• Journal of Periodontal and Implant Science
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• v.42 no.6
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• pp.217-223
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• 2012

Purpose: Several parameters have been described for determining the success or failure of dental implants. The surface properties of transgingival implant components have had a great impact on the long-term success of dental implants. The purpose of this study was to compare the tendency of two periodontal pathogens to adhere to and colonize zirconia abutments and titanium alloys both in hard surfaces and soft tissues. Methods: Twelve patients participated in this study. Three months after implant placement, the abutments were connected. Five weeks following the abutment connections, the abutments were removed, probing depth measurements were recorded, and gingival biopsies were performed. The abutments and gingival biopsies taken from the buccal gingiva were analyzed using real-time polymerase chain reaction to compare the DNA copy numbers of Aggregatibacter actinomycetemcomitans, Porphyromonas gingivalis, and total bacteria. The surface free energy of the abutments was calculated using the sessile water drop method before replacement. Data analyses used the Mann Whitney U-test, and P-values below 0.05 find statistical significance. Results: The present study showed no statistically significant differences between the DNA copy numbers of A. actinomycetemcomitans, P. gingivalis, and total bacteria for both the titanium and zirconia abutments and the biopsies taken from their buccal gingiva. The differences between the free surface energy of the abutments had no influence on the microbiological findings. Conclusions: Zirconia surfaces have comparable properties to titanium alloy surfaces and may be suitable and safe materials for the long-term success of dental implants.

• Korean Journal of Materials Research
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• v.31 no.12
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• pp.690-696
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• 2021

The purpose of this study is to develop a zirconium-based alloy with low modulus and magnetic susceptibility to prevent the stress-shielding effect and the generation of artifacts. Zr-7Cu-xSn (x = 1, 5, 10, 15 mass%) alloys are prepared by an arc melting process. Microstructure characterization is performed by microscopy and X-ray diffraction. Mechanical properties are evaluated using micro Vickers hardness and compression test. The magnetic susceptibility is evaluated using a SQUID-VSM. The average magnetic susceptibility value of the Zr-7Cu-xSn alloy is 1.176 × 10^-8 cm³g^-1. Corrosion tests of zirconium-based alloys are conducted through polarization test. The average Icorr value of the Zr-7Cu-xSn alloy is 0.1912 ㎂/cm². The elastic modulus value of 14 ~ 18 GPa of the zirconium-based alloy is very similar to the elastic modulus value of 15 ~ 30 GPa of the human bone. Consequently, the Sn added zirconium alloy, Zr-7Cu-xSn, is very interesting and attractive as a biomaterial that reduces the stress-shielding effect caused by differences of elastic modulus between human bone and metallic implants. In addition, this material has the potential to be used in metallic dental implants to effectively eliminate artifacts in MRI images due to low magnetic susceptibility.

• Resources Recycling
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• v.21 no.1
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• pp.60-65
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• 2012

The Ti-6Al-4V alloys were prepared by recycling of dental Ti pure scraps using vacuum arc melting process, and their physical properties were evaluated the Ti-6Al-4V alloys with different oxygen concentrations. For the preparation of Ti-6Al-4V alloys, Ti pure scraps used for dental implant were utilized as a raw material, and their different oxygen concentrations were ranged from G1 to G4 grade in ASTM standards. It was confirmed that the weight loss of Al in the composition of Ti-6Al-4V alloy could be controlled under the Ar pressure of 875 torr during the melting of alloy. The oxygen concentrations of the Ti-6Al-4V alloys were ranged from 1170 to 3340 ppm. The vickers hardness change of the Ti-6Al-4V alloys showed a similar behavior with that of pure Ti. As a result, we confirmed a possibility of preparation of Ti-6Al-4V alloy by recycling of dental Ti scraps using vacuum arc melting process in this study.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.21 no.12
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• pp.434-439
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• 2020

Selective laser melting (SLM) manufactures an alloy using laser as a heat source, and has recently been introduced in the dental industry. However, there is a lack of analytical research on metal-ceramic restorations achieved by SLM. This study evaluates and compares the metal-ceramic bond strength of Co-Cr alloys produced by selective laser melting and casting methods. Co-Cr samples required for this study were produced through the sintering process of ceramics, by applying the SLM and CAST methods. The metal-ceramic bond strength was measured by applying the shear bond strength test. In order to determine the area fraction of adherent ceramic, Si content of the specimen was measured using scanning electron microscopy SEM/ EDS. Results of the metal-ceramic bond strength and AFAC were analyzed by t-test (α = 0.05). No significant difference was observed comparing the bond strength of SLM and CAST Co-Cr alloys (P> 0.05). However, the SLM group had much better ceramic adherence than the CAST group (P < 0.001). Moreover, oxidation characteristics were similar for both SLM and CAST Co-Cr alloys, but metal structures were different. These results imply that although the bond of ceramic and Co-Cr alloy is not related to the manufacturing method, SLM alloys impart better ceramic adherence. This indicates that alloys made with SLM can be used to fabricate upper implant prostheses in the future. In particular, it is expected to overcome the shortcomings of the CAST method, and save time and cost.

• Journal of Technologic Dentistry
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• v.31 no.1
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• pp.55-61
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• 2009

Passive fitting of meso-structure and super-structures is a predominant requirement for the longevity and clinical success of osseointegrated dental implants. However, precision and passive fitting has been unpredictable with conventional methods of casting as well as for corrective techniques. Alternative to conventional techniques, electro discharge machining(EDM) is an advanced method introduced to dental technology to improve the passive fitting of implant prosthesis. In this technique material is removed by melting and vaporization in electric sparks. Regarding the efficacy of EDM, the application of this technique induces severe surface morphological and elemental alterations due to the high temperatures developed during machining, which vary between $10,000{\sim}20,000^{\circ}C$. The aim of this study was to investigate the morphological and elemental alterations induced by EDM process of casting dental gold alloy and non-precious alloy used for the production of implant-supported prosthesis. A conventional clinical dental casting alloys were used for experimental specimens patterns, which were divided in three groups, high fineness gold alloy(Au 75%, HG group), low fineness gold alloy(Au 55%, LG group) and nonprecious metal alloy(Ni-Cr, NP group). The UCLA type plastic abutment patterns were invested with conventional investment material and were cast in a centrifugal casting machine. Castings were sandblasted with $50{\mu}m\;Al_2O_3$. One casting specimen of each group was polished by conventional finishing(HGCON, LGCON, NPCON) and one specimen of each group was subjected to EDM in a system using Cu electrodes, kerosene as dielectric fluid in 10 min for gold alloy and 20 min for Ni-Cr alloy(HGEDM. LGEDM, NOEDM). The surface morphology of all specimens was studied under an energy dispersive X-ray spectrometer (EDS). The quantitative results from EDS analysis are presented on the HGEDM and LGEDM specimens a significant increase in C and Cu concentrations was found after EDM finishing. The different result was documented for C on the NPEDM with a significant uptake of O after EDM finishing, whereas Al, Si showed a significant decrease in their concentrations. EDS analysis showed a serious uptake of C and Cu after the EDM procedure in the alloys studied. The C uptake after the EDM process is a common finding and it is attributed to the decomposition of the dielectric fluid in the plasma column, probably due to the development of extremely high temperatures. The Cu uptake is readily explained from the decomposition of Cu electrodes, something which is also a common finding after the EDM procedure. However, all the aforementioned mechanisms require further research. The clinical implication of these findings is related with the biological and corrosion resistance of surfaces prepared by the EDM process.

• 연구논문집
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• s.30
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• pp.137-145
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• 2000

Since the concept of osseointegration was introduced, titanium and titanium-based alloy materials have been increasingly used for bone-anchored metal in oralmaxillofacial and orthopedic reconstruction. Successful osseointegration has been attributed to biocompatibility and surface condition of metal implant among other factors. Although titanium and titanium alloys have an excellent over the metal ion release and biocompatibility, considerable controversy has developed over the metal ion and wear debris in vivo and vitro. In this study, nitrogen ion implantation technique was used to improve the corrosion resistance and wear property of titanium materials, ultimately to enhance the tissue reaction to titanium implants As ion implantation energy was increased, projected range of nitrogen ion the Ti substrate was gradually increased. Under condition of constant ion energy. atomic concentration of nitrogen was also increased with ion doses. The friction in Hank's solution was increased with ion doses. The friction coefficient of ion implanted specimens in HanK's solution was increased from 0.39, 0.47 to 0.52, 0.65 respectively under high energy and ion dose conditions. As increasing ion energies and ion dose, amount of wear was reduced.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.18 no.9
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• pp.418-424
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• 2017

Magnesium has a higher specific strength than other metals and is widely used industry wide due to its excellent vibration absorption ability and electromagnetic wave shielding property.For example, it is used for automobile parts such as car seat frames and cylinder heads, and is widely used in electronic products such as notebook cases and mobile phone cases. In addition, it is in the spotlight as a bone-implant material used to assist in the treatment of damaged bones when the bones are cracked or broken. Currently, Ti alloy, stainless steel and Co-Cr-Mo alloy are used as the implant material, and the Mg alloy remains in research stage. The current problem with bone implant implants is that the patients must undergo reoperation to remove the implants after joint surgery. Magnesium, however, can achieve sufficient strength compared to current materials. In addition, since it is self-decomposed after the recovery, reoperation is not necessary. In this paper, Mg alloys were designed by adding harmless Ca and Zn to the human body. In order to improve the strength and corrosion resistance, the final alloy was designed by adding a small amount of Sr as a grain refiner. The radioactive elements of Sr are harmful to the human body, but other naturally occurring Sr elements are harmless. Microstructure analysis of the alloys was performed by optical microscopy and scanning electron microscopy. The mechanical properties and corrosion characteristics were evaluated by tensile test, potentiodynamic test and immersion test.

• Proceedings of the Korean Institute of Surface Engineering Conference
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• 2018.06a
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• pp.75-75
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• 2018

Commercially pure titanium (CP-Ti) and Ti-6Al-4V alloys have been widely used in implant materials such as dental and orthopedic implants due to their corrosion resistance, biocompatibility, and good mechanical properties. However, surface modification of titanium and titanium alloys is necessary to improve osseointegration between implant surface and bone. Especially, when titanium oxide nanotubes are formed on the surface of titanium alloy, cell adhesion is greatly improved. In addition, plasma electrolytic oxide (PEO) coatings have a good safety for osseointegration and can easily and quickly form coatings of uniform thickness with various pore sizes. Recently, the effects of bone element such as magnesium, zinc, strontium, silicon, and manganese for bone regeneration are researching in dental implant field. The purpose of this study was researched on the surface morphology of PEO-treated Ti-6Al-4V alloy after anodic titanium oxide treatmentusing various instruments. Ti-6Al-4V ELI disks were used as specimens for nanotube formation and PEO-treatment. The solution for the nanotube formation experiment was 1 M $H_3PO_4$ + 0.8 wt. % NaF electrolyte was used. The applied potential was 30V for 1 hours. The PEO treatment was performed after removing the nanotubes by ultrasonics for 10 minutes. The PEO treatment after removal of the nanotubes was carried out in the $Ca(CH_3)_2{\cdot}H_2O+(CH_3COO)_2Mg{\cdot}4H_2O+Mn(CH_3COO)_2{\cdot}4H_2O+Zn(CH_3CO_2)_2Zn{\cdot}2H_2O+Sr(CH_2COO)_2{\cdot}0.5H_2O+C_3H_7CaO_6P$ and $Na_2SiO_3{\cdot}9H_2O$ electrolytes. And the PEO-treatment time and potential were 3 minutes at 280V. The morphology changes of the coatings on Ti-6Al-4V alloy surface were observed using FE-SEM, EDS, XRD, AFM, and scratch tester. The morphology of PEO-treated surface in 5 ion coating solution after nanotube removal showed formation or nano-sized mesh and micro-sized pores.

• Proceedings of the Korean Institute of Surface Engineering Conference
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• 2017.05a
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• pp.157-157
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• 2017

Titanium and its alloys that have a good biocompatibility, corrosion resistance, and mechanical properties such as hardness and wear resistance are widely used in dental and orthopedic implant applications. They can directly connect to bone. However, they do not form a chemical bond with bone tissue. Plasma electrolytic oxidation (PEO) that combines the high voltage spark and electrochemical oxidation is a novel method to form ceramic coatings on light metals such as titanium and its alloys. This is an excellent reproducibility and economical, because the size and shape control of the nano-structure is relatively easy. Silicon (Si), manganese (Mn), and magnesium (Mg) has a useful to bone. Particularly, Si has been found to be essential for normal bone, cartilage growth and development. Manganese influences regulation of bone remodeling because its low content in body is connected with the rise of the concentration of calcium, phosphates and phosphatase out of cells. Insufficience of Mn in human body is probably contributing cause of osteoporosis. Pre-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. The objective of this work was to study nucleation and growth of bone-like apatite formation on Ti-6Al-4V in solution containing Mn, Mg, and Si ions after plasma electrolytic oxidation. Anodized alloys was prepared at 270V~300V voltages. And bone-like apatite formation was carried out in SBF solution for 1, 3, 5, and 7 days. The morphologies of PEO-treated Ti-6Al-4V alloy in containing Mn, Mg, and Si ions were examined by FE-SEM, EDS, and XRD.

• Korean Journal of Materials Research
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• v.24 no.2
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• pp.111-115
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• 2014

Titanium and its alloys are useful for implant materials. In this study, porous Ti-Nb-Zr biomaterials were successfully synthesized by powder metallurgy using a $NH_4HCO_3$ as space holder and $TiH_2$ as foaming agent. Consolidation of powder was accomplished by spark plasma sintering process(SPS) at $850^{\circ}C$ under 30 MPa condition. The effect of high energy milling time on pore size and distribution in Ti-Nb-Zr alloys with space holder($NH_4HCO_3$) was investigated by optical microscope(OM), scanning electron microscope(SEM) & energy dispersive spectroscopy(EDS) and X-ray diffraction(XRD). Microstructure observation revealed that, a lot of pores were uniformly distributed in the Ti-Nb-Zr alloys as size of about $30-100{\mu}m$ using mixed powder and milled powders. In addition, the pore ratio was found to be about 5-20% by image analysis, using an image analyzer(Image Pro Plus). Furthermore, the physical properties of specimens were improved with increasing milling time as results of hardness, relative density, compressive strength and Young's modulus. Particularly Young's modulus of the sintered alloy using 4h milled powder reached 52 GPa which is similar to bone elastic modulus.