• The Journal of Korean Academy of Prosthodontics
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• v.29 no.2
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• pp.225-243
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• 1991

In recent years immediate implantation has been tried by a few clinicians. This study placed IMZ implants in the rabbit femur with and without bony defects around the implant for simulating fresh extraction site. And one group with bony defects used porous hydroxyapatite ganules(HA) to fill if and the other group left the bony defects around the implant. The purpose of this study was to compare the shear bond strength and the bony contact and formation around the implant. Fifteen rabbits were divided into three groups and placed 10 IMZ implants to each group. Implant sites were surgically prepared with IMZ drills kit and implants were placed(Control), artificial bony defect was created with Apaceram drills kit around the implant sites and implants were placed(Experimental I), bony defect was filled with porous hydroxyapatite granules(Experimental II). Thereafter, rabbits were sacrificed at 8th week and specimens were prepared and pushout tested for shear bond strength of bone-implant interface immediately. Undecalcified and decalcified specimens were prepared with Vilanueva and hematoxylin-eosin stain for light microscopic finding. The results of this study were as follows. 1. In the control group, mean shear strength of bone-implant interface was $2.614{\pm}0.680$ MPa, experimental I was $0.664{\pm}0.322$ MPa, and experimental II was $2.281{\pm}0.606$ MPa. There was significant difference between control and experimental I, between experimental I and experimental II, but did not show significant difference between control and experimental II statistically. 2. In the bony formation surrounding IMZ implant of the three groups, that of cortical bone is more advanced than cancellous bone area. 3. In the histological findings of undecalcified specimens, control and experimental II showed more than 50% of bony or osteoid formation at the bony-implant interface. 4. In the histological findings of undecalcified specimens, experimental I showed less than 50% of bony or osteoid formation at the interface, and observed partial bony defect in the coronal zone. 5. In the experimental II group, were observed direct bony contact to hydroxyapatite granules, and infiltration of a few giant cells. 6. No inflammatory responses were seen around the titanium implants and the hydroxyapatite granules.

• The Journal of Advanced Prosthodontics
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• v.3 no.3
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• pp.145-151
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• 2011

PURPOSE. This study was performed to investigate the ability of recombinant human-bone morphogenic protein-2 immobilized on a heparin-grafted bone substrate to enhance the osteoblastic functions. MATERIALS AND METHODS. The Bio-$Oss^{(R)}$, not coated with any material, was used as a control group. In rhBMP-2-Bio-$Oss^{(R)}$ group, rhBMP-2 was coated with Bio-$Oss^{(R)}$ using only deep and dry methods (50 ng/mL, 24 h). In heparinized rhBMP-2-Bio-$Oss^{(R)}$ group, dopamine was anchored to the surface of Bio-$Oss^{(R)}$, and coated with heparin. rhBMP-2 was immobilized onto the heparinized- Bio-$Oss^{(R)}$ surface. The release kinetics of the rhBMP-2-Bio-$Oss^{(R)}$ and heparinized rhBMP-2-Bio-$Oss^{(R)}$ were analyzed using an enzyme-linked immunosorbent assay. The biological activities of the MG63 cells on the three groups were investigated via cytotoxicity assay, cell proliferation assay, alkaline phosphatase (ALP) measurement, and calcium deposition determination. Statistical comparisons were carried out by one-way ANOVA test. Differences were considered statistically significant at $^*$P<.05 and $^{**}$P<.001. RESULTS. The heparinized rhBMP-2-Bio-$Oss^{(R)}$ showed more sustained release compared to the rhBMP-2-Bio-$Oss^{(R)}$ over an extended time. In the measurement of the ALP activity, the heparinized group showed a significantly higher ALP activity when compared with the non-heparinized groups (P<.05). The MG63 cells cultivated in the group with rhBMP-2 showed increased calcium deposition, and the MG63 cells from the heparinized group increased more than those that were cultivated in the non-heparinized groups. CONCLUSION. Heparin increased the rhBMP-2 release amount and made sustained release possible, and heparinized Bio-$Oss^{(R)}$ with rhBMP-2 successfully improved the osteoblastic functions.

• Maxillofacial Plastic and Reconstructive Surgery
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• v.30 no.2
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• pp.205-212
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• 2008

Genetic variation in the human genome occurs on various levels; from the single nucleotide polymorphism to large, microscopically visible chromosome anomalies. It can be present in many forms, including variable number of tandem repeat (VNTRs; e.g., mini- and microsatellites), presence/absence of transposable elements (e.g., Alu elements), single nucleotide polymorphisms, and structural alterations (e.g., copy number variation, segmental duplication, inversion, translocation). Until recently SNPs were thought to be the main source of genetic and phenotypic human variation. However, the use of methods such as array comparative genomic hybridization (array CGH) and fluorescence in situ hybridization (FISH) have revealed the presence of copy number variations(CNVs) ranging from kilobases (kb) to megabases (Mb) in the human genome. There is great interest in the possibility that CNVs playa role in the etiology of common disease such as HIV-1/AIDS, diabetes, autoimmune disease, heart disease and cancer. The discovery of widespread copy number variation in human provides insights into genetic variability among populations and provides a foundation for studies of the contribution of CNVs to evolution and disease.

• Journal of the Institute of Electronics Engineers of Korea SC
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• v.49 no.1
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• pp.29-38
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• 2012

The noise generated in the process of obtaining the medical image acts as the element obstructing the image interpretation and diagnosis. To restore the true image from the image polluted from the noise, the total variation optimization algorithm was proposed by the R.O. F (L.Rudin, S Osher, E. Fatemi). This method removes the noise by fitting the balance of the regularity and fidelity. However, the blurring phenomenon of the border area generated in the process of performing the iterative operation cannot be avoided. In this paper, we propose the adaptive total variation method by mapping the control parameter to the proposed transfer function for minimizing boundary error. The proposed transfer function is determined by the noise variance and the local property of the image. The proposed method was applied to 464 tooth images. To evaluate proposed method performance, PSNR which is a indicator of signal and noise's signal power ratio was used. The experimental results show that the proposed method has better performance than other methods.

• The Journal of Advanced Prosthodontics
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• v.1 no.2
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• pp.85-90
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• 2009

STATEMENT OF PROBLEM. Over the years, resin-bonded fixed partial dentures (RBFPDs) have gone through substantial development and refinement. Several studies examined the biomechanics of tooth preparation and framework design in relation to the success rate of RBFPDs and considered retention and resistance form essential for increase of clinical retention. However, these criteria required preparations to be more invasive, which violates not only the original intentions of the RBFPD, but may also have an adverse effect on retention due to loss of enamel, an important factor in bonding. PURPOSE. The object of this in vitro study was to compare the dislodgement resistance of the new types of RBFPDs, the conventional three-unit fixed partial denture, and conventional design of RBFPD (Maryland bridge). MATERIAL AND METHODS. Fifty resin mandibular left second premolars and second molars were prepared on dentiforms, according to the RBFPD design. After model fabrication (five group, n = 10), prostheses were fabricated and cemented with zinc phosphate cement. After cementation, the specimens were subjected to tensile loading at a cross head speed of 4 mm/min in a universal testing machine. The separation load was recorded and analyzed statistically using one-way analysis of variance followed by Duncan's multiple range test. RESULTS. Group V, the pin-retained RBFPDs, had the highest mean dislodgement resistance, whereas specimens of group II, the conventional RBFPDs, exhibited a significantly lower mean dislodgement resistance compared to the other 4 groups (P <.05). There were no significant differences between group I, III, and IV in terms of dislodgement resistance (P>.05). Group V had the highest mean MPa (N/$mm^2$) (P <.05). There was no significant difference between groups I, II, III and IV (P > .05). CONCLUSION. Within the limits of the design of this in vitro study, it was concluded that: 1. The modified RBFPDs which utilizes the original tooth undercuts and requires no tooth preparation, compared with the conventional design of RBFPDs, has significantly high dislodgement resistance (P < .05). 2. The modified RBFPDs which utilizes the original tooth undercuts and requires minimal tooth preparation, compared with the conventional FPDs, has significantly no difference in retention and dislodgement resistance)(P>.05). 3. The pin-retained FPDs showed a high dislodgement resistance compared to the conventional three-unit FPDs (P<.05).

• Journal of Periodontal and Implant Science
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• v.27 no.3
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• pp.621-631
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• 1997

To verify the effect of subgingival calculus on the periodontal tissues in periodontitis and the effectiveness of supragingival scaling to remove the calculus, 30 teeth from healthy group (Probing pocket depth:$PPD{\leq}mm$: HP group), 15 teeth from moderate group ($4{\leq}PD<7mm$:MP group), 30 teeth from advanced group (PPD>7mm: AP group) were selected and supragingival scaling was performed before extraction of all experimental teeth. After careful extraction, the teeth were cleaned with saline and disclosed with toluidine blue and carefully examined the relationship and distance between the calculus attached on the root surface and periodontal tissues. As a result, it was; 1. The calculus was not discovered on the root surface of teeth in HP group, but was in MP and AP group, mostly on interproximal surface and furca area. The shape of the attached calculus was ovoid, trepazoid and polygonal and the calculus was distributed randomly over the root surface. 2. PPD was more than the distance between the gingival margin to the level of attached connective tissue in AP group rather than in HP and MP group. 3. The length of calculus was $2.7mm{\pm}.44mm$ in HP group and $4.1{\pm}.89in$ AP group. 4. The distance between the apical margin of calculus and the level of attached connective tissue was $2.4{\pm}.33mm$ in MP group and $3.4{\pm}.89mm$ in AP group. 5. The length of subgingival calculus was tended to increase in relation to the probing pocket depth. Therefore, it can be concluded, the calculus in periodontal pocket can not be removed completely with supragingival scaling. As the terminal part of calculus was far away with limited distance from the periodontal tissue, it can be said that the calculus was not a direct factor in destroying the periodontal tissue. In this study, the extent of the plaque was not verified but the location of calculus can be used in clinical practice for complete removal of calculus when the distance relation bewteen calculus and plaque will be known.

• The Journal of Advanced Prosthodontics
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• v.13 no.6
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• pp.385-395
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• 2021

PURPOSE. To characterize the microstructure of three yttria partially stabilized zirconia ceramics and to compare their hardness, indentation fracture resistance (IFR), biaxial flexural strength (BFS), and fatigue flexural strength. MATERIALS AND METHODS. Disc-shaped specimens were obtained from 3Y-TZP (Vita YZ HT), 4Y-PSZ (Vita YZ ST) and 5Y-PSZ (Vita YZ XT), following the ISO 6872/2015 guidelines for BFS testing (final dimensions of 12 mm in diameter, 0.7 and 1.2 ± 0.1 mm in thicknesses). Energy-dispersive X-ray spectroscopy (EDX), X-ray diffraction (XRD) and scanning electron microscopy (SEM) analyses were performed, and mechanical properties were assessed by Vickers hardness, IFR, quasi-static BFS and fatigue tests. RESULTS. All ceramics showed similar chemical compositions, but mainly differed in the amount of yttria, which was higher as the amount of cubic phase in the diffractogram (5Y-PSZ > 4Y-PSZ > 3Y-TZP). The 4Y- and 5Y-PSZ specimens showed surface defects under SEM, while 3Y-TZP exhibited greater grain uniformity on the surface. 5Y-PSZ and 3Y-TZP presented the highest hardness values, while 3Y-TZP was higher than 4Y- and 5Y-PSZ with regard to the IFR. The 5Y-PSZ specimen (0.7 and 1.2 mm) showed the worst mechanical performance (fatigue BFS and cycles until failure), while 3Y-TZP and 4Y-PSZ presented statistically similar values, higher than 5Y-PSZ for both thicknesses (0.7 and 1.2 mm). Moreover, 3Y-TZP showed the highest (1.2 mm group) and the lowest (0.7 mm group) degradation percentage, and 5Y-PSZ had higher strength degradation than 4Y-PSZ group. CONCLUSION. Despite the microstructural differences, 4Y-PSZ and 3Y-TZP had similar fatigue behavior regardless of thickness. 5Y-PSZ had the lowest mechanical performance.

• The Journal of Korean Academy of Prosthodontics
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• v.17 no.1
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• pp.7-21
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• 1979

This investigation was to analyse normal protrusive and lateral condylar pantographic records written on the sagittal plane and to study components of Fisher's angle and their interrelations. The purpose of this study was limited to (1) discussing the significance of sagittal pantographic record in diagnosis of occlusal disease and(2) basing for reasoning validity of measuring Fisher's angle which has been reported so far. As a result followings were concluded. 1. In each protrusive and lateral condylar movement path, five complicate factors such as initial straightness, distributed simple sigmoid type, simple curvature, initial tiny protruding convexity and tiny repeated sigmoid patterns were noted. Generally each condylar movement path was composed of two to three of these factors. 2. The distribution of positional interrelations of protrusive and lateral condylar paths could be divided into five categories; (a) protrusive-upper, (b) completely coinciding, (c) partially initial coinciding, (d) partially inverted crossing, and (e) completely inverting. Among these, protrusive path-upper positioned condyles were prevailed (79.2%). 3. The distribution of interrelations of protrusive and lateral condylar paths could be devided into five categories according to their distances in the course of movement. Among these, opening (95.8%) and paralleling (66.7%) were prevailing. 4. The involved number of characteristic heterogenous patterns of five categories in protrusive and lateral condylar movement recording relations at one simultaneous recordings was limited to three. However, in case of homogeneous patterns were repeated, usually three to four were included. 5. The maximum distance between protrusive and lateral condylar paths was 1.45mm at the location of 4mm advanced position from centric relation point and 3.90mm at the location of protrusive movement terminal. 6. It seemed to be that ,pantographic records should be consulted other clinical symptoms in order to make certain occlusion diagnosis. 7. At the present moment of investigation, expressing Fisher's angle as a degree revealed a lack due to inherent complexity of protrusive and lateral condylar movement paths. 8. The typical pattern of protrusive and lateral condylar paths written on a pantographic sagittal plate might be described as follows; (a) protrusive condylar path should be positioned upwardly, (b) both mainly be simple curvature, (c) interrelations mainly be opening or paralleling. 9. The mean amounts of separation between protrusive and lateral condylar movement path were $0.75{\pm}0.46$ at 4mm advanced location from centric relation and $1.74{\pm}0.64mm$ at the location of protrusive path terminal.

• Journal of Technologic Dentistry
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• v.34 no.2
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• pp.113-119
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• 2012

Purpose: Zirconia blocks for all ceramic dentures are divided into two groups. One is pre-heated block and the other is binder added block. In this study, the possibility of recycling the remained parts of binder added block after CAD/CAM machining with slip casting process was investigated. Methods: Owing to the binder added block contain large amount of organic matter, Binder burn-out was must be carried out before ball milling for preparing the casting slip. Binder burn-out was accomplished at $600^{\circ}C$ for 10 hours. Ball milling was performed with 5mm zirconia ball and 60mm polyethylene bottle. From 0% to 5% at 1% intervals of alumina was added to zirconia powder for preparing slip. Solid casting was achieved with plaster mold. Cast bodies were dried and sintered at $1,500^{\circ}C$ for 1 hour. Linear shrinkage, apparent porosity, water absorption, bulk density, and flexural strength were tested. Microstructures were observed by SEM, EDS and XRD analysis were executed. Results: Optimum slips for casting was prepared with 300g ball, 100g powder, and 180g distilled water. Cast body without alumina showed 26% of linear shrinkage, 6.07 of apparent density, and 470MPa of three point bend strength. On the other hand, as received zirconia block, which was sintered at the same conditions, showed 23% of linear shrinkage, 6.10 of apparent density, and 680MPa of three point bend strength. When 3% of alumina was added to zirconia, sintered body showed 23% of linear shrinkage, 6.10 of apparent density, and 780MPa of three point bend strength. SEM photomicrographs and EDS analysis showed alumina particles uniformly dispersed in zirconia matrix, and XRD analysis showed no phase transformation of tetragonal zirconia particles was occurred when alumina was added. Conclusion: According to the all of this experimental results, 3% of alumina added cast zirconia body showed excellent mechanical properties more than as received binder containing zirconia block.

• Journal of the Korean Chemical Society
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• v.55 no.5
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• pp.875-881
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• 2011

This study examined factors influencing college science learning from the perspectives of college students and high school science teachers. Using a survey created based on focus group interviews, college science majors and high school science teachers rated various factors of high school learning that positively influenced college science learning. Findings suggested that the perceptions differed by college major: the physics major students considered math proficiency and logical thinking skills as the important factors; chemistry major students and biology major students considered English proficiency and basic scientific knowledge as the most important factors. Both college students and science teachers emphasized basic science knowledge and math proficiency. However, differences between the two groups were also found in that the students perceived more need to learn about experimentation than the teachers whereas the teachers had a priority in increasing advanced science content.