• Composites Research
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• v.13 no.4
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• pp.42-53
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• 2000

A study has been made to establish an optimum condition in the surface treatment and curing method that is important for the fabrication of Al 7075/CFRP laminates. PAA(Phosphoric Acid Anodizing) provided a good adhesive strength and FPL(Sulfuric / Sodium Dichromate Acid Etching) had a similar adhesive strength with PAA. On the other hand, the poor adhesive strength was shown on vapor degrease and CAA(Chromic Acid Anodizing). By using the atomic force microscope(AFM), it was found that the PAA oxide surface obviously had a greater degree of microroughness as compared to vapor degrease, CAA and FPL treated surfaces. These results support the concept of a mechanical interlocking of the adhesive with-in the oxide pores as the predominant adhesion mechanism. In curing methods, the adhesive strength of co-curing method was higher than that of secondary curing method. With respect to stability of specimen shape, the secondary curing method was better than co-curing method. DMA(Dynamic Mechanical Analysis) test revealed $T_g$ in curing times over 60 min is nearly same, so it is estimated they will have similar degree of curing and joint durability in using FM300M adhesive film.

• Journal of Periodontal and Implant Science
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• v.29 no.3
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• pp.561-578
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• 1999

The goal of periodontal therapy is the periodontal regeneration by the removal of microorganisms and their toxic products from the periodontally diseased root surface. To achieve periodontal regeneration, root conditioning as an adjunct to root planing has been done. There are low pH etchants such as citric acid, tetracycline-HCl, and EDTA solution which is a neutral chelating agent. The purpose of present study was to examine the effect of root conditioning by citric acid, tetracycline HCl, and EDTA. Total 35 root specimens(6${\times}$3${\times}$2mm) were prepared from the periodontally diseased teeth, scaled and root planed. The specimens were treated with normal saline for 1 minute, saturated citric acid(pH 1) for 3 minutes, 50mg/ml tetracycline-HCl(pH 2) for 5 minutes, 15% EDTA(pH 7) for 5 minutes using rubbing technique. The specimens were examined under scanning electron microscopy at 1000, and 3000 magnification. On the microphotographs taken at 1000 magnification, the numbers of opened and patent dentinal tubules per unit area(10,640${\mu}m^2$) were counted. And the diameters of opened dentinal tubules per unit are (10,640${\mu}m^2$) were measured. The differences of number and diameter among all groups were statistically analyzed by Kruskal Wallis Test. The results were as follows; 1. In the specimens applied with normal saline(control group), the root surface was finely cracked, and was covered by irregular smear layer. Neither exposed dentinal tubules nor any patent dentinal tubules could be seen. 2. In the specimens applied with saturated citric acid(experimental 1 group), the globular collagen fibers were exposed around the peritubular space, and many dentinal tubules were revealed. 3. In the specimens applied with tetracycline-HCl(experimental 2 group), the process-like collagen fibers were exposed around the peritubular space, and some dentinal tubules were revealed. 4. In the specimens applied with 15% EDTA(experimental 3 group), the root surface was covered by the collagenous fibrillar network, and many dentinal tubules were revealed. 5. The numbers of opened and patent dentinal tubules were significantly more in exp. 1 group and exp. 3 group than in exp. 2 group(P<0.05). But there was no significant difference between exp. 1 group and exp. 3 group. In control group, the number of opened and patent dentinal tubules could not be counted because any dentinal tubules couldn't be seen. 6 . The diameter of opened dentinal tubules was significantly smaller in exp. 1 group and exp. 3 group than in exp. 2 group(P<0.05). But there was no significant difference between exp. 1 group and exp. 3 group. In control group, the diameter of opened dentinal tubules could not be measured because any dentinal tubules couldn't be seen. The results demonstrate that root conditioning with citric acid, tetracycline- HCl, and EDTA is more effective in periodontal healing than only root planing, and 15% EDTA solution can replace low pH etching agents such as citric acid, tetracycline-HCl for root conditioning.

• Journal of the korean academy of Pediatric Dentistry
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• v.34 no.4
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• pp.569-578
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• 2007

This study was performed to compare the shear bond strength of self etching system and two bottle bonding system with or without laser preparation. Group I was prepared with high speed rotary instrument and $Prompt^{TM}$ L-$Pop^{TM}$, group II with Er:YAG laser and $Prompt^{TM}$ L-$Pop^{TM}$, group III with Er:YAG laser, 37% phosphoric acid and Single bond, group IV with Er:YAG laser and Single bond and group V with high speed, etching and Single bond. And also observation of the prepared and etched dentin surface were performed under scanning electro-microscope. The possibility of clinical application of laser preparation which might have an advantage to reduce pain for children with less unfavorable noise were evaluated. The results obtained are as follows; 1. Group V showed significantly higher bond strength than other groups. And group IV showed significantly lower bond strength than other groups. 2. There was no significant difference between group I and group III. 3. Group II showed significantly lower bond strength than group I, III, V, but showed significantly higher bond strength than group IV. 4. Under scanning electro-microscope, laser-preparated dentin surface showed high irregularity and no smear layer. The surface showed less irregularities and more exposed dentinal tubules with etching. Laser preparation has many advantages over conventional tooth preparation. But this method showed lower resin bonding strength. Laser preparated tooth surface differed from the conventionally preparated tooth surface. More researches are needed on suitable methods for laser preparated dentin surface.

• The korean journal of orthodontics
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• v.26 no.4
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• pp.389-399
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• 1996

Remineralization of acid-etched enamel across the time has been one of the curiosities in the context of the orthodontic biomechanics(Arends J. et al., IRL Press, 1, 1985), nevertheless, is so far controversial. It was the aim of this study to observe the remineralization patterns of acid-etched enamel across the time and whether the existence of fluoride might carry out any modifications. The intact buccal surfaces of the first bicuspids which was extracted for orthodontic treatment were ground smooth, and etched with a 38w/w% phosphoric acid for 60 seconds, The surface was observed by the scanning electron microscope and surface microhardness was measured after immersion in the fluoride or non-fluoride containing remineralizing solution for 0 hour, 12 hours, 1 day, 3 days, 7 days, 14 days, 28 days, and 42 days. The following results and conclusions were drawn; 1. Surface microhardness increased in both fluoride containing and non-fluoride containing solution group with time lapse. 2. In fluoride containing solution group, the surface microhardness sharply increased at the 12 hours group, on the other hand, surface microhardness increased at 3 days in non-fluoride containing solution group. 3. The difference in microhardness value between two groups manifested gradual decrease. 4. Scanning electron microphotographs disclosed that the fluoride containing solution group generated spiculate sub-stances in the 12 hours group, which was increased in number and size with time lapse. 7 days later, spherical composure was began to be produced, The spiculate substances so much increased in number that the etched enamel surface looked like flat in 42 days. 5. In non fluoride-containing solution group, there was no surface change at 42 days, perceivable in scanning electron microphotographs which could be defined as remineralization though the surface was a little rougher than the incipient etched surface. These results demonstrate that the action of the fluoride is exceedingly pertinent in the remineralization of acid-etched enamel and the remineralization process goes uninterruptedly with time lapse.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.18 no.3
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• pp.101-104
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• 2008

GaN films were grown on the vertical and horizontal reactors by the hydride vapour phase epitaxy (HVPE). The structural and optical characteristics of the GaN films were investigated depending on the reactor-type. GaN epilayers were characterized by double crystal X-ray diffraction (DC-XRD), transmission electron microscopy (TEM) and photoluminescence (PL). Surface defects of two kinds of the GaN films were revealed by the wet chemical etching method, using $H_3PO_4$ acid at $200^{\circ}C$ for 8 minutes. Hexagonal etch pits were analyzed by optical microscopy and SEM. Etch pit densities were calculated to be approximately $1.4{\times}10^7$ and $1.2{\times}10^6\;cm^{-2}$ for GaN layers grown on horizontal and vertical reactors, respectively. Those results show GaN grown in the vertical reactor having a better quality of optical properties and crystallinity than that in the horizontal reactor.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.39 no.12
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• pp.1297-1303
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• 2015

The internal chromium plating of a long-axis tube is widely used in military and industrial application, with the thick hard plating formed using a mixed solution of Chromium acid and catalytic $H_2SO_4$. A large-caliber gun can endure a high explosive force as a result of the increased stiffness and wear resistance provided by this internal hard chromium surface. The internal chromium layer of a tube is prone to exfoliation caused by the high kinetic energy of the projectile and high pressure of the explosion. Therefore, we reviewed the plating process. Chromium plating comprises many steps, including the removal of Grease, water cleaning, electrolytic abrasion, etching, plating, water cleaning, and hydrogen brittleness removal. The exfoliated chromium plating layer is affected by the adhesion property of the plating. In particular, the Fe concentration of the electrolyte affects the adhesion property. The optimum Fe concentration for effectively suppressing the exfoliation of the plating layer was established by using a scanning electron microscope to determine the surface roughness, and the effectiveness was proved in an adhesion test, etc.

• The Journal of Korean Academy of Prosthodontics
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• v.43 no.3
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• pp.393-408
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• 2005

Statement of problem. In the process of bone formation, titanium (Ti) surface roughness is an important factor modulating osteoblastic function. Purpose. This study was carried out to determine the effect of different Ti surface on biologic responses of a human osteoblast-like cell line (MG63). Materials and methods. MG63 cells were cultured on S (smooth), SLA (sandblasted largegrit & acid etching), HA (hydroxyapatite) Ti. The morphology and attachment of the cells were examined by SEM. The cDNAs prepared from total RNAs of MG63 were hybridized to a human cDNA microarray (1,152 elements). Results. The appearances of the surfaces observed with SEM were different in the three types of dental substrates. The surface of SLA and HA were shown to be rougher than S. MG63 cells cultured on SLA and HA were cell-matrix interaction. In the expression of genes involved in osseointegration, upregulated genes were bone morphogenetic protein, Villin, Integrin, Insulin-like growth factors in different surfaces. Downregulated genes were fibroblast growth factor receptor 4, Bcl 2-related protein, collagen, CD4 in different surfaces. Conclusion. The attachment and expression of key osteogenic regulatory genes were enhanced by surface roughness of the dental materials.

• Maxillofacial Plastic and Reconstructive Surgery
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• v.34 no.3
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• pp.186-199
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• 2012

Purpose: Single implants, of which screw loosening has been observed frequently, presents problems such as fixtures fractures, marginal bone loss, and inflammation of the soft tissue around the implant. However, the single implant is more conservative, cost effective, and predictable compared to the 3 unit bridge with respect to the long-term outcome. This study evaluated the survival rate as well as future methods aimed at increasing the survival rate in single implants in posterior teeth. Methods: Among the implants placed in the Dankook University Dental Hospital department of Oral & Maxillofacial surgery from January 2001 to June 2008, 599 implants placed in the maxillar and mandibular posterior were evaluated retrospectively. Survival rates were investigated according to implant location, cause of tooth loss, gender, age, general disease, fixture diameter and length, surface texture, implant type and shape, presence of bone graft, surgery stage, surgeons, bone quality and opposite teeth. Results: Out of 599 single implants in posterior teeth, 580 implants survived and the survival rate was 96.8%. The difference in survival rate was statistically significant according to the implant location. The survival rate was low (84.2%) in implants exhibiting a wide diameter (${\geq}5.1mm$) and the surface treated by the acid etching group demonstrated a significantly lower survival rate (91.1%). One stage surgical procedure, which implemented a relatively better bone quality survival rate (100%), was higher than the two stage surgical procedure (96.1%). The survival rate of type IV bone quality (75%) was significantly lower than the other bone quality. Conclusion: Single posterior teeth implant treatments should use an improved surface finishing fixture as well as careful and safe procedures when performing implant surgery in the maxilla premolar and molar regions since bone quality is poor.

• Journal of Periodontal and Implant Science
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• v.38 no.4
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• pp.595-602
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• 2008

Purpose: Ti-6Al-4V alloy is widely used as an implant material because of its good biocompatibility and good mechanical property compared with commercial pure titanium. Otherwise, toxicity of aluminum and vanadium in vivo has been reported. Ti-8Ta-3Nb alloy is recently developed in the R&D Center for Ti and Special Alloys and it was reported that this alloy has high mechanical strength, no cytotoxicity and similar biocompatibility to commercial pure titanium, but many studies are needed for its clinical use. In these experiment, we carried out different surface treatment on each Ti-8Ta-3Nb alloy disks, then cultured cell on it and assessed biological response. Materials and Methods: cpTi, Ti-6Al-4V, Ti-8Ta-3Nb alloy disks were prepared and carried out sandblasting and acid etching (SLA) or alkali-heat treatment (AH) on the Ti-8Ta-3Nb alloy disks. We cultured primary rat calvarial cells on each surface and assessed early cell attachment and proliferation by scanning electron microscopy, cell proliferation, alkaline phosphatase activity. Result: The rates of cell proliferation on the cpTi, Ti-8Ta-3Nb AH disks were higher than others (p<0.05) and alkaline phosphatase activity was significantly enhanced on the Ti-STa-8Nb AH disks(p<0.05). Conclusion: Most favorable cell response was shown on the Ti-8Ta-3Nb AH surfaces. It is supposed that alkali-heat treatment of the Ti-8Ta-3Nb alloy could be induced earlier bone healing and osseointegration than smooth surface.

• Journal of the korean academy of Pediatric Dentistry
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• v.44 no.1
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• pp.82-88
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• 2017

The purpose of this study is to investigate shear bond strengths of $Peak^{(R)}$ Universal Bond (Ultradent, USA) containing 0.2% chlorhexidine in bovine dentin. Total of 30 bovine teeth were divided into three groups, 10 teeth each. Before comparing and evaluating shear bond strength, in group I, $Adper^{TM}$ Single Bond Universal (3M ESPE, USA) was applied, in group II, processing with $Consepsis^{(R)}$ (Ultradent, USA) was followed by applying $Adper^{TM}$ Single Bond Universal, and in group III, $Peak^{(R)}$ Universal Bond was applied and filled with $Filtek^{TM}$ Z-350 XT (3M/ESPE, USA) shade B3. As a result, processing with $Consepsis^{(R)}$ after acid etching showed no statistically significant influence on shear bond strength of dentin (p > 0.05). The shear bond strength of with or without $Consepsis^{(R)}$ on $Adper^{TM}$ Single Bond Universal and that of $Peak^{(R)}$ Universal Bond showed statistically significant difference (p < 0.05).