• The Journal of Korean Academy of Prosthodontics
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• v.49 no.2
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• pp.161-167
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• 2011

Purpose: The purpose of this study was to evaluate the influence of porcelain re-firing on the formation of surface bubble and on the change in shade of metal-ceramic crown exposed to artificial saliva. Materials and methods: Thirty disk-shaped specimens were made in 10 mm diameter with 0.5 mm metal core thickness and 1 mm ceramic thickness. A spectroradiometer was used to determine the CIE Lab coordinates. The number and size of surface bubble were observed with a stereomicroscope. After the exposure to artificial saliva for 7 days, re-firing was performed at glazing temperature. After re-firing, the CIE Lab were calculated, and the number and size of surface bubble were observed again. The change in shade was expressed with ${\Delta}E$. Statistical analysis was done with paired t-test for the change in the number of surface bubble and student t-test for the change in the size of surface bubble (${\alpha$}=0.05). Results: Shade difference was calculated 2.14 ${\Delta}E$ units. The mean number of surface bubble was $1.33{\pm}1.49$ before re-firing, $3.27{\pm}2.90$ after re-firing. After re-firing, the number of surface bubble was significantly increased (P<.05). The mean size of surface bubble was $81.97{\pm}32.03\;{\mu}m$ before re-firing, $142.94{\pm}47.40\;{\mu}m$ after re-firing. After re-firing, the size of surface bubble was significantly increased (P<.05). Conclusion: Shade change after re-firing was perceptible (${\Delta}E$ < 2.0) and clinically acceptable (${\Delta}E$ < 3.7). The number and size of surface bubble was significantly increased after re-firing. Further investigation to decrease the surface bubble on the extra oral repair of metal-ceramic crown, will be needed in future study.

• The Journal of Korean Academy of Prosthodontics
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• v.49 no.2
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• pp.128-137
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• 2011

Purpose: Resonance frequency analysis, Periotest, and removal torque (RT) test were known as the methods to assess implant stability. The results of these methods are affected by the bone condition, implant diameter and shape. The purpose of this study is to access the meaning and the correlationship of the resonance frequency analysis, Periotest and RT test in osseointegration simulated acrylic resin when the engaged bone thickness and peri-implant bone defect are changed. Materials and methods: To simulate osseointegration, the fixture was fixed to an aluminum mold with a screw. Acrylic resin powder and liquid were poured into the mold for polymerization. The engaged resin thickness with implant was controlled. Simulated cortical bone thicknesses were 1, 3, 5 and 10 mm. Additional 1, 3 and 5 mm peri-implant bone defects were simulated. Three types of implants were used; 4 mm diameter implants of straight shape, 4 mm diameter implants of tapered shape and 5 mm diameter implants of tapered shape. Five fixtures per each type were tested in respective bone condition. Resonance frequency analysis and Periotest were evaluated in all bone conditions. Peak removal torque was measured at simulated cortical bone thicknesses of 1 and 3 mm. The statistical analysis was performed with the Kruskal-Wallis test, Mann-Whitney U test, and Spearman test using a 95% level of confidence. Results: With increasing engaged bone depth, the Implant Stability Quotient (ISQ) values increased and the Periotest values (PTVs) decreased (P<.001, P<.001). With increasing peri-implant bone defect, ISQ values decreased and PTVs increased (P<.001). When the diameter of implant increased, ISQ values increased and Periotest values (PTV) decreased (P<.001). There was a strong correlation between ISQ values and PTVs (r = -0.99, P<.001). Furthermore, the peak removal torque values had weak correlations with both ISQ values and PTVs (r = 0.52, P<.001 ; r = -0.52, P<.001). Conclusion: This study confirmed favorable implant stability with increasing engaged bone depth and implant diameter and decreasing peri-implant bone defect. ISQ values and PTVs showed strong correlation with each other and not with the peak removal torque values.

• The Journal of Korean Academy of Prosthodontics
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• v.46 no.2
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• pp.201-208
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• 2008

Statement of problem: A new implant impression technique which use abutments as impression coping, and use resin cement as a splinting material was described. Accuracy of this technique was compared with conventional closed tray and resin splinted open tray technique for a $15^{\circ}$ angled 3-implant model Material and methods: A dental stone master model with 3 linearly positioned implant analogue and a reference framework which was passively fitted to it were fabricated. The center analogue was perpendicular to the plane of model and the outer analogues had a $15^{\circ}$angulation forward or backward. 10 closed tray impressions, 10 resin splinted open tray impressions, 10 abutment-resin framework cementation impressions and 10 abutment-metal framework cementation impressions were made with additional silicone material and poured with dental stone. A light microscope with image processing was used to record the vertical gap dimension between reference framework and analogue of duplicated cast made with each 4 impression techniques. Statistical analysis used one-way ANOVA with post-hoc tests Tukey test of .05 level of significance Results: Significant difference in the vertical gap dimension was found between closed tray technique; 74.3 (${\pm}33.4$)${\mu}m$ and resin splinted open tray technique, and two other new technique. (P<.05) Abutment-metal framework cementation technique;42.5 (${\pm}11.9$)${\mu}m$ was significantly different from resin splinted open tray technique. (P<.05) Abutmentresin framework cementation technique;51.0 (${\pm}14.1$)${\mu}m$ did not differ significantly from resin splinted open tray technique;50.3 (${\pm}16.9$)${\mu}m$. (P>.05) Conclusion: Within limitations of this study, the accuracy of implant level impressions of resin splinted open tray technique was superior to that of closed tray technique. A new technique using abutment and metal framework cementation was more accurate than resin splinted open tray technique.

• The Journal of Korean Academy of Prosthodontics
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• v.46 no.2
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• pp.169-174
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• 2008

Statement of problem: Changes of the marginal bone around dental implants have significance not only for the functional maintenance but also for the esthetic success of the implant. It was proposed that bone-retention elements such as microthreads at the coronal part of implant might help maintain the marginal bone level. Purpose: This study was designed to evaluate the effect of microthread configuration within the marginal coronal portion of the implant fixture at the marginal bone changes after loading around two different external hex implants. Material and methods: Twenty-four patients were included and randomly assigned to treatment with $Br{{\aa}}nemark$ system implants (Group 1, rough-surfaced implants, n=20) and Oneplant system implants (Group 2, rough-surfaced neck with microthreads, n=20). Clinical and radiographic examinations were conducted at baseline (implant loading) and 1 year postloading. Data analysis was performed by the SAS statistical package version 9.1.3 (SAS Institute, Cary, NC, USA) and the final model was calculated by the MIXED procedure (three-level ANCOVA) for marginal bone change of each test group at baseline and 1 year follow-up. Results: Comparing to baseline, significant differences were noted in marginal bone level changes for the 2 groups at 1 year follow-up (P<0.05). Group 1 had a mean crestal bone level changes of $0.83{\pm}0.31mm$; Group 2 had a mean crestal bone level changes of $0.44{\pm}0.36mm$. Rough-surfaced with microthreads implants showed significantly less marginal bone loss than rough surfaced neck without microthread implants. Conclusion: A rough surface with microthreads at the implant was beneficial design to maintain the marginal bone level against functional loading.

• The Journal of Korean Academy of Prosthodontics
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• v.58 no.3
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• pp.207-216
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• 2020

Purpose: To compare the polishing characteristics and their influence on Candida albicans adhesion to the recently introduced polyetherketoneketone (PEKK) and the conventional polymethylmethacrylate (PMMA) denture resin material. Materials and methods: Specimens from PEKK (Group E) and PMMA (Group M) were made in dimensions of 8 mm in diameter and 2 mm in thickness. The specimens were further divided into sub-groups according to the extent of polishing (ER, MR: rough; EP, MP: polished, N = 12 each). The specimens were polished using polishing machine and SiC foil. ER and MR group specimens were polished with 600 grit SiC foil only. EP and MP groups were further polished with 800, 1,000, 1,200 grit SiC foils sequentially. To measure the surface roughness values (Sa) of specimens, atomic force microscope (AFM) was used and scanning electron microscope (SEM) observation under 1,000, and 20,000 magnifications was performed to investigate surface topography. The polished specimens were soaked in C. albicans suspension for 2 hours with shaking to promote adhesion. The attached C. albicans were detached from the surface with 10 times of pipetting. The suspension of detached C. albicans was performed by serial dilution to 10³ times, and the diluted suspensions were inoculated on Sabouraud dextrose agar plates using spread plate method. After incubating the plate for 48 hours, colony forming unit (CFU)/plate of C. albicans was counted. Statistical analysis was performed using one-way ANOVA and Tukey HSD test to confirm significant difference between the groups (α=.05). Results: Average Sa value was significantly higher in MR group compared to other groups (P<.05), meaning that additional polishing steps reduced surface roughness effectively only in the PMMA specimens. There was no significant difference in Sa values between MP and EP groups. In SEM images, PEKK specimens showed numerous spikes of abraded material protruding from the surface and this phenomenon was more significant in EP group. The mean CFU/plate value was the highest in EP group and this was significant when it was compared to MP group (P<.05) which was the lowest. Conclusion: Polishing PEKK using serial SiC abrasive foil may result in higher adhesion of C. albicans. In clinic, this should be considered carefully.

• Journal of Radiation Protection and Research
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• v.32 no.2
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• pp.89-96
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• 2007

Radiation safety managements in medical institutions are needed to protect certain radiation damages as a part of National Coalition. This study investigates the characteristics of self-efficacy that become the major factor on the knowledge, attitude, and behavior on the radiation safety management of radiation workers as an approach of educational aspects and analyzes the relationship between such factors to provide basic materials for improving the activity level of radiation safety managements. In order to implement the goal or this study, a survey was performed for 1,200 workers who were engaged in radiation treatments in medical centers, such as general hospital, university hospital, private hospital, and public health center for 42 days from July 23,2006. Then, the results of the analysis can be summarized as follows: 1. Average scores on knowledge, attitude, and behavior in the radiation safety management were presented as $75.76{\pm}11.20$, $90.55{\pm}8.59$, $80.58{\pm}11.70$, respectively. Also, the average score of self-efficacy was recorded as $73.55{\pm}9.82$. 2. Knowledge levels in the radiation safety management showed significant differences according to the sex, age, marriage, education, and experience. Also, males of married, older, highly educated, and largely experienced represented high knowledge levels. Attitude levels in the radiation safety management showed certain significant differences according to the type of medical centers in which private hospitals showed a relatively low level compared to that of high levels in university hospitals. Behavior levels in the radiation safety management also represented significant differences according to the age, marriage, education, experience, and types of medical centers. Factors in married, general hospital, older, highly educated, and largely experienced showed high behavior levels. In addition, the self-efficacy showed certain differences according to the marriage and types of medical centers. Factors in married and general hospital demonstrated high self-efficacy levels. 3. Relationship between knowledge, attitude, behavior, and self-efficacy on the radiation safety management showed statistical differences according to the relationship between the knowledge and the attitude, the knowledge and the behavior, the attitude and the behavior, the attitude and the self-efficacy, and the behavior and the self-efficacy. The relationship between the behavior and the self-efficacy was represented as r = 0.482, which was the strongest relationship in such factors. Also, the knowledge and self-efficacy didn't show certain relationships.

• Child Health Nursing Research
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• v.2 no.2
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• pp.45-57
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• 1996

A serious disease in a family influences the entire family member given the fact that the members closely interact with each other. Especially in terms of pediatric nursing, study on family gains importance as the need to care of families whose children with developmental disabilities and chronic disease This study was done based on The Resiliency Model of Family Adjustment and Adaptation(McCubbin, 1991) is intended to examine the stress of parents whose children suffer from cleft lip or /and cleft palate. It also helps them to cope with the stress and analyze the relationship between the stress and coping This study used Family Inventory of Life Events and Changes (FILE) and Coping Health Inventory for Parents(CHIP) for measuring family stress and coping. The two instruments are revised to fit the social and cultural environment of Korean culture. Data collection was done from April 18, 1996 to May 18, 1996 at 8 University medical centers located in Seoul. Those who answered questionnaires were 84 parents whose children have cleft lip or /and cleft palate. SPSS PC+ was used to analyze the data collotted. Programs used for data analysis were t-test, ANOVA, Pearson correlation coefficient. The study is summarized as follows .1. The average score of family stress is 10.46(percentage of the full score 24.90) and 'finance and business strains'(3.25), and 'intrafamily strains'(2.65) ranked the highest. The average score of family's coping is 1.93, which is close to the answer of' moderately helpful' and they are measured to put their utmost efforts to' intergration and cooperation of family and optimistic definition on the situation'. 2. There is no significant statistical correlation between the family stress and coping. 3. Mothers show more stress than fathers in the parts of 'illness and family care strains' and 'losses'(t〓-2.34, t〓-2.32, p<.05). 4. Fathers show more willingness to cope with the stress than mothers do in the parts of' seeking social support','self-esteem','emotional comfort' 5. Mothers are more stress than fathers in the parts of family stress and its coping with it by usual traits(t〓-2.78, p<.05). Parents with religion are measured to cope more willingly than those who are not 6. Income of a family shows positive correlationship with family coping (r〓.28, p<.05). The study shows that gender difference is significant variable in studying on family stress and coping. Mothers get more stress than fathers, which has much to do with the fact that they are in charge of raising children and keeping houseworks. Accordingly, managing family crisis and its survival can be induced by giving support for the mothers, studying fathers including the rest of the family members and giving nursing care and arbitration ; religious background is also considered to be one of the important factors in family stress , judging from the relationship between family income and family's coping, caring given to suffering children is needed on societal levels. The above considerations bring up the need to have a longitudinal study of children with congenital anomaly including cleft lip or /and cleft palate and their families about family stress and coping. Resiliency programs on family system and their effectiveness and the relationship between the enlarged families with social and cultural values reflecting Korean tradition are also needed to be studied.

• Clinical and Experimental Reproductive Medicine
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• v.34 no.4
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• pp.285-291
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• 2007

Objective: To evaluate the outcomes of in vitro fertilization and embryo transfer (IVF-ET) in women over 40 years of age. Methods: A total of 170 patients (271 cycles) over 40 years of age who underwent IVF-ET at Seoul Women's Hospital (Incheon, Korea) were analyzed in this study retrospectively. The patients were grouped into the women <44 years old group and the women $\geq$44 years old group. Statistical analysis was performed using Student's t-test and Fisher's exact test as appropriate. Results: An overall clinical pregnancy rate per retrieval was 11% (30/271). Of these, clinical miscarriage rate were 33% (10/30) and the overall delivery rate was 7.4% (20/271) per retrieval, respectively. The women $\geq$44 years old group had significantly higher cancellation rate (13% vs. 25%), lower number of retrieved oocytes (6.17$\times$4.62 vs. 4.13$\times$4.07), decreased number of 2PN (4.83$\times$3.61 vs. 3.46$\times$3.12), and reduced embryos for transfer (3.52$\times$1.72 vs. 2.81$\times$1.83) than the women <44 years old group. We found significantly lower clinical pregnancy rate (13.0% vs. 2.1%) and live birth rate (9.0% vs. 0.0%) in the women $\geq$44 years old group than the women <44 years old group. Conclusion: The present study has shown that IVF outcome is seriously impaired in the women $\geq$44 years old.

• Clinical and Experimental Reproductive Medicine
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• v.34 no.4
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• pp.305-312
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• 2007

Objective: To evaluate the efficacy of split insemination method in treatments for non-male factor infertility. Method: Laboratory and clinical data were collected from 505 cycles of split insemination during 2002$\sim$2005 in our center. The subjects were non-male factor infertility such as endometriosis, tubal, uterine, PCOS and idiopathic infertility without any sperm defects. Retrieved oocytes were randomly divided, and inseminated by conventional IVF or ICSI. Fertilized zygotes were cultured for 2$\sim$5 days to ET date, and surplus zygotes and embryos were frozen for subsequent frozen-thawed ET cycles. Clinical outcomes according to insemination method were compared by statistical analysis. Results: The overall fertilization per retrieved oocytes was significantly higher in ICSI than that of conventional IVF in sibling oocytes (62.5$\pm$22.3% vs 52.9$\pm$28.0%, p<0.01). Total fertilization failure occurred only in 2 of 505 cycles (0.4%) in split insemination cycles. Incidence of fertilization failure and poor fertilization rate less than 30% by ICSI were significantly lower than those of conventional IVF (1.1% and 7.5% vs 8.5% and 22.0%, p<0.01). Delivery rates after transfer of fresh and thawed embryos from split insemination cycles were 40.0% (185/462) and 35.0% (55/157), respectively. There was no significant difference in the implantation and delivery rates of ET with embryos from conventional IVF or ICSI. Conclusion: Taken together, the split insemination method improves poor fertilization rates resulting in successful clinical outcomes and thus could be used for non-male factor infertile couples in human ART program.

• Clinical and Experimental Reproductive Medicine
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• v.34 no.2
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• pp.125-131
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• 2007

Objective: The aim of this study was to compare GnRH antagonist and agonist flare-up treatment in the management of poor responder patients. Methods: One hundred forty-four patients from Jan. 1, 2002 to Aug. 31, 2005 undergoing IVF/ICSI treatment who responded poorly to the previous cycle (No. of oocyte retrieved$\leq$5) and had high early follicular phase follicle stimulating hormone (FSH>12 mIU/ml were selected. Seventy-five patients received agonist flare-up protocol and 71 patients received antagonist protocol. We analyzed the number of oocytes retrieved, number of good embryos (GI, GI-1), total dose of hMG administered, implantation rate, cycle cancellation rate, pregnancy rate, live birth rate. Results: The cancellation rate was high in antagonist protocol (53.5% vs. 30.1%). The number of oocyte retrieved, the number of good embyos were high in agonist flare-up group. There was no statistical difference between GnRH agonist flare up protocol and GnRH antagonist protocol in implantation rate (14.5%, 10.1%), clinical pregnancy rate per transfer (29.4%, 21.2%) and live birth rate per transfer (21.6%, 18.2%). Although the result was not statistically significant, GnRH agonist flare up group showed a nearly doubled pregnancy rate and live birth rate per initial cycle than GnRH antagonist group. Conclusions: The agonist flare-up protocol appears to be slightly more effective than the GnRH antagonist protocol in implantation rate, pregnancy rate, live birth rate but shows statistically no significance. Agonist flare-up protocol improved the ovarian response in poor responders. However, based of the result of the study, we can expect improved ovarian response in poor responders by GnRH agonist flare up protocol.