• Journal of Periodontal and Implant Science
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• 제27권3호
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• pp.621-631
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• 1997

To verify the effect of subgingival calculus on the periodontal tissues in periodontitis and the effectiveness of supragingival scaling to remove the calculus, 30 teeth from healthy group (Probing pocket depth:$PPD{\leq}mm$: HP group), 15 teeth from moderate group ($4{\leq}PD<7mm$:MP group), 30 teeth from advanced group (PPD>7mm: AP group) were selected and supragingival scaling was performed before extraction of all experimental teeth. After careful extraction, the teeth were cleaned with saline and disclosed with toluidine blue and carefully examined the relationship and distance between the calculus attached on the root surface and periodontal tissues. As a result, it was; 1. The calculus was not discovered on the root surface of teeth in HP group, but was in MP and AP group, mostly on interproximal surface and furca area. The shape of the attached calculus was ovoid, trepazoid and polygonal and the calculus was distributed randomly over the root surface. 2. PPD was more than the distance between the gingival margin to the level of attached connective tissue in AP group rather than in HP and MP group. 3. The length of calculus was $2.7mm{\pm}.44mm$ in HP group and $4.1{\pm}.89in$ AP group. 4. The distance between the apical margin of calculus and the level of attached connective tissue was $2.4{\pm}.33mm$ in MP group and $3.4{\pm}.89mm$ in AP group. 5. The length of subgingival calculus was tended to increase in relation to the probing pocket depth. Therefore, it can be concluded, the calculus in periodontal pocket can not be removed completely with supragingival scaling. As the terminal part of calculus was far away with limited distance from the periodontal tissue, it can be said that the calculus was not a direct factor in destroying the periodontal tissue. In this study, the extent of the plaque was not verified but the location of calculus can be used in clinical practice for complete removal of calculus when the distance relation bewteen calculus and plaque will be known.

• 한국표면공학회:학술대회논문집
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• 한국표면공학회 2003년도 추계학술발표회초록집
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• pp.134-135
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• 2003

The dental implant materials required good mechanical properties, such as fatigue strength, combined with a high resistance to corrosion. For increasing fatigue resistance and delaying onset of stress corrosion cracking, shot peening has been used for > 50 years to extend service life of metal components. However, there is no information on the electrochemical behavior of shot peened and hydroxyapatite(HA) coated Ti-6Al-4V alloys. To increase fatigue strength, good corrosion resistance, and biocompatibility, the electrochemical characteristics of Ti/TiN/HA coated and shot peened Ti-6Al-4V alloys by electron beam physical vapor deposition(EB-PVD) have been researched by various electrochemical method in 0.9%NaCl. Ti-6Al-4V alloys were prepared under the condition of hydrogen and vacuum arc furnace. The produced materials were quenched at 1000$^{\circ}C$ under high purity dried Ar atmosphere and were hold at 500$^{\circ}C$ for 2 hrs to achieve the fatigue strength(1140㎫) of materials. Ti-6Al-4V alloys were prepared under the condition of hydrogen and vacuum arc furnace. Shot peening(SP) and sand blasting treatment was carried out for 1, 5, and 10min. On the surface of Ti-6Al-4V alloys using the steel balls of 0.5mm and alumina sand of 40$\mu\textrm{m}$ size. Ti/TiN/HA multilayer coatings were carried out by using electron-beam deposition method(EB-PVD) as shown Fig. 1. Bulk Ti, powder TiN and hydroxyapatite were used as the source of the deposition materials. Electrons were accelerated by high voltage of 4.2kV with 80 - 120mA on the deposition materials at 350$^{\circ}C$ in 2.0 X 10-6 torr vacuum. Ti/TiN/HA multilayer coated surfaces and layers were investigated by SEM and XRD. A saturated calomel electrode as a reference electrode, and high density carbon electrode as a counter electrode, were set according to ASTM GS-87. The potentials were controlled at a scan rate of 100 mV/min. by a potentiostat (EG&G Co.273A) connected to a computer system. Electrochemical tests were used to investigate the electrochemical characteristics of Ti/TiN/HA coated and shot peened materials in 0.9% NaCl solution at 36.5$^{\circ}C$. After each electrochemical measurement, the corrosion surface of each sample was investigated by SEM.

• Journal of Periodontal and Implant Science
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• 제29권3호
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• pp.715-724
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• 1999

The purpose of this study was to approve the possibility of clinical application of selftesting technique to confirm the cleanness status of the tooth surface after mechanical toothbrushing. Thirty-two periodontal patients who did not compromise any other systemic diseases were divided into two groups. Control group was instructed only the Bass method for toothbrushing, and then experimental group was demonstrated the Bass method and self-testing technique respectively for plaque control during this experiment. Selftesting technique is composed the comparison of roughness of the labial surface of maxillary central incisor and other toothsurface with touch sense using the tip of tongue. Plaque score and Gingival index were measured as clinical parameters at baseline and 1, 2 and 4 weeks after scaling and root planing. The results were as follows ; 1. Plaque scores and gingival index of 1, 2, and 4 weeks of two groups were statistically significant differences when compared with baseline value (p<0.05). 2. Plaque scores and gingival index of baseline and 1 week between two groups were not significant differences (p<0.05). 3. Plaque scores and gingival index of 2 and 4 weeks of test group were statistically significant difference when compared with control group (p<0.05). From the above results, self-testing technique which decides necessity of additional toothbrushing when tongue tip of subjects touch the maxillary molar buccal surfaces and mandibular molar lingual surfaces nd compares with maxillary anterior labial surfaces after toothbrushing appeared to effect the motivation of subjects. This study suggests that self-testing technique for cleanness after toothbrushing should be effect on the maintenance of oral hygiene when it is applied to clinical practice.

• 대한치과보철학회지
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• 제31권1호
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• pp.101-127
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• 1993

The purpose of this study was to observe the effects of early loading on the surrounding bone tissue of the implants. 12 ITI HS implants (8 mm) were inserted on the mandible at 3 mongrel dogs. The implants were divided into two groups; the functional group was functioned with crown, and nonfunctional group was functioned without crown. After 3 and 5 months animals were sacrificed and specimens were examined using radiography, light microscopy, scanning electron microscopy. The following results were obtained. 1. On light microscopic and scanning electron microscopic examination, the difference in the amounts of bone attachment between 3 months loaded and unloaded implants were a little. Sometimes more bone attachment were observed in loaded implants. 2. Many osteoids surrounded the fibrous connective tissues indicating of bone remodeling were observed along the outer surface of the implants. 3. On clinical, radiographic, microscopic examination, epithelial downgrowths were not observed and bone attachments to the outer surface of the implants were observed in 3 months loaded and unloaded implants with good oral hygiene. 4. Epithelial downgrowths and crater-like bone resorptions were observed on 5 months loaded and unloaded implants with poor oral hygiene. 5. Many inflammatory cells in the epithelial tissue were packed in the hollow on 5 months loaded implants.

• 대한치과보철학회지
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• 제55권2호
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• pp.187-197
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• 2017

과도한 수직피개를 가진 과개교합 환자에서 안정적인 유지접촉이 없는 경우 연조직 외상, 치질 파괴, 대합치 정출의 문제가 일어날 수 있고 이는 결과적으로 교합평면의 붕괴와 기능적, 심미적 문제로 이어진다. 치아의 상실과 마모가 발생된 환자에 대한 치료계획 수립 시 올바른 교합수직고경 설정을 통해 환자의 안정적인 악간관계를 회복시켜야 한다. 본 증례는 중심위에서 극심한 면 대 면 접촉이 발생된, 편측 구치부가 상실된 과개교합 환자에게 수직고경 증가를 동반한 완전구강회복술을 시행한 증례를 보고하였다. 보철수복 공간 확보를 위해 수직고경증가를 동반한 완전구강회복술로 안정적인 교합관계와 조화로운 전방, 측방유도를 얻어 환자의 기능적, 심미적 문제를 해결할 수 있었다.

• 접착 및 계면
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• 제3권2호
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• pp.17-29
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• 2002

Micromechanical 시험법과 표면 젖음성 측정을 이용한 implant용 생분해성 복합재료의 계면물성과 미세파괴 분해 메카니즘을 연구하였다. 분해시간이 경과함에 따라서 poly(ester-amide) (PEA)와 생활성 유리섬유의 인장강도와 탄성률 그리고 신율은 점차적으로 감소하는 경향을 보인 반면, chitosan 섬유는 거의 변화가 없었다. 생활성 유리섬유와 poly-L-lactide(PLLA) 사이의 계면전단강도는 PEA나 chitosan 섬유 시스템의 경우보다 더 큰 값을 보였으나, 계면전단강도 감소 속도는 가장 빨랐고 chitosan 섬유의 경우가 가장 느린 결과를 보였다. 접착일 ($W_a$)은 생활성 유리섬유와 PLLA 사이에서 가장 높은 값을 나타냈으며, 이러한 표면 젖음성 결과는 계면전단강도 결과와 잘 일치하였다. 계면물성과 미세파괴 분해 메카니즘은 생분해성 복합재료의 성능을 조절할 수 있는 가장 중요한 요인들이다.

• Journal of Periodontal and Implant Science
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• 제48권3호
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• pp.164-173
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• 2018

Purpose: The aim of this study was to evaluate the antimicrobial effect of a newly devised toothbrush with light-emitting diodes (LEDs) on Porphyromonas gingivalis attached to sandblasted and acid-etched titanium surfaces. Methods: The study included a control group, a commercial photodynamic therapy (PDT) group, and 3 test groups (B, BL, and BLE). The disks in the PDT group were placed in methylene blue and then irradiated with a diode laser. The B disks were only brushed, the BL disks were brushed with an LED toothbrush, and the BLE disks were placed into erythrosine and then brushed with an LED toothbrush. After the different treatments, bacteria were detached from the disks and spread on selective agar. The number of viable bacteria and percentage of bacterial reduction were determined from colony counts. Scanning electron microscopy was performed to visualize bacterial alterations. Results: The number of viable bacteria in the BLE group was significantly lower than that in the other groups (P<0.05). Scanning electron microscopy showed that bacterial cell walls were intact in the control and B groups, but changed after commercial PDT and LED exposure. Conclusions: The findings suggest that an LED toothbrush with erythrosine treatment was more effective than a commercial PDT kit in reducing the number of P. gingivalis cells attached to surface-modified titanium in vitro.

• 대한치과교정학회지
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• 제47권4호
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• pp.238-247
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• 2017

Objective: The aim of this study was to compare recycled and unused orthodontic miniscrews to determine the feasibility of reuse. The comparisons included both miniscrews with machined surfaces (MS), and those with etched surfaces (ES). Methods: Retrieved MS and ES were further divided into three subgroups according to the assigned recycling procedure: group A, air-water spray; group B, mechanical cleaning; and group C, mechanical and chemical cleaning. Unused screws were used as controls. Scanning electron microscopy, energy-dispersive X-ray spectrometry, insertion time and maximum insertion torque measurements in artificial bone, and biological responses in the form of periotest values (PTV), bone-implant contact ratio (BIC), and bone volume ratio (BV) were assessed. Results: Morphological changes after recycling mainly occurred at the screw tip, and the cortical bone penetration success rate of recycled screws was lower than that of unused screws. Retrieved ES needed more thorough cleaning than retrieved MS to produce a surface composition similar to that of unused screws. There were no significant differences in PTV or BIC between recycled and unused screws, while the BV of the former was significantly lower than that of the latter (p < 0.05). Conclusions: These results indicate that reuse of recycled orthodontic miniscrews may not be feasible from the biomechanical aspect.

• Journal of Periodontal and Implant Science
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• 제25권2호
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• pp.407-417
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• 1995

In order to evaluate the effect of platelet-derived growth factor(PDGF-BB) and guided tissue regeneration(GTR) technique on the regeneration of destructed periodontal tissue,intentional through-and-through furcation defects(4mm in height) were made on both mandibular 2nd and 4th premolars of 8 adult male dogs(30-40lb). Experimental group 1 was composed of the premolars that were treated by only topical application of PDGF-BB with 0.05M acetic acid without any barrier membrane. Experimental group 2 was composed of the premolars that were treated by GTR with expanded polytetrafluoroethylene membrane(ePTFE : Gore-tex periodontal material, USA). Experimental group 3 was composed of the premolars that were treated by GTR with ePTFE after topical application of PDGFBE. Control group was composed of the premolars that were treated by coronally positioned flap operation only without use of PDGF-BB and ePTFE membrane. All ePTFE membranes were carefully removed 4 weeks after regenerative surgery, and all experimental animals were sacrificed 8 weeks after regenerative surgery. The light microscopic findings were as follows ; (1) In experimental group 1, rapid new bone formation along the-root surface with multiple ankylosis and root resorption by multinucleated giant cells, and dense connective tissue in the central portion of the furcation defects were observed. (2) In experimental group 2, it was observed that the furcation defects were filled with newly formed bone, Sharpey's fibers were embedded into new cementum on root dentin of furcation fornix area, but the central portion and the area under furcation fornix were still filled with dense connective tissue. (3) In experimental group 3, the furcation defects were regenerated with newly formed dense bone and regular periodontal ligament with Sharpey's fibers embedded into newly formed cementum and bone underneath fornix area. (4) In control group, unoccupied space, apical migration of epithelium, dense infiltration of inflammatory cells in subepithelial connective tissue in relation to heavy plaque accumulation, and root resorption by inflammatory reaction were shown, but any new cementum formation on resorbed dentin surface could not be observed. The present study demonstrated that the combined therapy of PDGF-BB and GTR could enhance the regeneration of destructed periodontal tissue.

• Journal of Periodontal and Implant Science
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• 제47권3호
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• pp.154-164
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• 2017

Purpose: Measurement of the root surface area (RSA) is important in periodontal treatment and for the evaluation of periodontal disease as a risk factor for systemic disease. The aim of this study was to measure the RSA at 6 mm below the cementoenamel junction (CEJ) using the Mimics software (Materialise, Leuven, Belgium). Methods: We obtained cone-beam computed tomography (CBCT) data from 33 patients who had visited the Department of Oral and Maxillofacial Radiology of Dankook University Dental Hospital. The patients comprised 17 men and 16 women aged from 20 to 35 years, with a mean age of 24.4 years. Only morphologically intact teeth were included in our data. Because the third molars of the maxilla and mandible have a high deformation rate and were absent in some participants, they were not included in our research material. Results: The CBCT data were reconstructed into 3-dimensional (3D) teeth models using the Mimics software, and the RSA at 6 mm below the CEJ was separated and measured using 3-Matic (Materialise). In total, 924 3D teeth models were created, and the area at 6 mm below the CEJ could be isolated in all the models. The area at 6 mm below the CEJ was measured in all teeth from the 33 patients and compared based on sex and position (maxilla vs. mandible). Conclusions: In this study, we demonstrated that it was feasible to generate 3D data and to evaluate RSA values using CBCT and the Mimics software. These results provide deeper insights into the relationship between periodontal inflammatory burden and systemic diseases.