• The korean journal of orthodontics
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• v.27 no.3 s.62
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• pp.493-502
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• 1997

This study was conducted to evaluate the tensile bond strength by bonding the dental bracket with Super-bond after treating the surface of dental Nickel-Chromium alloy with sandblasting, sandblasting & tin-plating, respectively, and tin-plating. 10 pieces of Nickel-Chromium alloys with brackets bonded with Super-bond without their surface treatment were sampled as a control group, 20 pieces of Nickel-Chromium alloy brackets bonded with Super-bond after treating them with sandblasting as group I, 20 pieces of Nickel-Chromium alloys tin-plated and bonded with Super-bond after sandblasting as group II, and then 20 pieces of alloys with brackets bonded with Super-bond after tin-plating as group III. The result of those examination and comparison is summarized as follows: 1. Group I showed the mean tensile bond strength of $14.41{\pm}2.24MPa$ which was highest among 4 groups, followed by group III($13.59{\pm}.51MPa$), group II($12.27{\pm}.45MPa$), and control group($10.50{\pm}1.57MPa$), respectively. However, it was shown that there was no statistically significant difference between group I and III, group III and II, and group II and control group(p>0.05). 2. The main failure pattern of those brackets showed that $70\%$ of the control group had an adhesive failure at the bracket-Superbond interface, and $30\%$ at the Nickel-Chromium alloy-Superbond interface, while other groups did the adhesive failure at the bracket-Superbond interface. 3. When examined under SEM, it was shown that adhesives were mostly attached to the surface of the Nickel-Chromium alloy for all groups while a considerable quantity of adhesives were attached to the bracket base. Then, those samples treated only with sandblasting showed the most even and remarkable roughness of their surface.

• The Journal of the Korean dental association
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• v.12 no.6
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• pp.373-375
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• 1974

This is to determine the possibility of penetration of evaporated mercury to periodontal tissue after amalgam filling. Class 5 cavities on upper canine, total 40 teeth from 10 dogs, were prepared and amalgam alloy which contain about 10 Ci of radioactive mercury were inserted. The animals were sacrificed after the experiment. The teeth were routinely decalcified, sectioned, autoradiographed by means of emulsion and stained by H & E. 1. Blackened grains were found along collagen fiber space underneath gingival sulcus floor. 2. Mercury particle deposited more at cervical portion of periodontium than apical portion. 3. Blackened grains were found along the Sharpey's fiber. Crest bone side was more evident than cement side. 4. Mercury penetration to periodontium of non-experimented tooth showed almost same findings as experimented one.

• Proceedings of the KOSOMBE Conference
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• v.1989 no.05
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• pp.9-12
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• 1989

A preliminary study has been conducted to demonstrate the effect of laser heat treatment on Ni Ti alloy dental arch wires ($0.016"\;{\times}\;0.022"$ and $0.018"\;{\times}\;0.026"$, rectangular shape). Changes in mechanical and thermal properties and surface morphologies are investigated by using optical and scanning electron microscope (SEM), energy dispersive x-ray microprobe analysis(EDX), differential scanning calorimeter (DSC), and micro hardness tester. The results indicate that the laser can affect the thermal equilibrium state of the localized surface. Titanium rich surface film is formed by the laser treatment. The surface film and rapidly resolidified underlying structures show better chemical resistance than the matrix material. Phase transition temperatures which are related to shape recovery temperatures are changed after laser treatment. Hardness of resolidified area and heat affected zone are lower than before treatment.

• Journal of Korea Foundry Society
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• v.11 no.6
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• pp.482-490
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• 1991

This study presents the wear characteristics of Ti alloys (Pure Ti, Ti-6Al-4V, Ti-5Al-2.5Sn) fabricated by centrifugal precision casting in an Ohara dental titanium casting machine. It was found that the hardness of the surface region is higher than that of the interior region. It is considered that the oxygen adsorption in the surface region during casting, leads to the interstitial solid solution hardening. Wear resistance incerases in the order of pure Ti, Ti-6Al-4V, Ti-5Al-2.5Sn alloys. The interior hardness value increases in the same order. The specific wear rate increases with applied load and increases monotonously with sliding speed. The Fe transfer from the counterpart material was observed on the worn surface of the Ti-5Al-2.5Sn alloy. Oxidative wear occurs at low sliding speeds and mechanical fracture wear occurs at high sliding speeds.

• The Journal of the Korean dental association
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• v.11 no.5
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• pp.353-358
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• 1973

The purpose of this study was to determine the gingival response to the various restorations for 3 weeks, 5 weeks and 8 weeks respectively after they had been inserted in 42 tooth of 5dogs. The histopathological observation was also performed to evaluate the effect of the variuos restorations on gingival tissue. They inclued gold, copper and nickel-chrome alloy. The following findings were obtained. 1. The gingivae adjacent to the well adapted and polished restorations and their margins with a level of gingival crest were grossly and histopathologically found no specific changes. 2. The gingive adjacent to the ill fitting and unpolished restorations and their margins with subgingival extension of 1 to 1.5mm were not grossly found any changes but hitopathologically, the inflammatory changes. 3. Thee wee no obvious difference in gingival response among the various alloys in histopathological observation.

• Proceedings of the KOSOMBE Conference
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• v.1996 no.05
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• pp.126-129
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• 1996

Morphological changes of the heat treated dental procelain at toy have been investigated with SIM and TDX. The surface indium concentration of specimens increased as the heat treatment temperature and the oxygen partial pressure increased.

• Proceedings of the Korean Institute of Surface Engineering Conference
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• 2015.05a
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• pp.106-106
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• 2015

In this study, we investigated electrochemically formed nanotube shape on ternary Ti-25Ta-xHf alloys with Hf contents. Ti-25Ta-xHf (x=0~15 wt.%) alloys were manufactured by vacuum arc-melting furnace. The obtained ingots were homogenized in an argon atmosphere at $1050^{\circ}C$ for 2h and then water quenching. The specimens were cut from ingots to 4 mm thickness and first ground and polished using SiC paper (grades from #100 to #2000). The anodization treatments on Ti-25Nb-xHf alloys were carried out at room temperature for experiments. The formation of nanotubular film was conducted by electrochemical method in mixed electrolytes with 1 M $H_3PO_4$ + 0.8 wt. % NaF at 30 V for 2 h. The morphologies of nanotube depended on the Hf content in Ti-25Ta-xHf ternary system.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.40 no.5
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• pp.305-311
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• 2016

Induction heating is the process in which an electrically conducting object (usually a metal) is heated by electromagnetic induction through heat generated in the object by eddy currents. The main advantage of an induction heating device is the generation of the heat inside the target object itself. Hence, non-contact and safe heating devices are widely used in many industrial and medical fields. Recently, a new dental implant system was developed using a shape-memory alloy, wherein an artificial tooth could be easily removed from the dental implant by heating. This paper discusses the development of an induction-heating device to remove the dental crown in the new implant system. First, the finite element simulation of electromagnetic and thermal coupling analysis was implemented to obtain the temperature distributions of the target object for various frequencies, input currents, and coil shapes. Based on the simulation results, experiments were conducted by using prototypes, and an induction heating device was developed to remove the dental crown from the implant.

• Journal of the Korean Academy of Esthetic Dentistry
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• v.3 no.1
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• pp.23-31
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• 1995

The All-Bond system is a unique development in the field of adhesive dentistry. It is a universal bonding system that will bond composite to all dental-related surfaces: dentin, enamel, metal alloy (precious and nonprecious), amalgam, porcelain, and composite. It is also the only system that allows use of both the conservative and all-etch techniques. The main purpose of this paper is to explain the features of the All-Bond system. Its chemistry and a working hypothesis are shown as well.

• Proceedings of the Korean Institute of Surface Engineering Conference
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• 2008.11a
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• pp.64-65
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• 2008

본 연구에서는 임상적으로 사용후 파절된 Ni-Ti파일의 표면 거동을 조사해보고 피로파괴수명 연장을 위하여 표면에 TiN/Ti 및 ZrN/Ti를 다층막으로 코팅한 후 표면의 특성을 조사하였다.