• Composites Research
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• 제32권1호
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• pp.65-70
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• 2019

항공기 복합재료 날개 구조는 대부분 접착 혹은 패스너로 체결되어 있는데, 이러한 적층 구조 복합재료는 층간 강도가 취약하여 층간 분리가 일어나기 쉽다. 이러한 적층 복합재료의 단점을 보완하기 위해 두께 방향의 섬유를 보강한 3차원 직조형 복합재료를 통하여 강도, 손상 내구성, 충격 및 피로 하중을 향상시킬 수 있다. 또한, 자동화된 직조 공정에 의하여 단일 구조 near-net-shape의 프리폼 제조가 가능하기 때문에 공정 단축, 체결 부품 감소로 복합재료 전체 가격을 절감할 수 있다. 따라서 본 연구에서는 3차원 직조형 복합재료의 항공기 구조물 적용 가능성을 확인하기 위하여 3차원 프리폼의 기본적인 구조인 orthogonal(ORT), layer-to-layer(LTL), through-the-thickness(TTT) 패턴을 직조하고 이를 복합재료로 성형하여 압축 시험, 인장 시험, Open-hole 인장 시험을 하였다. 이 중 orthogonal 직조 복합재료가 인장 및 압축 탄성계수와 강도 모두 가장 높았으며 노치 민감도에서도 orthogonal 복합재료가 일방향 적층복합재료나 패브릭 적층 복합재료에 비하여 가장 우수한 특성을 보였다.

• 대한두개안면성형외과학회지
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• 제17권1호
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• pp.9-13
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• 2016

Background: Position of the facial foramina is important for regional block and for various maxillofacial surgical procedures. In this study, we report on anthropometry and morphology of these foramina using three-dimensional computed tomography (3D-CT) data. Methods: A retrospective review was performed for all patients who have undergone 3D-CT scan of the facial skeleton for reasons other than fracture or deformity of the facial skeleton. Anthropometry of the supraorbital, infraorbital, and mental foramina (SOF, IOF, MF) were described in relation to facial midline, inferior orbital margin, and inferior mandibular margin (FM, IOM, IMM). This data was analyzed according to sex and age. Additionally, infraorbital and mental foramen were classified into 5 positions based on the anatomic relationships to the nearest perpendicular dentition. Results: The review identified 137 patients meeting study criteria. Supraorbital foramina was more often in the shape of a foramen (62%) than that of a notch (38%). The supraorbital, infraorbital, and mental foramina were located 33.7 mm, 37.1 mm, and 33.7 mm away from the midline. The mean vertical distance between IOF and IOM was 13.4 mm. The mean distance between MF and IMM was 21.0 mm. The IOF and MF most commonly coincided with upper and lower second premolar dentition, respectively. Between the sex, the distance between MF and IMM was significantly higher for males than for female. In a correlation analysis, SOF-FM, IOF-FM and MF-FM values were significantly increased with age, but IOF-IOM values were significantly decreased with age. Conclusion: In the current study, we have reported anthropometric data concerning facial foramina in the Korean population, using a large-scale data analysis of three-dimensional computed tomography of facial skeletons. The correlations made respect to patient sex and age will provide help to operating surgeons when considering nerve blocks and periosteal dissections around the facial foramina.

• Restorative Dentistry and Endodontics
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• 제25권2호
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• pp.243-253
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• 2000

The purpose of this in vitro study was to evaluate dentin bonding by two different dentin bonding systems(DBS) using acetone based primer or adhesive [All Bond 2(AB2), One Step(OS)] when they were applied by wet or dry bonding technique. Morphology of resin-dentin interface and hybrid layer thickness(HLT) were investigated using Confocal Laser Scanning Microscope(CLSM) and compared to shear bond strength(SBS). 72 extracted sound human molars were randomly divided into 4 groups of 18 teeth each - Group 1.(AW); AB2 by wet bonding. Group 2(AD); AB2 by dry bonding. Group 3.(OW); OS by wet bonding, Group 4.(OD); OS by dry bonding. In 6 teeth of each group, notch-shaped class V cavities(depth 2mm) were prepared on buccal and lingual surface at the cementoenamel juction(12 cavities per group). To obtain color contrast in CLSM observation, bonding resins of each DBS were mixed with rhodamine B and primer of AB2 was mixed with sodium fluorescein. Prepared teeth of each group were treated with AB2, OS, respectively according to the manufacturer's instructions except for dentin surface moisture treatment after acid etching. In group 1 and 3, after acid etching, excess water was removed with wet tissue(Kimwipes), leaving consistently shiny, visibly hydrated dentin surface. In group 2 and 4, dentin surface was dried for 10 seconds at 1 inch distance. The treated teeth were then packed with composite resin(${\AE}$litefil) and light-cured. 12 microscopic samples($60{\sim}80{\mu}m$ thickness) of each group were obtained after longitudinal section and grinding(Exakt cutting and grinding system). Morphological investigation of resin-dentin interface and HLT measurement using CLSM were done. For measurement of SBS, remaining 12 teeth of each group were flattened occlusally to remove all enamel and grinded to 500 grit SiC(Pedemet Specimen Preparation Equipment). After applying DBS on the exposed dentin surface, composite resin was applied in the shape of cylinder, which has 5mm diameter, 1.5mm thickness, and light cured. SBS was measured using Instron with a crosshead speed of 0.5mm/min. It was concluded as follows, 1. HLT of AW(mean: $2.59{\mu}m$) was thicker than any other group, and followed by AD, OW, OD in descending order(mean; 2.37, 2.28, $1.92{\mu}m$). Only OD had statistically significant differences(p<0.05) to AW and AD. 2. There were intimate contact of resin and dentin at the interface in wet bonding groups, but gaps or irregular interfaces were observed in dry bonding groups. 3. The length, diameter, density of resin tags were various even in the same group without significant differences between groups and lots of adhesive lateral branches were observed. 4. There were no statistically significant difference of SBS between AB2 and OS, but SBS of wet bonding groups were significantly higher(p<0.05) than dry bonding groups. 5. There were no consistent relationships between HLT and SBS.

• 대한치과교정학회지
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• 제41권2호
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• pp.87-97
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• 2011

안면비대칭의 원인은 다양하며, 비대칭적 성장은 상악골과 하악골의 길이나 각도로 평가되어지곤 한다. 하지만 하악 과두의 비대칭적인 위치나 형태 또한 비대칭의 표현에 영향을 줄 것으로 생각된다. 따라서 본 연구는 하악 과두가 안면비대칭의 표현형인 이부 편위에 영향을 주는지에 대해 알아보고자 하였다. 50명의 골격성 III급 부정교합자 중 4 mm 이상의 menton point deviation을 보이는 비대칭군 30명, 4 mm 이하의 menton point deviation을 보이며 뚜렷한 안면비대칭이 없는 20명을 대칭군으로 하여, 두개저에 대한 좌우 하악 과두의 근원심적, 전후방적 위치를 평가하고, axial 평면에서 장축을 설정해 하악 과두의 최대 크기와 coronal plane에 대한 각도를 평가하였으며, sigmoid notch 상방 하악 과두의 길이와 부피를 측정하였다. 대칭군은 좌우 하악 과두의 위치, 각도, 크기, 길이, 부피에 있어 통계적인 차이가 없었다. 비대칭군은 이부 편위측과 비편위측으로 나누어볼 때, 이부 편위에 따른 좌우 하악 과두의 위치와 angulation 에서 통계적 차이는 없었으나, 하악 과두의 크기, 길이 및 부피에서는 비편위측 값이 컸고, 이부 편위량이 클수록 좌우 크기, 길이의 차이 및 편위측에 대한 비편위측 하악 과두의 부피비가 컸다. 또한 편위측에 대한 비편위측 하악 과두의 부피비가 이부 편위의 정도를 가장 잘 설명해주는 특성이었다. 이상의 결과를 통해 하악 과두의 비대칭이 안면비대칭의 발현에 영향을 주며, 비편위측 하악 과두가 편위측에 비해 크고 길다는 것을 알 수 있었다.

• Restorative Dentistry and Endodontics
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• 제26권4호
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• pp.332-340
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• 2001

Flowable composite resin has lower filler content, increased flow, and lower modules of elasticity. It is suggested that flowable composite resin can be bonded to the tooth structure intimately and absorb or dissipate the stress. Therefore, it may be advantageous to use flowable composite resin for the base material of class II restoration and for the class V restoraton. The purpose of this study was to evaluate the microleakage and shear bond strength of four flowable composite resins (Aeliteflo, Flow-It, Revolution, Ultraseal XT Plus) compared to Z100 using Scotchbond Multi Purpose dentin bonding system. To evaluate the microleakage, notch-shaped class V cavities were prepared on buccal and lingual surfaces of 80 extracted human premolars and molars on cementum margin. The teeth were randomly divided into non-thermocycling group (group 1) and thermocycling group (group 2) of 40 teeth each. The experimental teeth of each group were randomly divided onto five subgroups of eight samples (sixteen surfaces). The Scotchbond Multi-Purpose and composite resin were applied for each group following the manufacturer's instructions. the teeth of group 2 were thermocycled five hundred times between 5$^{\circ}C$ and 55$^{\circ}C$. The teeth of group 2 were placed in 2% methylene blue dye for 24 hours, then rinsed with tab water. The specimens were embedded in clear resin, and sectioned longitudinally with a diamond saw. The dye penetration on each of the specimen were observed with a stereomicioscope at $\times$20 magnification. To evaluate the shear bond strength, 60 teeth were divided into five groups of twelve teeth each. The experimental teeth were ground horizontally below the dentinoenamel junction, so that no enamel remained. After applying Scotchbond Multi-Purpose on the dentin surface, composite resin was applied in the shape of cylinder. The cylinder was 4mm in diameter and 2mm in thickness. Shear bond strength was measured using Instron with a cross-head speed of 0.5mm/min. After shear bond strength measurement, mode of failure was evaluated with a stereomicroscope at $\times$30 magnification. All data were statistically analyzed by One Way ANOVA and Student-Newman-Keuls method. The correlation between microleakage and shear bond strength was analyzed by linear regression. The results of this study were as follows ; 1. In non-thermocycling group, the leakage value of Z100 was significantly lower than those of flowable composite resins at the enamel and dentin margin, margin, except that Revolution showed the lower leakage value than that of Z100 at the dentin margin (p<0.05). 2. In thermocycling group, the leakage values of Z100 and Ultraseal XT Plus were lower than those of other subgroup at the enamel and dentin margin, except that Flow-It showed the lower leakage value than that of Ultraseal XT Plus at the dentin margin (p<0.05). 3. The leakage value of Z100 and Ultraseal XT Plus in thermocycling group were not higher than that in non-thermocycling group at the enamel margin. The leakage value of Z100 in thermocycling group was not higher than that in non-thermocycling group at the dentin margin (p<0.05). 4. As for the shear bond strength measurement, there were no statistically significant differences among groups (p<0.05). The shear bond strengths given in descending order were as follows: Z100(16.81$\pm$2.98 MPa), Flow-It(14.8$\pm$4.43 MPa), Aeliteflo(14.34$\pm$3.69 MPa), Revolution(13.46$\pm$4.23 MPa), Ultraseal XT Plus(12.83$\pm$3.16 MPa). 5. Failure modes of all specimens were adhesive failures. 6. There was no correlation between microleakage and shear bond strength.