• 보건교육건강증진학회지
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• 제21권4호
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• pp.121-135
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• 2004

This study aims to analyze the oral health status of the elderly. Study subjects were 9,340 elderly aged over 65 who took the health examination (the first) for the local insured when the National Health Insurance Corporation carried out its survey from January to December, 2002. The subjects took an oral examination and filled in the questionnaire. Major results from the analysis are as follows: 1. Analysis of Oral Health Behavior For oral health behavior, 38.2％ of total subjects had visited a dental hospital (or clinic) in the last one year in the order of the elderly of big cities (48.3％), the elderly of medium cities (43.9％), and the elderly of rural areas (29.0％)(P<0.001). Elderly men had a higher rate than elderly women, and the younger age had a higher rate(P<0.01). For experience of oral prophylaxis, 12.3％ of the total elderly had experienced it in the order of the elderly of big cities (18.8％), the elderly of medium cities (16.0％), and the elderly of rural areas (6.4％) (P<0.001). For elderly men, the younger age had a higher rate of oral prophylaxis. The number of toothbrushing in order was twice(47.5％), once (26.7％), three times (25.0％), and none (0.7％). The younger age brushed their teeth more often (P<0.001). 2. Analysis of Oral Health Status The rate of caries was 10.6％ of the elderly surveyed. By area, the elderly of rural areas had a higher rate of caries than the elderly of cities (p<0.001) and elderly men were higher than elderly women (p<0.001). By age, many elderly aged over 80 had more than two caries. For missing teeth, the elderly of rural areas had a higher rate than the elderly of cities (p<0.001) and the older age had a higher rate(p<0.001). The rate of periodontal disease was 43.2％ of the total elderly. By area, the elderly of big cities (46.2％) had a higher rate of periodontal disease than the elderly of medium cities (39.4％) and rural areas (43.6％)(p<0.001), and elderly men (46.4％) were higher than elderly women (40.2％)(p<0.001). By age, the lower age had a higher rate of peridontal disease (p<0.001). Dental abrasion was observed in 16.9％ of the total elderly. The elderly of cities (21.0％) had a higher rate than the elderly of rural areas (12.0％)(p<0.001) and elderly men (21.3％) were higher than elderly women (12.8％)(p<0.001). Also the lower age had more dental abrasion symptoms (p<0.001). For needing a denture, the rate among the elderly was 48.5％ and was higher for the elderly of rural areas(20.9％), than the elderly of big cities(7.0％) and medium cities (10.5％)(p<0.001). For the rate of denture wearing, the elderly of rural areas(41.8％) were higher than the elderly of big cities (27.7％) and medium cities (28.2％ )(p<0.001). For the relation of drinking and smoking to oral health, the elderly who had a higher frequency of drinking, had a higher rate of caries (p<0.001)periodontal disease(p<0.001) and missing teeth(p<0.001) Smokers had a higher rate of caries (p<0.001), periodontal disease (p<0.05), and missing teeth (p<0.001) than nonsmokers.

• 한국기계가공학회지
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• 제14권2호
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• pp.19-24
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• 2015

Gears are produced through a variety of methods. In general, a metal piece is formed into the general shape of a gear through rough cuts. The gear then moves on to a more precise machine that removes more material. Grinders work via abrasion, rubbing a rough surface against a work piece at such high speeds that it literally scrapes unwanted material away from the item. Since the grinder is spinning so fast, the material is removed very quickly. This allows a grinder to remove a very small amount without taking any unwanted material with it. This study investigates the effect of grinding process parameters like grinding spindle speed and table transfer speed on the gear grade and grinding efficiency.

• Journal of Periodontal and Implant Science
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• 제39권4호
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• pp.437-441
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• 2009

Purpose: The purpose of this report is to show three cases treated by an intergrated periodontal and restorative dentistry approach. Methods: Three patients with Miller Class Ⅰgingiva recessions associated with cervical lesions were enrolled for treatment. Two patients received a connective tissue graft and resin modified glass ionomer, and one patient was treated with a connective tissue graft, resin restoration. Keratinized gingiva and relative gingival recession were measured. Results: The mean reduction of relative gingival recession was 3.7 mm, and the mean keratinized gingiva increase was 2.5 mm. The percentage of root coverage was 80% in average. No signs of gingival inflammation or bleeding on probing were seen. The patients were satisfied with the final esthetics and had no more dentin hypersensitivity. Conclusions: This report indicates that teeth with Miller ClassⅠ gingival recession associated with cervical lesions can be successfully treated by a connective tissue graft combined with restorative dentistry. However, longitudinal randomized controlled clinical trials must be performed to support this approach.

• Restorative Dentistry and Endodontics
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• 제12권2호
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• pp.55-63
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• 1987

The purpose of this study is to evaluate the effect of dentin bonding agents on marginal leakage. V-shaped cavities were prepared on the faciocervical area of 140 extracted human teeth. In Groups of twenty cavities, they were restored as follow: Group 1 with enamel bonding resin and Silux, Group 2 Scotchbond and Silux, Group 3 enamel bonding resin and Heliomolar, Group 4 Dentin Adhesit and Heliomolar, Group 5 enamel bonding resin and Durafill, Group 6 Dentin Adhesive and Durafill, Group 7 Chembond. All specimens were thermocycled alternatively at $4^{\circ}C$ and $60^{\circ}C$ of 2% methylene blue dye solution, and sectioned faciolingually with diamond disk under water spray. The sectioned specimens observed with stereo microscope. Following results were obtained: 1. The groups filled with Scotchbond-Silux or Dentin Adhesit-Heliomolar had appeared lesser marginal leakage compared with the groups with enamel bonding resin-Silux or enamel bonding resin-Helimolar. 2. The group filled with Dentin Adhesive-Durafill did not show the reduction of the marginal leakage compared with the group with enamel bonding resin-Durafill. 3. There was significant difference among the four dentin bonding agents. Scotchbond showed the greatest marginal sealing ability, and Dentin Adhesit was the next. The marginal sealing ability of Dentin Adhesive was the worst.

• The Journal of Advanced Prosthodontics
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• 제11권1호
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• pp.7-15
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• 2019

PURPOSE. The aim of this study was to identify the effects of three aesthetic restorative materials on the wear between tooth and restoration by a pin-on-disk manner. MATERIALS AND METHODS. Six aesthetic restorative materials were used to prepare disk specimens for wear test, which were Lava Zirconia as zirconia group, Vintage MP and Cerabien ZR as veneering porcelain group, Gradia Direct microhybrid composite containing prepolymerized fillers, Filtek Z250 microhybrid composite containing zirconia glass and colloidal silica particles, and Filtek Z350 nanocomposite as composite resin group. Vertical loss of the worn cusp, change of the surface roughness of the restoration materials, and the surface topography were investigated after wear test under 9.8-N contact load. RESULTS. The porcelain groups (Vintage MP and Cerabien ZR) caused the largest vertical loss of teeth when compared with those of the composite resin and zirconia groups, and Filtek Z250 microhybrid composite results in the second-largest vertical loss of teeth. The surface of Filtek Z350 nanocomposite was deeply worn out, but visible wear on the surface of the zirconia and Gradia Direct microhybrid composite was not observed. When the zirconia surface was roughened by sand-blasting, vertical loss of teeth considerably increased when compared with that in the case of fine polished zirconia. CONCLUSION. It was identified that microhybrid composite resin containing a prepolymerized filler and zirconia with reduced surface roughness by polishing were the most desirable restorative materials among the tested materials to prevent the two-body wear between aesthetic restorative material and tooth.

• Restorative Dentistry and Endodontics
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• 제30권1호
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• pp.22-30
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• 2005

수복물의 변연 미세 누출과 마모 개선을 위해 표면 전색제가 개발되었으며 이의 효과에 대해 알아보기 위해, 규격화된 치경부 5급 와동을 25개의 소구치의 협면에 형성하고 Single Bond와 Z-250으로 수복한 뒤, $37^{\circ}C$의 증류수에 7일간 보관한 후 무작위로 5군으로 나누고 다음과 같은 재료로 제조사의 지시에 따라 표면 처리하였다 : No sealing ; Single Bond Adhesive ; Biscover ; Fortify ; Optiguard. 그 후 잇솔질 마모시험을 시행하였다. 표면 조도는 잇솔질 전후에 profilometer로 측정되었고 paired t-test와 ANOVA로 비교하였다. 접착면과 표면변화는 전자현미경으로 관찰하였다. 미세누출 평가를 위해 시편은 $2\%$ methylene blue 용액으로 염색한 뒤, 협설로 잘라 제작하였다. 입체현미경을 이용하여 교합면쪽과 치경부쪽 계면에서 미세누출을 관찰하고 Kruskal-Wallis와 Mann-Whitney U test를 이용하여 그 결과를 비교하였다. 표면 조도는 잇솔질 후 수치가 증가하였으나 통계학적으로 유의한 차이를 나타내지는 않았다. 전자 현미경 관찰 결과, 표면 전색제가 접착면에 부분적으로 남아있기도 하였으나 많은 부분에서 떨어져 나간 상태였다. 특히, 미세 틈새가 치경부쪽 변연에서 나타났다. 미세누출 실험에서는 법랑질에서 더 봉쇄효과가 좋았으며 교합면쪽 변연에서 군간에 유의할만한 차이를 나타내었다. 조절군과 Single Bond를 도포한 군에서는 치경부쪽 변연보다 법랑질쪽 변연에서 유의하게 좋은 변연 봉쇄 효과를 나타내었다.

• The Journal of Advanced Prosthodontics
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• 제5권2호
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• pp.126-132
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• 2013

PURPOSE. Post surface conditioning is necessary to expose the glass fibers to enable bonding between fiber post and resin cement. The purpose of the present study was to evaluate the effect of different surface conditioning on tensile bond strength (TBS) of a glass fiber reinforced post to resin cement. MATERIALS AND METHODS. In this in vitro study, 40 extracted single canal central incisors were endodontically treated and post spaces were prepared. The teeth were divided into four groups according to the methods of post surface treatment (n=10): 1) Silanization after etching with 20% $H_2O_2$, 2) Silanization after airborne-particle abrasion, 3) Silanization, and 4) No conditioning (Control). Adhesive resin cement (Panavia F 2.0) was used for cementation of the fiber posts to the root canal dentin. Three slices of 3 mm thick were obtained from each root. A universal testing machine was used with a cross-head speed of 1 mm/minute for performing the push-out tests. Two-way ANOVA and Tukey post hoc tests were used for analyzing data (${\alpha}$=0.05). RESULTS. It is revealed that different surface treatments and root dentin regions had significant effects on TBS, but the interaction between surface treatments and root canal regions had no significant effect on TBS. There was significant difference among $H_2O_2$ + Silane Group and other three groups. CONCLUSION. There were significant differences among the mean TBS values of different surface treatments. Application of hydrogen peroxide before silanization increased the bond strength between resin cements and fiber posts. The mean TBS mean values was significantly greater in the coronal region of root canal than the middle and apical thirds.

• 대한치과보철학회지
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• 제57권3호
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• pp.280-287
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• 2019

구강이라는 특수한 환경 속에서 치아는 평생을 거쳐 마모, 부식 등을 겪게 된다. 점진적이며 일정한 치아의 마모는 노화의 자연스러운 현상이나, 특정 요소에 의한 마모나 부식 등은 병적인 요소이며 교합면의 병리적 손상과 이에 따른 교합 부조화, 심미적 문제, 턱관절 장애 등을 야기할 수 있다. 본 증례는 26세의 젊은 여성 환자로 전반적인 치아의 마모와 부식이 동반된 상태였다. 디지털 안모 분석, 생리적 안정위, 전치부 치관 길이 평가 등을 통해 진단 납형을 제작하였다. 디지털 분석을 통해 치관연장술에 필요한 가이드를 제작하여 수술을 진행하였고 임시 보철물을 통하여 저작 기능 및 심미성을 회복하였다. 지르코니아 최종 보철로 수복하여 심미적, 기능적으로 만족할만한 결과를 얻었으므로 이 증례를 보고하고자 한다.

• Journal of Periodontal and Implant Science
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• 제52권2호
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• pp.116-126
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• 2022

Purpose: This study evaluated the efficacy of treating periodontitis using subgingival nano-hydroxyapatite powder with an air abrasion device (NHAPA) combined with scaling and root planing (SRP). Methods: A total of 28 patients with stage III periodontitis (grade B) were included in this study, although 1 was lost during follow-up and 3 used antibiotics. The patients were divided into a test group and a control group. All patients first received whole-mouth SRP using hand instruments, and a split-mouth approach was used for the second treatment. In the test group, the teeth were treated with NHAPA for 15 seconds at 70% power per pocket. Subgingival plaque samples were obtained from the 2 deepest pockets at the test and control sites before treatment (baseline) and 3 months after treatment. The full-mouth plaque index (PI), gingival index (GI), papillary bleeding index (PBI), bleeding on probing (BOP), probing depth (PD) and clinical attachment level (CAL) were recorded at baseline and at 1- and 3-month post-treatment. Real-time polymerase chain reaction was used to determine the colonisation of Treponema denticola (Td), Porphyromonas gingivalis (Pg), and Aggregatibacter actinomycetemcomitans in the subgingival plaque. Results: From baseline to the first month, the test group showed significantly larger changes in BOP and CAL (43.705%±27.495% and 1.160±0.747 mm, respectively) than the control group (36.311%±27.599% and 0.947±0.635 mm, respectively). Periodontal parameters had improved in both groups at 3 months. The reductions of PI, GI, BOP, PD, and CAL in the test group at 3 months were greater and statistically significant. The total bacterial count and Td and Pg species had decreased significantly by the third month in both groups (P<0.05). Conclusions: Applying NHAPA in addition to SRP improves clinical periodontal parameters more than SRP alone. Subgingival NHAPA may encourage clot adhesion to tooth surfaces by increasing surface wettability.

• 한국재료학회지
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• 제33권8호
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• pp.337-343
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• 2023

3Y-TZP (3 mol% yttria-stabilized tetragonal zirconia polycrystals) ceramics have excellent mechanical properties including high fracture toughness, good abrasion resistance as well as chemical and biological stability. As a result, they are widely used in mechanical and medical components such as bearings, grinding balls, and hip implants. In addition, they provide excellent light transmittance, biocompatibility, and can match tooth color when used as a dental implant. Recently, given the materials' resemblance to human teeth, these ceramics have emerged as an alternative to titanium implants. Since the introduction of CAD/CAM in the manufacture of ceramic implants, they've been increasingly used for prosthetic restoration where aesthetics and strength are required. In this study, to improve the surface roughness of zirconia implants, we modified the 3Y-TZP surface with a biocomposite of hydroxyapatite and forsterite using room temperature spray coating methods, and investigated the mixed effect of the two powders on the evolution of surface microstructure, i.e., coating thickness and roughness, and biological interaction during the in vitro test in SBF solution. We compared improvement in bioactivity by observing dissolution and re-precipitation on the specimen surface. From the results of in vitro testing in SBF solution, we confirmed improvement in the bioactivity of the 3Y-TZP substrate after surface modification with a biocomposite of hydroxyapatite and forsterite. Surface dissolution of the coating layer and the precipitation of new hydroxyapatite particles was observed on the modified surface, indicating the improvement in bioactivity of the zirconia substrate.