• Proceedings of the Korean Institute of Surface Engineering Conference
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• 2017.05a
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• pp.152-152
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• 2017

Titanium and its alloys have been widely used for biomedical applications. However, the use of the Ti-6Al-4V alloy in biomaterial is then a subject of controversy because aluminum ions and vanadium oxide have potential detrimental influence on the human body due to vanadium and aluminum. Hence, recent works showed that the synthesis of new Ti-based alloys for implant application involves more biocompatible metallic alloying element,such as, Nb, Hf, Zr and Mo. In particular, Nb and Hf are one of the most effective Ti ${\beta}$-stabilizer and reducing the elastic modulus. Plasma electrolyte oxidation (PEO) is known as excellent method in the biocompatibility of biomaterial due to quickly coating time and controlled coating condition. The anodized oxide layer and diameter modulation of Ti alloys can be obtained function of improvement of cell adhesion. Silicon (Si) and magnesium (Mg) has a beneficial effect on bone. Si in particular has been found to be essential for normal bone and cartilage growth and development. In vitro studies have shown that Mg plays very important roles in essential for normal growth and metabolism of skeletal tissue in vertebrates and can be detected as minor constituents in teeth and bone. Therefore, in this study, Si and Mg coatings on the hydroxyapatite film formed Ti-29Nb-xHf alloys by plasma electrolyte oxidation has been investigated using several experimental techniques. Ti-29Nb-xHf (x= 0, 3, 7 and 15wt%, mass fraction) alloys were prepared Ti-29Nb-xHf alloys of containing Hf up from 0 wt% to 15 wt% were melted by using a vacuum furnace. Ti-29Nb-xHf alloys were homogenized for 2 hr at $1050^{\circ}C$. The electrolyte was Si and Mg ions containing calcium acetate monohydrate + calcium glycerophosphate at room temperature. The microstructure, phase and composition of Si and Mg coated oxide surface of Ti-29Nb-xHf alloys were examined by FE-SEM, EDS, and XRD.

• Journal of Technologic Dentistry
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• v.23 no.1
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• pp.65-73
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• 2001

The purpose of this study was to investigate the microstucture and hardness, corrosion of pure Ti alloy, which is widely used as partial denture frame work these days, depending on the cooling method, followed by casting. The first group was bench cooling at room temperature($18^{\circ}C$), the second group was slowly cooled in the furnace from $700^{\circ}C$ to room temperature, and third. rapidly cooled in $0^{\circ}C$ water. The microstructure of each specimen observed by means of photomicrograph taken by electron microscope, in add to the physical characteristics of each specimen were obtained using the rockwell Hardnest Number. the characteristics of corrosion. The results were obtained as follows: 1. From Potentiodynamic plot. we conclude furnace-cooled specimen had the best stabiltity of passive film and that air-cooled specimen showed similar characteristics. The density of electric current of quenched specimen was the highest, which formed kind of unstable passive film. 2. Specimen cooled at room temperature (air cooling) had the highest value of hardness of 81.26HRB, specimen cooled at ice-water, $0^{\circ}C$, had the value of 78.42HRB, and specimen furnace-cooled at $700^{\circ}C$ had lowest value of 77.1HRB. 3. Quenching treated micro-structure formed martensite structure by and large. In case of air cooling, we could see $\alpha$-structure widmanstatten formed overall. In furnace cooling, widmanstatten structure and various shape $\alpha$-structures forming colony with direction were detected.

• Restorative Dentistry and Endodontics
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• v.47 no.2
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• pp.16.1-16.9
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• 2022

Objectives: This study compared the cyclic fatigue resistance of One Curve (C wire) and F6 Skytaper (conventional austenite nickel-titanium [NiTi]), and 2 instruments with thermos-mechanically treated NiTi: Protaper Next X2 (M wire) and Hyflex CM (CM wire). Materials and Methods: Ten new instruments of each group (size: 0.25 mm, 6% taper in the 3 mm tip region) were tested using a rotary bending machine with a 60° curvature angle and a 5 mm curvature radius, at room temperature. The number of cycles until fracture was recorded. The length of the fractured instruments was measured. The fracture surface of each fragment was examined with a scanning electron microscope (SEM). The data were analyzed using one-way analysis of variance and the post hoc Tukey test. The significance level was set at 0.05. Results: At 60°, One Curve, F6 Skytaper and Hyflex CM had significantly longer fatigue lives than Protaper Next X2 (p < 0.05). No statistically significant differences were found in the cyclic fatigue lives of One Curve, F6 Skytaper, and Hyflex CM (p > 0.05). SEM images of the fracture surfaces of the different instruments showed typical features of fatigue failure. Conclusions: Within the conditions of this study, at 60° and with a 5 mm curvature radius, the cyclic fatigue life of One Curve was not significantly different from those of F6 Skytaper and Hyflex CM. The cyclic fatigue lives of these 3 instruments were statistically significantly longer than that of Protaper Next.

• Journal of Dental Rehabilitation and Applied Science
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• v.27 no.1
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• pp.73-79
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• 2011

Purpose of this experiment is to evaluate the effect of titanium on the castability when the titanium is added to the Co-Cr alloy. Raw materials Cobalt, Chrome, Molybdenum, Silicon, Manganase, Carbon, Nitrogen, Titanium were weighted and prepared. $Biosil^F$ (Degudent, Germany) was the control group. To the experimental group, different weight percent of titanium was added from 1 wt% to 4 wt%. The wax pattern is $30{\times}40$ cm in size, rectangular in shape and has total of 160 grids. Centrifugal machine (Neutrodyne Easy Ti: Manfredy) was used for casting. For evaluation of the castability, the number of complete grids was counted by visual inspection and X-ray inspection. The test showed similar castability with the control group in the titanium addition of 1 wt% to 3 wt%. The titanium addition of 4 wt% showed poor result. With titanium lower than 4 wt%, the experiment metals showed proper castability with high expectation of successful clinical use.

• The Journal of Korean Academy of Prosthodontics
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• v.17 no.1
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• pp.23-34
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• 1979

In this study, the adhesive strength of three commercial polycarboxylate cements to ten types of dental casting alloys, such as gold, palladium, silver, indium, copper, nickel, chromium, and human enamel and dentine were measured and compared with that of a conventional zinc phosphate cement. The $8.0mm{\times}3.0mm$ cylindrical alloy specimens were made by casting. The enamel specimens were prepared from the labial surface of human upper incisor, and the dentine specimens were prepared from the occulusal surface of the human molar respectively. Sound extracted human teeth, which had been kept in a fresh condition since, extraction, were mounted in a wax box with a cold-curing acrylic resin to expose the flattened area. The mounted teeth were then placed in a Specimen Cutter (Technicut) and were cut down under a water spray, and then the flat area on the all specimens were ground by hand with 400 and 600 grit wet silicone carbide paper. Two such specimens were then cemented together face-to-face with freshly mixed cement, and moderate finger pressure was applied to squeeze the cement to a thin and uniform film. All cemented specimens were then kept in a thermostatic humidor cabinet regulated at $23{\pm}2^{\circ}C.$ and more than 95 per cent relative humidity and tested after 24 hours and 1 week. Link chain was attached to each alloy specimen to reduce the rigidity of the jig assembly, and then all the specimens were mounted in the grips of the Instron Universal Testing Machine, and a tensile load was delivered to the adhering surface at a cross head speed of 0.20 mm/min. The loads to which the specimens were subjected were recorded on a chart moving at 0.50 mm/min. The adhesive strength was determined by measuring the load when the specimen separated from the cement block and by dividing the load by the area. The test was performed in a room at $23{\pm}2^{\circ}C.$ and $50{\pm}10$ per cent relative humidity. A minimum of five specimens were tested each material and those which deviated more than 15 per cent from the mean were discarded and new specimens prepared. From the experiments, the following results were obtained. 1) It was found that the adhesive strength of the polycarboxylate cement to all alloys tested was considerably greater than that of the zinc phosphate cement. 2) The adhesive strength of the polycarboxylate cements was superior to the non precious alloys, such as the copper, indium, nickel and chromium alloys, but it was inferior to the precious gold, silver and palladium alloys. 3) Surface treatment of the alloy was found to be an important factor in achieving adhesion. It appears that a polycarboxylate cement will adhere better to a smooth surface than to a rough one. This contrasts with zinc phosphate cements, where a rough helps mechanical interlocking. 4) The adhesion of the polycarboxylate cement with enamel was found superior to its adhesion with dentine.

• Journal of Dental Rehabilitation and Applied Science
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• v.21 no.2
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• pp.95-103
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• 2005

Purpose: Recently, various metal primers have been developed, and these are known to increase the bond strength between metal and relining resin. In this study, the change in bond strength according to amount of thermocycling was evaluated. Materials and Methods: In this study, 216 specimens were fabricated. Tokuyama Rebase $II^{(R)}$(Tokuyama Corp., Japan) and $Kooliner^{(R)}$(GC America Inc., Japan) as relining material, and MR. $Bond^{(R)}$(Tokuyama Corp., Japan) and Alloy $Primer^{(R)}$(Kuraray Medical Inc., Japan) as a metal primers were used. Using Ni-Cr and various metal surface treatment methods, resin was bonded and the change in bond strength during thermocycling was measured. The data was analyzed by one-way ANOVA, t-test(p<.05 level of significance). Results: When comparing the groups with only sandblasting, rapid decrease in shear bond strength could be seen. In the groups using Tokuyama Rebase $II^{(R)}$, with the exception of the 1000 and 2000 cycle groups, each group showed statistically significant decrease in shear bond strength(p<0.05). In comparison according to relining materials, $Kooliner^{(R)}$ showed higher shear bond strength than Tokuyama Rebase $II^{(R)}$ in all groups. In groups using MR $bond^{(R)}$, $Kooliner^{(R)}$ had higher shear bond strength than Tokuyama Rebase $II^{(R)}$ but, there was no statistical significance(p<0.05). In the other groups, $Kooliner^{(R)}$ showed significantly higher shear bond strength(p<0.05). There was significant difference between groups with sandblasting and metal primer treatments(p<0.05). In comparison according to metal primer materials, Alloy $Primer^{(R)}$ showed the highest shear bond strength but there was no statistical significance(p>0.05). According to the number of thermocycling cycles, when using Tokuyama Rebase $II^{(R)}$, there were no significant differences between the 0, 1000 and 2000 cycle groups regardless of the type of metal primer. There were no differences between the 2000 and 3000 cycle groups. When using $Kooliner^{(R)}$, regardless of the type of metal primer, there were no significant differences between the 0, 1000, 2000 and 3000 cycle groups(p>0.05). Conclusion: The use of metal primers showed increase in bond strength, and the stability after to thermocycling has been authenticated. Thus, the use of metal primers in relining and rebasing of metal frameworks is essential. But when selecting the material various physical properties should be considered.

• The Journal of Korean Academy of Prosthodontics
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• v.28 no.2
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• pp.53-76
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• 1990

The purpose of this study was to evaluate the tensile bond strength of adhesive resins to successively recast Rexillium III and Degudent-U. Recasting was done 4times successively. Specimen $A_1$, were cast by new metal, and $A_2$ by surpus of $A_1$, $A_3$ by surplus of, $A_2$ $A_4$ by surplus of $A_3$, $A_5$ by surplus of $A_4$ plus 50% new metal. The types of surface treatment for resinbonded restoration in this experiment were electrolytic etching by OXY-ETCH(Oxy dental products, Inc., Hillside, New Jersey, U.S,A.), aluminum oxide blasting, anodic oxidation by EZ-OXISOR( Towagiken Co., Kyoto, Japan), electrotinplating by Kura Ace(Kuralay Co., Kyoto, Japan). Three kinds of cementing resin used in this study were Comspan(K.P. Cauil Co, Milford Delaware, U.S.A.), Super Bond C&B(Sun-Medical Co. Ltd., Kyoto,Japan), Panavia EX(Kuralay Co., Ltd., Osaka, Japan). Tensile bond strength was measured by Instron Universal testing machineModel 1125) and all the specimen were observed with SEM(JEOL, JSM-T2000) and mode of bond failure were recorded. The obtained results were as follows : 1. In electrolytic etched group, tensile bond strength was decreassed when recast alloy was used, and tensile bond strength of Compan and panavia EX were not significantly different(P>0.05). 2. In remaining group treated by aluminum oxide blasting, EZ-OXIOR, Kura Ace, tensile bond strength were not changed when recast alloy were used, and tensile bond strength of SuperBond(C&B and Panavia EX were not significantly different(P>0.05). 3. IN SEM evaluation, electrolytic etched group and electrotinplated group exhibited different image when recast alloy was used, and remaining groups treated by aluminum oxide blasting, EZ-OXISOR exhibited the same. 4. IN observation of bond failure, electrolytic etched group exhibited adhesive failure and remaing groups treated by aluminium oxid blasting, EZ-OXISOR, Kura Ace exhibited adhesive and cohesive failure.

• Journal of Dental Rehabilitation and Applied Science
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• v.24 no.2
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• pp.129-146
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• 2008

The aim of this study was to compare and analyze wear resistance of acrylic resin tooth in denture opposing to different types of restoration materials. Also, it aimed to compare and analyze the hardness of three various types of resin artificial teeth when using five different types of denture detergents. In this study three types of artificial teeth were used. As ordinary acrylic resin tooth $Trubyte^{(R)}Biotone^{(R)}$ (Dentsply, U.S.A.) was used, and as high hardness resin tooth Endura $Posterio^{(R)}$ (Shofu, Japan) and Physio $Duracross^{(R)}$ (Nissin, Japan) were used. To compare wear resistance, gold alloy, dental porcelain, and composite resin were used as opposing restorations. In addition, with three types of resin tooth stated above, five types of denture detergents, which are $Yuhanrox^{(R)}$ (Yuhanclorox, Korea), $Polident^{(R)}$ (Yuhan Co., Korea), $Cidex^{(R)}OPA$ (Johnson & Johnson Medical Co., Korea), $Hexamedin^{(R)}$ (Bukwang Pharm Co., Korea) and Daihan sterile $water^{(R)}$ (Daihan Pharm Co., Korea) were used to compare and analyze the effects denture detergents have on the surface hardness. The results of this study were as follow : 1. When composite resin and dental porcelain were used as the opposing restorations, $Trubyte^{(R)}$ $Biotone^{(R)}$, Endura $Posterio^{(R)}$, Physio $Duracross^{(R)}$ in ascending order showed decrease of cusp height with significant difference (p<0.05). 2. When gold alloy was used as opposing restoration, there was decrease in the cusp height in order of $Trubyte^{(R)}Biotone^{(R)}$, Endura $Posterio^{(R)}$, Physio $Duracross^{(R)}$ and $Trubyte^{(R)}$ $Biotone^{(R)}$ especially showed significant decrease in high cusp height as compared to two other types of artificial tooth (p<0.05). 3. When composite resin, gold alloy and dental porcelain were used as opposing restorations, $Trubyte^{(R)}$ $Biotone^{(R)}$, Endura $Posterio^{(R)}$, Physio $Duracross^{(R)}$ in order decreased greatly in weight and these three materials showed significant difference (p<0.05). 4. Comparing the experiment values, decrease in strength had significant difference in all resin artificial teeth before and after the denture detergents were used (p<0.05). 5. When resin artificial teeth were subsided in $Yuhanrox^{(R)}$, $Cidex^{(R)}OPA$, and $Hexamedin^{(R)}$, $Trubyte^{(R)}$ $Biotone^{(R)}$, Endura $Posterio^{(R)}$, Physio $Duracross^{(R)}$ in order showed decrease in hardness, and $Trubyte^{(R)}$ $Biotone^{(R)}$ especially showed significant high decrease hardness as to other two types of artificial teeth (p<0.05). Therefore, Physio $Duracross^{(R)}$ seems to have superior wear resistance, and together with Endura $Posterio^{(R)}$, it presents excellent hardness as compared to $Trubyte^{(R)}$ $Biotone^{(R)}$. However, since this study is fragmentary, it should be given careful consideration and more study need to be done before making a definitive conclusion.

• The Journal of Korean Academy of Prosthodontics
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• v.38 no.5
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• pp.695-703
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• 2000

The purpose of this study was to evaluate the effects of fabrication and tightening methods of gold cyliner on the preload of the standard abutment. Three linear strain gauges (KFR-02N-120-C1-23, Kyowa, Japan) were mounted longitudinally on the 5.5mm Standard abutment (Nobel Biocare, Sweden) and three kinds of gold cylinders such as, as-received gold cylinder, gold cylinder after casting, and plastic cylinder after casting with type IV gold alloy were connected over the top of the standard abutment. Two kinds of tightening methods, such as manual torque with handhold screwdriver and electronic torque using Electronic torque controller were used to generate preload on the abutment. The result were as follows; 1. The preload generated by tightening cast plastic cylinder with handhold screw driver, was the lowest among the six groups. 2. The preload generated by cast plastic cylinder was lower than those by gold cylinders regardless of the tightening methods. 3. The electronic torque controller produced higher torque values than the handheld screwdriver.

• Restorative Dentistry and Endodontics
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• v.14 no.1
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• pp.199-204
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• 1989

The purpose of this study was to observe the anodic polarization curve from 4 kinds of low copper amalgam (Fine cut alloy, Spheralloy, Aristalloy and Amalcap) and 4 kinds of high copper amalgam (Dispersalloy, Sybraloy Orosphere and Tytin) obtained by using the potentiostat. The specimen made as the direction of manufacturer was stored at room temperature for about 7 days. The standard surface preparation was routinely carried out. The 0.9% saline solution was used as electrolyte in pH 6.8-7.0 at $37^{\circ}C$. The open circuit potential was determined after 30 minutes' immersion of specimen. The scan rate was 1mV/sec and the surface area of amalgam exposed to the solution was 0.785$cm^2$ for each specimen. All potentials reported are with respect to Ag/AgCl eelctrode. The following results were obtained. 1. The corrosion potential of high copper amalgams was higher than one of low copper amalgams, and the current density of high copper amalgam was lower than one of low copper amalgams. 2. The low copper amalgams had the similar pattern of polarization curve, but the high copper amalgams had the different pattern one another. 3. The polarization curve of Orosphere amalgam which is the admixed type was similar to one of low copper amalgam.