• 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.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.

• 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.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.

• Journal of Gastric Cancer
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• v.6 no.4
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• pp.214-220
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• 2006

Purpose: p53 is one of the most commonly mutated genes in human tumors. The aim of this study was to analyze p53 mutation in gastric cancer and its correlations with the clinicopathologic variables to clarify the usefulness of p53 mutation as a prognostic factor. Materials and Methods: Specimens from 331 patients with gastric cancer who underwent a gastrectomy between March 1999 and April 2001 at the Kyungpook National University Hospital were used. p53 gene mutations were assessed by using a polymerase chain-reaction single-strand conformation polymorphism (PCR-SSCP) analysis. The correlations between p53 gene mutation and clinocopathologic parameters were analyzed. Results: p53 mutations were found in 66 (19.9%) tumors. Among those 66 cases, mutations were seen in 23 tumors at axon 5, in 8 at exon 6, in 21 at exon 7, and in 17 at exon 8. Two mutations were shown in 3 tumors. Thiriy-six (23.1%) of 156 intestinal-type tumors and 19 (13.1%) of 145 diffuse-type tumors showed p53 gene mutation (P=0.007). The frequency of p53 gene mutation didn't show any significant differences according to age, sex, stage, location, or gross type. Exon 5 mutations showed more frequently in intestinal-type tumors than in diffuse-type tumors (9.7% vs. 2.8%, P=0.024), and p53 mutation were more frequent in lymph nodes metastasis group than lymph nodes non-metastasis group with statistical significance (25.0% vs 15.6%, P=0.034). The five-year survival rate showed no statistically significant difference with p53 mutation (P=0.704). Conclusion: p53 mutations assessed by PCR-SSCP had little value as a prognostic factor after gastrectomy in patients with gastric cancer.

• Journal of Gastric Cancer
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• v.6 no.4
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• pp.244-249
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• 2006

Purpose: Tumor size has been reported to be one of the prognostic factors in the preoperative setting and 8 cm has been confirmed as a cut-off value for large gastric tumors with respect to postoperative complications. The aim of this study was to investigate the clinicopathologic features and the prognosis in patients with tumors larger than 8 cm in diameter. Materials and Methods: We retrospectively studied 2,260 patients with gastric cancer who underwent a gastrectomy from 1983 to 2001 at the Department of Surgery, Korea University College of Medicine. For a comparative analysis we divided the cases into the large and the small groups according to tumor size. The clinicopathological factors associated with large gastric tumors were analyzed by using univariate and multivariate analyses. To determine which variables were independent prognostic factors for overall survival, we applied the Cox proportional hazards model and we used P<0.05 as the cutoff value for statistical significance. Results: Univariate and multivariate analyses disclosed that tumor location (P<0.001), resection type (P<0.001), curability (P<0.001), depth of invasion (P<0.001), number of metastatic lymph nodes (P<0.001), differentiation (P<0.001) and combined resection (P<0.001) were significantly different between the two groups. The independent factors for survival identified by using the Cox proportional hazards model for large gastric tumors were nodal status (P<0.001), curative resection (P<0.001), depth of invasion (P=0.010), type of resection (P=0.018) and age (P=0.033). Conclusion: Large gastric tumors showed more aggressive local findings than their smaller counterparts. In patients with large gastric tumors, a curative resection was the most important factor for the prognosis. Therefore, we suggest that every effort should be made to do a curative gastrectomy and an accurate preoperative examination. (J Korean Gastric Cancer Assoc 2006;6:244-249)

• Journal of Gastric Cancer
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• v.6 no.4
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• pp.250-256
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• 2006

Purpose: Recently, interest in peroxisome-proliferator-activated receptors (PPAR) has increased, although clinical studies of the effect of $PPAR-{\gamma}$ expression on gastric cancer have not been reported yet. In this study, we investigated the role of $PPAR-{\gamma}$ expression in gastric cancer patients. Materials and Methods: One hundred twenty-eight (128) samples of both gastric cancer and normal tissues were obtained from 128 patients who had undergone at a curative gastrectomy at Seoul Medical Center from Jan. 2001 to Dec. 2005. $PPAR-{\gamma}$ expression was determined by using immunohistochemical staining, and the results were analyzed. The statistical analysis was based on clinicopathological findings and the differences in survival rates. Results: The mean age of the patients was 6n, and the male : female ratio was 1.9 : 1. $PPAR-{\gamma}$ expression was significantly higher in cancer tissues than in normal tissue (81.3% vs. 57.0%, p<0.001). There was insignificant difference between well and moderately differentiated types and poorly differentiated types in terms of the expression of $PPAR-{\gamma}$ (87.0% vs. 74.6%, P=0.074). In the univariate analysis the survival rate was significantly increased when $PPAR-{\gamma}$ was expressed in normal tissue (P=0.003). In the multivariate analysis, only the UICC TNM staging had significance related to the survival rate. Conclusion: The rate of $PPAR-{\gamma}$ expression was higher in cancer tissue than it was in normal tissue from gastric cancer patients. In the univariate analysis, $PPAR-{\gamma}$ expression in normal tissue had significance with respect to survival, but the multivariate analysis showed no such significance. Thus, we should further evaluate more cases to determine whether or not such a significance exists.

• Journal of Gastric Cancer
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• v.9 no.1
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• pp.18-25
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• 2009

Purpose: The postoperative hospital stay after gastric cancer surgery is usually 8 to 14 days. The main reason for a prolonged hospital stay may be the 3 to 4 day period of postoperative starvation. The aim of this study is to investigate the feasibility of a critical pathway for early recovery after gastric cancer surgery, and this pathway included early postoperative feeding. Materials and Methods: One hundred three consecutive patients who underwent gastric resection and reconstruction for gastric cancer from October 2007 to June 2008 at St. Mary's Hospital were prospectively enrolled in a fast-track critical pathway. The pathway included minimal preoperative procedures, optimal pain relief, proper fluid administration, early mobilization and early enteral nutrition at postoperative 1 day. The exclusion criteria were determined preoperatively, intraoperatively and postoperatively. Results: Of the 103 patients, 19 patients were excluded for preoperative (5), intraoperative (7) and postoperative (7) reasons. Eighty-four patients (81.6%) were included in the fast-track critical pathway. Sixty-eight (88.6%) of 84 patients were discharged at the planned 8 day after surgery during the initial period of the study, and the postoperative hospital stay was shortened up to 6 days during the more recent period. Postoperative complications occurred in 22 patients (26.2%), and these were gastrointestinal track-related complications in 6 cases (3 cases of ileus, 1 case of stasis and 2 cases of leakage) and infection-related complications in 8 cases. There was no statistical difference in the incidence of morbidity according to the clinic-operative features that included age, gender, stomach resection and lymphadenectomy. Conclusion: The fast-track critical pathway with using the available exclusion criteria was a valid option for patients who underwent gastric cancer surgery.