• 대한치과보철학회지
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• 제52권1호
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• pp.9-17
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• 2014

연구 목적: 본 연구에서는 외과적으로 형성한 골 결손부에 이종골 이식과 함께 식립한 지르코니아 임플란트의 골유착에 대한 기계적 안정성과 조직학적 반응을 타이타늄 임플란트와 비교하고자 하였다. 연구 재료 및 방법: 6마리 돼지의 경골에 인위적으로 형성한 골 결손 부위에 대조군인 18개의 상용 타이타늄 나사형 임플란트와 실험군인 18개의 샌드블라스팅한 지르코니아(Y-TZP) 나사형 임플란트를 각각 식립하고 차폐막을 이용하여 이종골을 이식하였으며 1주, 4주, 12주후에 각각 2마리씩 희생시켜 조직 시편을 제작하였다. 식립 직후와 식립 1주, 4주, 12주 후에 각각 페리오테스트를 이용하여 임플란트의 안정성을 측정하였고, 광학현미경으로 조직학적 관찰과 조직계측학적 분석을 하였으며 주사전자현미경으로 임플란트의 표면 특성과 골-임플란트 계면을 관찰하였다. 결과: 페리오테스트를 이용한 임플란트 안정성 분석 결과, 대조군과 실험군 사이에 유의한 차이가 없었고, 조직학적 분석 결과, 각 군 모두 4주에 이식골의 재흡수와 조골세포의 활발한 활동에 의해 신생골이 형성되기 시작하였다. 골-임플란트 접촉률 분석 결과, 대조군과 실험군 사이에 유의한 차이가 있었으며(P<.05), 특히 4주와 12주에서 실험군과 대조군 사이에 2시점에서 유의한 차이를 보였다(P<.05). 골 면적률 분석 결과, 대조군과 실험군 사이에 유의한 차이가 없었다. 주사전자현미경 관찰 결과, 대조군은 균일한 다공성의 거친 표면을 나타냈고 실험군은 무정형 입자들이 불규칙하게 산재된 표면을 보여 주었다. 각 군 모두 4주에 임플란트 표면과 골 조직 사이에 빈 공간이 관찰되었고 12주에는 일부 공간에서 골 조직으로 채워진 양상을 보였다. 결론: 차폐막을 이용한 이종골 이식을 동반하는 경우 본 실험에 사용된 지르코니아 임플란트의 골-임플란트 접촉률은 양극산화 표면처리를 한 타이타늄 임플란트에 크게 미치지 못하므로 지르코니아 임플란트의 실용화를 위해서는 표면 처리 방법 등에 대한 지속적인 연구를 통한 개선이 필요하다고 사료된다.

• 대한치과보철학회지
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• 제43권4호
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• pp.528-543
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• 2005

Statement of problem: Repeated delivery and removal of abutment cause some changes such as wear, scratch or defect of hexagonal structure. It may increase the value of rotational freedom(RF) between hexagonal structures. Purpose: The purpose of this study was to evaluate surface changes and rotational freedom between the external hexagon of the implant fixture and internal hexagon of abutment after repeated delivery and removal under SEM and toolmaker's microscope. Materials and methods: Implant systems used for this study were 3i and Avana. Seven pail's of implant fixture, abutment and abutment screws for each system were selected and all fixtures were perpendicularly mounted in liquid unsaturated polyesther with dental surveyor. Each one was embedded beneath the platform of fixture. Surfaces of hexagonal structure before repeated closing and opening of abutment were observed using SEM and rotational freedom was measured by using toolmaker's microscope. Each abutment was secured to the implant future by each abutment screw with recommended torque value using a digital torque controller and was repeatedly delivered and removed by 20 times respectively. After experiment, evaluation for the change of hexagonal structures and measurement of rotational freedom were performed. Result : The results were as follows; 1. Wear of contact area between implant fixture and abutment was considerable in both 3i and Avana system. Scratches and defects were frequently observed at the line-angle of hexagonal structures of implant fixture and abutment. 2. In the SEM view of the external hexagon of implant fixture, the point-angle areas at the corner edge of hexagon were severely worn out in both systems. It was more notable in the case of 3i systems than in that of Avana systems. 3. In the SEM view of the internal hexagon of abutment, Gingi-Hue abutment of 3i systems showed severe wear in micro-stop contacts that were machined into the corners to prevent rotation and cemented abutment of Avana systems showed wear in both surface area adjacent to the corner mating with external hexagon of implant fixture. 4 The mean values of rotational freedom between the external hexagon of the implant fixture and internal hexagon of abutment were 0.48$\pm$0.04$^{\circ}$ in pre-tested 3i systems and 1.18$\pm$0.25$^{\circ}$ after test, and 1.80$\pm$0.04$^{\circ}$ in pre-tested Avana systems and 2.61$\pm$0.16$^{\circ}$ after test. 5. Changes of rotational freedom after test shouted statistical)y a significant increase in both 3i and Avana systems(P<0.05, paired t-test). 6. Statistically, there was no significant difference between amount of increase in the rotational freedom of 3i systems and amount of increase in that of Avana ones(P>0.05, unpaired t-test). Conclusion: Conclusively, it was considered that repeated delivery and remove of abutment by 20 times would not have influence on screw joint stability. However, it caused statistically the significant change of rotational freedom in tested systems. Therefore, it is suggested that repeated delivery and remove of abutment should be minimal as possible as it could be and be done carefully Additionally, it is suggested that the means or treatment to prevent the wear of mating components should be devised.

• 열처리공학회지
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• 제7권4호
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• pp.307-317
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• 1994

The surf ace microstructure modification by $N^+$ ion implantation into 7050Al alloy and its low cycle fatigue behavior were investigated. Ion implantation method is to physically implant accelerated ions to the surface of a substrate. High dose of nitrogen($5{\times}10^{17}ions/cm^2$) were implanted into 7050Al alloy using current density of accellerating voltage of 100KeV. The implanted layers were characterized by Electron Probe-Micro Analysis(EPMA), Auger Elecron Spectroscopy(AES), X-Ray Diffraction(XRD), X-Ray Photoelectron Spectroscopy(XPS), and Transmission Electron Microscopy(TEM). The experimental results were compared with computer simulation data. It was shown that AlN was formed to 4500 ${\AA}$ deep. The low cycle fatigue life of the $N^4$ion modified material was prolonged by about three times the unimplanted one. The improved low cycle fatigue life was attributed to the formation of AlN and the damaged region on the surface by $N^+$ ion implantation.

• Journal of Periodontal and Implant Science
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• 제24권1호
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• pp.109-119
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• 1994

An essential fact in the regeneration of new periodontal tissue after periodontal therapy is the reattachment of collagen fibers to the tooth. Two phenomena play a fundamental role in preventing new connective tissue attachment to the exposed root surface ; 1) The apical migration of the junctional epithelium 2) The contamination of cementum by toxic substances, especially endotoxins. Authors have used rat submucosal implantation of root sections to study the connective tissue healing to periodontally diseaed root, previously planed and demineralized with citric acid and tetracycline- HCl. The results were obtained as follows. 1. The connective tissue attachment was increased in tetracycline, citric acid, non disease, scaling and root planing order and inflammatory reaction was seen in the rat teeth, no treatment group. 2. Collagen fiber attachment at the dentin surface was more increased than cementum surface 3. In 2 week of citric acid and tetracycline-HCl specimens, osteoid was seen near the fibrotic band. 4. In the MT view, collagen fiber formation was increased with time and the numerous collagen fiber and connective tissue was more densly attached to the tooth surfaces in the tetracycline-HCl group than the citric acid group.

• 대한치과의사협회지
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• 제48권2호
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• pp.106-112
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• 2010

아직까지 나노관련 기술이 티타늄 임플란트에 직접적으로 사용되는 부분이 상당히 미약하다. 하지만, 수직으로 정렬된 구조를 가지는 티타니아 나노튜브는 생체 내 대부분의 임플란트 재료로 사용되는 티타늄의 차세대 개발에 있어서 가장 중요한 영향을 미칠 것이다. 본문에 설명되어 있는 내용들 뿐 만이라, 티타니아 나노튜브는 파골세포의 골 흡수성 방지, 줄기세포의 특정 성체세포로의 분화, 연골세포의 재분화, 간세포를 이용한 생물 반응기(bio-reactor) 개발 등 생체재료의 여러 분야에서 많이 연구되고 있다. 특히, 줄기세포에 관한 연구는 차세대 임플란트 개발에 있어서 가장 중요한 연구 분야 중의 하나로서, 골을 형성하는 조골세포와 골을 파괴하는 피골세포 모두 줄기세포 로부터 만들어진다는 것을 유념해야 할 것이다. 만약, 티타니아 나노튜브의 독특한 나노구조를 이용하여 줄기세포의 조골세포로의 직접 분회를 제어하는 기술이 개발되어 상업화된다면, 이 기술을 기반으로 하여 현 재까지 개발된 모든 표면 증착 및 코팅 기술을 새롭게 이용하는 차세대 티타늄 임플란트의 개발을 위한 초석이 되리라고 본다.

• Journal of Korean Dental Science
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• 제10권1호
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• pp.10-21
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• 2017

Purpose: The purpose of this study was to investigate the electrochemical characteristics of nanotubular Ti-25Nb-xZr ternary alloys for dental implant materials. Materials and Methods: Ti-25Nb-xZr alloys with different Zr contents (0, 3, 7, and 15 wt.%) were manufactured using commercially pure titanium (CP-Ti), niobium (Nb), and zirconium (Zr) (99.95 wt.% purity). The alloys were prepared by arc melting in argon (Ar) atmosphere. The Ti-25Nb-xZr alloys were homogenized in Ar atmosphere at $1,000^{\circ}C$ for 12 hours followed by quenching into ice water. The microstructure of the Ti-25Nb-xZr alloys was examined by a field emission scanning electron microscope. The phases in the alloys were identified by an X-ray diffractometer. The chemical composition of the nanotube-formed surfaces was determined by energy-dispersive X-ray spectroscopy. Self-organized $TiO_2$ was prepared by electrochemical oxidation of the samples in a $1.0M\;H_3PO_4+0.8wt.%$ NaF electrolyte. The anodization potential was 30 V and time was 1 hour by DC supplier. Surface wettability was evaluated for both the metallographically polished and nanotube-formed surfaces using a contact-angle goniometer. The corrosion properties of the specimens were investigated using a 0.9 wt.% aqueous solution of NaCl at $36^{\circ}C{\pm}5^{\circ}C$ using a potentiodynamic polarization test. Result: Needle-like structure of Ti-25Nb-xZr alloys was transform to equiaxed structure as Zr content increased. Nanotube formed on Ti-25Nb-xZr alloys show two sizes of nanotube structure. The diameters of the large tubes decreased and small tubes increased as Zr content increased. The lower contact angles for nanotube formed Ti-25NbxZr alloys surfaces showed compare to non-nanotube formed surface. The corrosion resistance of alloy increased as Zr content increased, and nanotube formed surface showed longer the passive regions compared to non-treatment surface. Conclusion: It is confirmed that corrosion resistance of alloy increased as Zr content increased, and nanotube formed surface has longer passive region compared to without treatment surface.

• Journal of Periodontal and Implant Science
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• 제43권2호
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• pp.101-105
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• 2013

Purpose: The present study aimed to measure root surface roughness in teeth with periodontitis by a profilometer following root planning with ultrasonic and hand instruments with and without erbium-doped yttrium aluminium garnet (Er:YAG) laser irradiation. Methods: Sixty single-rooted maxillary and mandibular teeth, extracted because of periodontal disease, were collected. The crowns and apices of the roots were cut off using a diamond bur and water coolant. The specimens were mounted in an acrylic resin block such that a plain root surface was accessible. After primary evaluation and setting a baseline, the samples were divided into 4 groups. In group 1, the samples were root planned using a manual curette. The group 2 samples were prepared with an ultrasonic scaler. In group 3, after scaling with hand instrumentation, the roots were treated with a Smart 1240D plus Er:YAG laser and in group 4, the roots were prepared with ultrasonic scaler and subsequently treated with an Er:YAG laser. Root surface roughness was then measured by a profilometer (MahrSurf M300+RD18C system) under controlled laboratory conditions at a temperature of $25^{\circ}C$ and 41% humidity. The data were analyzed statistically using analysis of variance and a t-test (P<0.05). Results: Significant differences were detected in terms of surface roughness and surface distortion before and after treatment. The average reduction of the surface roughness after treatment in groups 1, 2, 3, and 4 was 1.89, 1.88, 1.40, and 1.52, respectively. These findings revealed no significant differences among the four groups. Conclusions: An Er:YAG laser as an adjunct to traditional scaling and root planning reduces root surface roughness. However, the surface ultrastructure is more irregular than when using conventional methods.

• 대한치과보철학회지
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• 제39권4호
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• pp.391-409
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• 2001

Since the early study about the osseointegration, lots of researches have been performed to increase the success rate and the stress around the implant in the jaw bone has been considered as one of the causes of failure. The purpose of this study was to examine the relationship between the implant failure and the stress by analysing the influence of different bone quality and bite force of some foods on the stress distribution around the implant, and to estimate the treatment result according to the bone quality and dietary pattern of patients. Bone quality was divided in 4 groups and models were drawn with the assumption that thread type implant(Nobel Biocare AB, Goteborg, Sweden) of 3.75mm diameter, 13mm length was installed to the bones. Various bite forces were applied to the occlusal surface of superstructure and the stress distributed around the implant were analysed with finite element analysis program. The results were as follows ; 1. The stress was changed proportionally to the bite forces of foods at all measuring points in all load cases. 2. The stress at the marginal bone was higher than that of the other measuring points in all load cases, and it was decreased at the first thread area. 3. The stress at the marginal bone was highest in type IV bone in all load cases. Especially it was twice those of other bone types at the bucco-lingual marginal bone and 50% higher at the mesio-distal marginal bone. 4. The stress at the bucco-lingual sides of the bone around the apical portions of implant showed little differences among the bone types, while type IV bone showed lower stress concentration than the other bone types in the mesio-distal sides. 5. Under the buccal oblique load ($15^{\circ}$ ), the stress at the lingual marginal bone was higher than that of buccal marginal bone, and the difference between the two points was almost same regardless of bone types.

• Journal of Periodontal and Implant Science
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• 제25권3호
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• pp.614-622
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• 1995

Root caries is very frequently developed on exposed root surface after periodontal surgical treatment. In order to determine the anti-caries effect of Nd : YAG laser irradiation on periodontally exposed root surface, 40 mandibular molar teeth that had been extracted due to excessive periodontal destruction were used as the experimental teeth. All teeth were treated by the same procedure as conventional periodontal root treatment, ie thorough scaling, root planing and root conditioning with tetracycline HCl(100mg/ml, 5min.). Within middle one third of root, mesial half surface(20) or distal half surface(20) was randomly irradiated at various power of 1.0W, 2.0W, 3.0W and 4.0W for 60 seconds by non-contact(5mm) delivery of a pulsed Nd : YAG laser(EN.EL.EN060, Italy). The microhardness was measured by Vikers microhardness tester(Wilson, USA) at 2mm/second of jog speed under 100gm load. The difference of microhardness between irradiated side and non-irradiated side was statistically analyzed ANOVA and Duncan's method. Following results were obtained ; 1. The microhardness(Knoop hardness number) was significantly higher in laser irradiated surface than non-irradiated surface(p<0.05). 2. There was no significant difference in microhardness between experimental groups classified by different laser power(p>0.1). The results suggest that Nd : YAG laser irradiation on exposed root suface after periodontal therapy may inhibit the root caries development by enhancing surface microhardness.

• 대한치과보철학회지
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• 제53권1호
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• pp.9-18
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• 2015

목적: 본 연구는 Tricalcium phosphate 입자를 사용한 모재분사 후 양극산화처리를 한 임플란트 표면의 특성을 분석하고, 골모유사세포의 반응을 평가하고자 하였다. 재료 및 방법: 직경 10 mm, 두께 3.0 mm 크기의 Grade IV 타이타늄 디스크를 시편으로 사용하였으며, 양극산화처리(ASD)군, 모재 분사 후 양극산화(RBM/ASD)군, 대조군(machined surface)으로 나누어 표면처리하였다. 표면처리 후 FE-SEM, 에너지분산분광기와 주사전자현미경을 사용하여 표면특성을 평가하였다. 세포의 부착을 평가하기 위해 골모유사세포를 이용해 crystal violet assay를 통해 세포부착을 평가하고, 세포 형태는 공초점 레이저 현미경을 사용하여 관찰하였다. 세포증식을 평가하기 위해 XTT 시험을, 세포분화는 역전사 중합효소연쇄반응을 사용하였으며 침착된 칼슘의 양을 측정하기 위해 Alizarin red S stain 을 이용하였다. 비교분석은 one-way ANOVA (SPSS version 18.0)로 유의수준 5%에서 검정하였다. 결과: ASD군과 RBM/ASD군에서, 분화구 모양의 표면 형상이 나타났으며, 대조군과 비교하여 산소와 인산 이온이 관찰되었다. 단위면적당 거칠기는 대조군에서 $0.08{\pm}0.04{\mu}m$, ASD군에서 $0.52{\pm}0.14{\mu}m$, RBM/ASD군에서 $1.45{\pm}0.25{\mu}m$를 보였다. 세포반응실험에서, ASD군과 RBM/ASD군이 대조군에 비해 세포의 부착정도가 높았으며 대조군이 세포증식에서 가장 높은 값을 보였다(P<.05). RT-PCR 실험에서, RBM/ASD군이 다른 군들보다 높은 ALP를 보였다(P<.05). ASD군과 비교했을 때 RBM/ASD군은 세포부착과 증식 정도에서 큰 값을 보였다(P<.05). 결론: 본 연구의 한계내에서 모재분사 후 양극산화 처리한 티타늄 표면 처리 방식이 단순 양극산화 처리한 군이나 대조군보다 골모유사세포의 반응에 효과적인 방법임을 확인하였다.