendronate at the dose of 1.0 mg/Kg three times a week. Each specimen from 6 week experimental group and control group were used for microarray analysis, and other specimens were used for histological analysis. The rate of new bone formation within the extraction site and bone loss activity was analyzed using TRAP staining. Statistical analysis was performed using Kruskal Wallis test. (${\alpha}=.05$) Results: After one week from the time of extraction, the rate of new bone formation within extraction site for the control group ($16.77%{\pm}1.36%$) compared to the 4 week experimental group ($14.99%{\pm}6.26%$) was lower. However, no statistically significant difference was found. Increase in the number of inactive lacuna (empty lacuna) and decrease in the number of TRAP positive cell were identified with increased duration of administration. There was no significant difference. Conclusion: The results of this study showed as the duration of Alendronate administration increased the rate of new bone formation decreased with loss of bone activity and reduced number of osteoclast.

• The Journal of Korean Academy of Prosthodontics
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• v.58 no.2
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• pp.77-85
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• 2020

Purpose: The aim of the present study was to investigate the effects of N-acetyl cysteine (NAC) loading on the bone formation surrounding sandblasted, large-grit and acid-etched (SLA) implants. Materials and methods: Implantation of NAC loaded SLA implants (NSI group) and SLA implants (SI group) was performed bilaterally in the mandible of 4 adult beagle dogs (each group, n = 8). The animals were sacrificed after a healing period of 3 and 6 weeks, respectively (n = 2 animal each). Dissected blocks were processed for histomorphometrical analysis. Bone to implant contact percentage (BIC%) and bone volume (BV%) were assessed histomorphometrically. Results: BIC% of NAC loaded SLA implants were about 50% higher than that of SLA implants at 3 weeks of bone healing, but not significantly (51.79 vs 35.43%; P=.185). BV% of NAC loaded SLA implants were significantly higher than that of SLA implants at 3 weeks of bone healing (45.09 vs 37.57 %; P=.044). At 6 weeks of bone healing, BIC% and BV% of two experimental groups were similar (P>.05). Conclusion: Within the limits of the present study, NAC loading have a positive effects on the early bone formation surrounding SLA implants. So, it might be concluded that NAC loading enhance the osseointegration and shorten the healing time after implantation of the SLA implants.

• Tuberculosis and Respiratory Diseases
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• v.60 no.3
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• pp.314-320
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• 2006

Background : The overall response (20-30%) to chemotherapy in non-small cell lung cancer (NSCLC) is quite poor. Heme oxygenase-1 (HO-1) is the rate-limiting enzyme in heme degradation. There is increasing evidence suggesting that the induction of HO-1 might have an important protective effect against oxidative stress including cisplatin containing chemotherapy. This study retrospectively investigated the relationship between HO-1 expression and the response to chemotherapy containing cisplatinin advanced NSCLC patients. Material and Methods : The medical records including the responses to chemotherapy of fifty nine cases were evaluated retrospectively, and the tissue samples of these patients were immunohistochemically stained for HO-1. Results : Forty three of the fifty nine patients(72.8%) showed positive staining for HO-1 in their cancer tissues. There was no significant difference according to the cell type, stage and tumor size. In addition, there was no correlation between HO-1 expression and the responses to chemotherapy. Conclusion : HO-1 expression in tumor tissue dose not predict the response to cisplatin containing chemotherapy in advanced NSCLC. Further prospective studies with a larger number of patients will be needed to confirm these results.

• Investigative Magnetic Resonance Imaging
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• v.4 no.1
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• pp.34-41
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• 2000

Purpose: To evaluate the clinical usefulness of diffusion weighted MR imaging(DWI) in the differential diagnosis of brain tumors. Materials and methods: DWI and conventional MR images of nineteen patients with brain tumors(10 metastatic tumors, 4 high grade gliomas, 4 low grade astrocytomas, one oligodendroglioma)were obtained on 1.5T unit. DWI was obtained using single shot spin echo planar imaging with b-value near 1000. We analyzed the signal intensities of lesions including solid portion, necrotic or cystic portion and peritumoral edema of brain tumors (classified five grades comparison with the signal intensities of brain parenchyma and CSF)and calculate the SIR(signal intensity ratio)of lesions to the contralateral normal brain parenchyma. We analyzed statistically the signal intensities and SIR of tumors using independence T test. Results: In solid portions of tumors, all the metastatic tumors and high grade gliomas showed high signal intensities, but low grade astrocytomas and oligodendroglioma showed iso or slight high signal intensities to the normal brain parenchyma. The SIR of solid portion has positive correlation with malignant pot ential(metastatic tumors 1.52, high grade gliomas 1.38, low grade astrocytomas 1.16, oligodendroglioma 1.31)(p < 0.05). In peritumoral edema where seen in 14 tumors, seven of 10 metastatic tumors and two of 4 high grade gliomas showed iso signal intensities, whereas edemas in other 5 brain tumors showed hyperintense to the normal brain parenchyma. The SIRs of peritumoral edemas in metastatic tumors (1.14) was lower than high grade gliomas(1.31),but statistically insignificant. The SIR of cystic or necrotic portion of brain tumors was 0.63. In non enhancing solid portions, three of six cases showed hyperintense to the adjacent peritumoral edema. Conclusion: On DWI, the signal intensities of solid portion has positive correlation with malignant potential, and perilesional edema of brain tumors appear various signal intensities owing to "T2 shine through effect" and the extensiveness of vasogenic edema. Another merit using DWI on the evaluation of brain tumors is to improved better delineation of tumor margins from the adjacent edemas, especially at the non enhancing solid portion of the tumors.

• Journal of the Korean Society of Radiology
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• v.8 no.7
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• pp.467-477
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• 2014

The purpose of this study is to offer data base for establishment of dental training x-ray generator based safety usage through surveying real radiation safety management state of radiation worker's in plan of operations that have dental training x-ray generators and use it. For it, comprehensive references were surveyed referring reports of current state of regulation technique development and domestic radiation safety evaluation and nuclear related legislation regarding radiation safety management of dental training x-ray generators. On the basis of it, questionnaires were filled in about respondent's general characteristic radiation safety manager's status current state of radiation safety management and the level of knowledge & consciousness. For the study, the survey was conducted to 224 people of radiation safety managers and university graduates training assistants and full-time professors who can treat dental training x-ray generators in education center. through this survey 95 questionnaires were used as analysis materials except the insufficient and omitted responses. As a method of analysis, the frequency and percentage were figured out with the general characteristics and safety manager's status. Chi-square test for frequency and correlation per question analysis and Pearson correlation analysis for crosslevel correlation were done with current state of radiation safety management and knowledge & consciousness level. As a result, running dental training x-ray generators was dealt with by 20's to 40's who have high education level over post undergraduate degree and major in dental hygienic. In addition, female have higher consciousness level for radiation safety management than male. It shows significal linear relation statistically(${\chi}^2$ >5, 0.1${\chi}^2$ >5, 0.3${\chi}^2$ >5, 0.3

• Journal of the Korean Society of Radiology
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• v.11 no.6
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• pp.493-500
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• 2017

In this study, data analysis has been conducted by INFINITT program to analyze the effect of signal to noise ratio(SNR) and contrast to noise ratio(CNR) of flow related enhancement(FRE) and computed tomography Angiography(CTA) on cerebrovascular diseases for qualitative evaluations. Based on the cerebrovascular image results achieved from 63 patients (January to April, 2017, at C University Hospital), we have selected 19 patients that performed both FRE-MRA and CTA. From the 19 patients, 2 were excluded due to artifacts from movements in the cerebrovascular image results. For the analysis conditions, we have set the 5 part (anterior cerebral artery, right and left Middle cerebral artery, right and left Posterior cerebral artery) as the interest area to evaluate the SNR and CNR, and the results were validated through Independence t Test. As a result, by averaging the SNR, and CNR values, the corresponding FRE-MRA achieved were: anterior cerebral artery ($1500.73{\pm}12.23/970.43{\pm}14.55$), right middle cerebral artery ($1470.16{\pm}11.46/919.44{\pm}13.29$), left middle cerebral artery ($1457.48{\pm}17.11/903.96{\pm}14.53$), right posterior cerebral artery ($1385.83{\pm}16.52/852.11{\pm}14.58$), left posterior cerebral artery ($1318.52{\pm}13.49/756.21{\pm}10.88$). by averaging the SNR, and CNR values, the corresponding CTA achieved were: anterior cerebral artery ($159.95{\pm}12.23/123.36{\pm}11.78$), right middle cerebral artery ($236.66{\pm}17.52/202.37{\pm}15.20$), left middle cerebral artery ($224.85{\pm}13.45/193.14{\pm}11.88$), right posterior cerebral artery ($183.65{\pm}13.47/151.44{\pm}11.48$), left posterior cerebral artery ($177.7{\pm}16.72/144.71{\pm}11.43$) (p < 0.05). In conclusion, MRA had high SNR and CNR value regardless of the cerebral infarction or cerebral hemorrhage observed in the 5 part of the brain. Although FRE-MRA consumed longer time, it proved to have less side effect of contrast media when compared to the CTA.

• Journal of Genetic Medicine
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• v.6 no.1
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• pp.74-80
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• 2009

Purpose: To assess the value of first-trimester pregnancy-associated plasma protein-A (PAPP-A), nuchal translucency (NT) and second-trimester alpha-fetoprotein (AFP), human chorionic gonadotropin (hCG), unconjugated estriol (uE3), and inhibin-A in predicting pregnancy complications other than fetal aneuploidy. Materials and Methods: A retrospective study in 3,121 singleton pregnancies with integrated testing was performed at Kangnam CHA hospital between January 2005 and December 2006. Baseline characteristics, pregnancy outcomes, and serum marker levels were obtained by review of the medical records. We analyzed the data to identify associations between the integrated screening markers and adverse pregnancy outcomes. Statistical analyses were performed with the SPSS program. Results: In preterm labor and preeclampsia, high AFP, hCG, and inhibin-A levels and low PAPP-A and NT levels were found to be significantly correlated (P<0.05). Elevated second-trimester inhibin-A levels were associated with preeclampsia (odds ratio 2.843), low birth weight (odds ratio 1.446), and preterm labor (odds ratio 1.287), and while decreased first-trimester PAPP-A levels were associated with preeclampsia (odds ratio 0.51) and preterm labor (odds ratio 0.75). Conclusion: First- and second-trimester maternal serum markers screening can be used for predicting high-risk pregnancies.