• Restorative Dentistry and Endodontics
• /
• 제12권1호
• /
• pp.119-129
• /
• 1986

The purpose of this study was to evaluate the marginal leakage of glass ionomer cement with different cavosurface margins. 192 class V cavities were prepared on freshly extracted non-carious teeth and glass ionomer cement were inserted according to the manufacturer's instructions. Cavity preparations for this investigation were performed in four groups. The experimental specimens were made by packing the glass ionomer cement (Fuji Ionomer Type II G-C Co. Japan) into the prepared 192 cavities of four groups with different modes: Group I. - The 48 cavities with $90^{\circ}$ butt-joint cavosurface preparation and restored with glass ionomer cement. Group II. - The 48 cavities with butt-joint preparation modified by $135^{\circ}$ beveling the cavosurface in the dentin and restored with glass ionomer cement. Group III. - The 48 cavities with butt-joint preparation modified by cutting a chamfer in the dentin and restored with glass ionomer cement. Group IV. - The same 48 cavities as group I, and overfilled with glass ionomer cement beyond the cavosurface angle. And four groups above described divided into three subgroups by means of conditioning the cavity walls: Control group. - Glass ionomer cement filled in the prepared 64 cavities after being cleaned with a stream of tap water. Phosphoric acid treatment group. - Glass ionomer cement filled in the prepared 64 cavities after being conditioned with a 50% phosphoric acid. Citric acid treatment group. - Glass ionomer cement filled in the prepared 64 cavities after being conditioned with a 50% citric acid. All 192 specimens were immersed in the 2.0% basic fuchsin solution and subjected to thermal stress at one-minute intervals ($4{\pm}2^{\circ}C$ to $60{\pm}2^{\circ}C$) for 70 minutes before exposure to the dye. The specimens were sectioned ecclesiologically through the center of the restorations for different periods of immersion time, 24 hours, 7 days, 14 days 30 days. The sections were examined under a stereoscopic microscope. The results were as follows: 1. The degree of marginal leakage in group II and III was greater than that in group I and IV. 2. The degree of marginal leakage in phosphoric acid treatment group was similar with that in control group. 3. The degree of marginal leakage in citric acid treatment group was less than that in control group. 4. In all groups, the degree of marginal leakage in phosphoric acid treatment group was greater than that in citric acid treatment group. 5. There is no statistical difference of the degree of marginal leakage according to the immersion time in the dye solution.

• 대한치과보철학회지
• /
• 제26권1호
• /
• pp.51-61
• /
• 1988

The recently introduced castable glass ceramics incorporate properties characteristic of natural teeth and they are regarded as an ideal material to restore lost tooth structure. The purpose of this study was to compare the marginal fit of castable ceramic crown with that of the metal-ceramic crown in the process of heat treatment. Two master dies for castable ceramic crowns and metal-ceramic crowns were fabricated from being cast with the base metal. Each master die was duplicated with addition silicone and hard stone. Ten castable ceramic crowns were made on each hard stone die and their marginal openings were measured three times first, after casting; second, after ceramming; third, after shading. The other ten metal-ceramic crowns were made on each hard stone die and their marginal openings were measured three times : first, after casting; second, after degassing; third, after porcelain veneering. Each crown was seated on its master die with the constant force delivered by loading jig. And then, marginal openings were measured on four locations by optical projector at X50 magnification. The results were as follows: 1. The mean marginal openings of castable ceramic crowns were $31.1{\pm}12.7{\mu}m$ after casting; $44.6{\pm}12.8{\mu}m$ after ceramming; $51.2{\pm}16.8{\mu}m$ after shading. 2. The mean marginal openings of the metal-ceramic crowns were $26.2{\pm}13.8{\mu}m$ after casting; $29.8{\pm}10.3{\mu}m$ after degassing; $38.0{\pm}14.5{\mu}m$ after porcelain veneering. 3. There was significant increase in the marginal opening of castable ceramic crowns after ceramming, while metal-ceramic crowns sho(wed significant increase after porcelain veneering (p<0.05). 4. Marginal fit of metal-ceramic crown was better than that of castable ceramic crown (p<0.01).

• 한국표면공학회지
• /
• 제40권4호
• /
• pp.197-202
• /
• 2007

Fit of the restoration and its cementation procedure is crucial to both its short and long term prognosis. Marginal fit is affected by many variables during the fabrication process. These variables, being intrinsic properties of the materials or the clinical technique used, can cause changes in the size and shape of the definitive restoration. Even if all variables are controlled carefully, the seating of a restoration can still be affected due to insufficient space for the luting agent. The use of die spacer can reduce the elevation of a cast restoration of a prepared tooth, decreased seating time, improve the outflow of excess cement, and lower the seating forces. The purpose of this study was to evaluate the marginal fidelity according to die spacer application times and measurement site. Casting alloys were prepared and fabricated using non-precious metal at $950^{\circ}C$. Specimens are divided into four groups: I(die spacer painted casting for wax pattern), II(die spacer non painted casting for wax pattern). The specimens were cut and polished for marginal gap observation. The marginal gap was observed using scanning electron microscopy (SEM).

• 대한치과보철학회지
• /
• 제38권5호
• /
• pp.618-630
• /
• 2000

As Fiber-reinforced composite restorations cannot be made without leaving a marginal gap, luting cements play a pivotal role in sealing the margins as a prevention against margnal leakage. A recently introduced adhesive resin cement system is claimed to adhere chemically, as well as mechanically, to tooth substances, dental alloys and porcelain. But when considering the clinical variation conventional cementation using Zinc Phosphate and Glass-Ionomer can be requested. A vitro study was undertaken to compare microleakage and marginal fitness of Fiber-reinforced composite crowns(Targis/Vectris) depending upon luting cements. Fifty non-carious human premolar teeth were randomly divided into five experimental groups of 10 teeth each and luted with five luting cements. ($Bistite\;II^(R),\;Super-bond^(R),\;Variolink\;II^(R)$), Zinc phosphate and Glass-Ionomer cement) After 24 hours of being luted, all specimens were thermocycled 300 times through water bath of $5^{\circ}C\;and\;55^{\circ}C$ in each bath, then the quality of the marginal fitness was measured by the Digital Microscope and marginal leakage was characterized using Dye Penetration technique and the Digital Microscope The results were as follows : 1. The mean values of marginal fit were Bistite II($46.78{\mu}m$), Variolink II($56.25{\mu}m$), Super-Bond($56.78{\mu}m$), Glass-Ionomer($99.21{\mu}m$), Zinc Phosphate($109.49{\mu}m$) indicated a statistically significant difference at p<0.001. 2. The mean microleakage values of tooth-cement interface, restoration-cement interface were increased in the order of Variolink II, Bistite II, Super-Bond, Glass-Ionomer, Zinc Phosphate 3. Crowns luted with resin cement (Bistite II, Super-Bond, Variolink II, etc) exhibited less marginal gap and marginal leakage than those luted with conventional Glass-Ionomer and Zinc Phosphate cement. 4. The results indicated that all five luting systems yielded comparable and acceptable marginal fit.

• 한국동물위생학회지
• /
• 제41권4호
• /
• pp.281-285
• /
• 2018

An 11-year-old intact male mixed-breed dog was referred for evaluation of a splenic mass. On radiographs, the cardiac apex, stomach, and head of the spleen were on the right and the descending colon was on the left of the midline. In addition, the left kidney was located more cranially than the right kidney. Standard two-dimensional echocardiographic images were obtained from each inverted left and right parasternal windows. Furthermore, the spleen was observed on the right side and a splenic mass was found on the splenic tail. Based on the radiographic and ultrasonographic characteristics of the patient, a diagnosis of situs inversus totalis (SIT) and a splenic mass was made, and splenic resection was performed successfully with no unexpected complications. The splenic mass was confirmed histopathologically as being marginal zone lymphoma (MZL). This report describes a dog with SIT and splenic MZL.

• 대한치과보철학회지
• /
• 제41권1호
• /
• pp.20-34
• /
• 2003

Novel methods producing supplementary and prosthetic material by cutting or discharge processing via computer design have been proposed as alternatives for traditional casting methods and are being utilized for commercial purposes. The CAD/CAM system used in dentistry can be classified into three-dimensional input of target values, restoration design, and material processing. The marginal fidelity in production of In-Ceram core has important clinical implications and is a key consideration issue in CAD/CAM production as well. Through this research, the author arrived at the following conclusion aaer conducting comparison analysis of marginal fidelities between the In-Ceram core produced via CAD/CAM and that produced through the traditional method ; 1. In the cases of mesial, distal, and lingual margins, the core margins via CAD/CAM produced lower values than those via the traditional method, but the differences were found to be statistically insignificant. 2. In the case of labial flange, the core margins via CAD/CAM produced lower values than those via the traditional method and the differences were found to be statistically significant. (p<0.05) 3. In comparision with overall marginal fidelity, the core margins via CAD/CAM produced lower values than those via the traditional method, but the differences were found to be statistically insignificant. 4. Among the core margins produced via the traditional method did not have statistically significant differences but fir those produced via CAD/CAM had statistically significant differences between labial and lingual sides and between labial and mesial sides. (p <0.05).

• Agribusiness and Information Management
• /
• 제8권2호
• /
• pp.1-8
• /
• 2016

The present study has aimed at analyzing the technical and scale efficiencies of credit utilization by the farmer-borrowers in Chittoor district of Andhra Pradesh, India. DEA approach was followed to analyze the credit utilization efficiency and to analyze the factors influencing the credit utilization efficiency, log-linear regression analysis was attempted. DEA analysis revealed that, the number of farmers operating at CRS are more in number in marginal farms (40%) followed by other (35%) and small (17.5%) farms. Regarding the number of farmers operating at VRS, small farmers dominate the scenario with 72.5 per cent followed by other (67.5%) and marginal (42.5%) farmers. With reference to scale efficiency, marginal farmers are in majority (52.5%) followed by other (47.5%) and small (25%) farmers. At the pooled level, 26.7 per cent of the farmers are being operated at CRS, 63 per cent at VRS and 32.5 per cent of the farmers are either performed at the optimum scale or were close to the optimum scale (farms having scale efficiency values equal to or more than 0.90). Nearly 58, 15 and 28 percents of the farmers in the marginal farms category were found operating in the region of increasing, decreasing and constant returns respectively. Compared to marginal farmers category, there are less number of farmers operating at CRS both in small farmers category (15%) and other farmers category (22.5%). At the pooled level, only 5 per cent of the farmers are operating at DRS, majority of the farmers (73%) are operating at IRS and only 22 per cent of the farmers are operating at CRS indicating efficient utilization of credit. The log-linear regression model fitted to analyze the major determinants of credit utilization (technical) efficiency of farmer-borrowers revealed that, the three variables viz., cost of cultivation and family expenditure (both negatively influencing at 1% significant level) and family income (positively influencing at 1% significant level) are the major determinants of credit utilization efficiency across all the selected farmers categories and at pooled level. The analysis further indicate that, escalation in the cost of cultivation of crop enterprises in the region, rise in family expenditure and prior indebtedness of the farmers are showing adverse influence on the credit utilization efficiency of the farmer-borrowers.

• 대한전기학회:학술대회논문집
• /
• 대한전기학회 2004년도 추계학술대회 논문집 전력기술부문
• /
• pp.227-229
• /
• 2004

In a new competitive market environment, it is very important to determines how much power can be transferred through the network. It's known as Available Transfer Capability(ATC). This paper presents a technique to evaluate Reliability Assesment and the Available Transfer Capability of Haenam-Cheju HVDC transmission system using Well-being Method which is based on the probabilistic method. The system Well-being is categorized in terms of the system Healthy and Marginal in addition to the conventional Risk index. Haenam-Cheju HVDC system has been studied for the optimal ATC based in well-being categories.

• 한국해안해양공학회지
• /
• 제6권1호
• /
• pp.94-108
• /
• 1994

연근해에서의 위성고도계 자료의 정확도가 향상됨에 따라 기존에 잘 알려져 있는 Schwiderski의 전구적 모형보다 더 정확한 조석모형으로 위성고도계 자료에서의 조석성분에 대한 보정을 향상시킬 필요가 있다. 초기단계로 오오츠크해, 남중국해와 북서태평양역을 포함하는 동아시아 전 해역에 대해 기존의 조석모형보다 해상도가 높은 1/6도 격자체계의 조석모형을 수립하여 반일주조(M$_2$, S$_2$, $N_2$, $K_2$)와 일주조(K$_1$, $O_1$, P$_1$, Q$_1$)의 조석체계에 대한 수치모형실험을 수행하였다. 계산된 결과들과 이 해역에서의 관측치와 기존의 경험적 조사도 및 Schwiderski의 조석도와 비교분석이 이루어졌다.

• 자원ㆍ환경경제연구
• /
• 제33권3호
• /
• pp.203-239
• /
• 2024

지역별 차등 전기요금 제도의 도입이 논의되고 있으며, 그 방법론으로 LMP(Locational Marginal Price) 방식이 유력한 대안으로 언급되고 있다. 이런 배경하에서 본 연구는 수리모형을 통해 LMP 방식이 사회후생을 극대화하는 결과를 도출함을 제시한다. 분석 결과 사회후생 극대화 가격은 지역별 한계발전비용과 동일하며, 지역별 한계비용의 차이는 송전손실에 의해 사라지는 가치와 송전망 투자에 대한 보상을 반영한다. 그리고 송전용량이 최적 용량 미만인 경우 송전망 투자에 대한 보상액은 증분비용을 초과하여 송전망 투자의 유인이 제공된다. 반면 송전용량이 최적 용량을 초과할 경우 송전망 투자에 대한 보상액은 증분비용보다 낮아지며 용량이 상당히 큰 경우 0이 되어 투자액이 회수되지 않고 송전망 투자가 억제된다. 이는 LMP 개념하에서의 송전망 투자 보상 방식과 동일하며, 이 방식이 사회후생 극대화 및 최적 송전망 투자 시그널을 제공함을 의미한다. 이상의 분석결과는 LMP의 특성을 이해하는 데 기여하며, 추가로 본 연구에서는 LMP 개념의 도입 시 전력시장에 어떤 변화가 필요한지를 논의하였다.