• Restorative Dentistry and Endodontics
• /
• 제24권2호
• /
• pp.299-309
• /
• 1999

The composite resin, due to its esthetic qualities, is considered the material of choice for restoration of anterior teeth. With respect to shade control, the direct-placement resin composites offer some distinct advantages over indirect restorative procedures. Visible-light-cured (VLC) composites allow dentists to match existing tooth shades or to create new shades and to evaluate them immediately at the time of restoration placement. Optimal intraoral color control can be achieved if optical changes occurring during application are minimized. An ideal VLC composite, then, would be one which is optically stable throughout the polymerization process. The shade guides of the resin composites are generally made of plastic, rather than the actual composite material, and do not accurately depict the true shade, translucency, or opacity of the resin composite after polymerization. So the numerous problems associated with these shade guides lead to varied and sometimes unpredictable results. The aim of this study was to assess the color changes of current resin composite restorative materials which occur as a result of the polymerization process and to compare the color differences between the shade guides provided with the products and the actual resin composites before- and after-polymerization. The results obtained from this investigation should provide the clinician with information which may aid in improved color match of esthetic restoration. Five light activated, resin-based materials (${\AE}$litefil, Amelogen Universal, Spectrum TPH VeridonFil-Photo, and Z100) and shade guides were used in this study. Three specimens of each material and shade combination were made. Each material was condensed inside a 1.5mm thick metal mold with 10mm diameter and pressed between glass plates. Each material was measured immediately before polymerization, and polymerized with Curing Light XL 3000 (3M Dental products, USA) visible light-activation unit for 60 seconds at each side. The specimens were then polished sequentially on wet sandpaper. Shade guides were ground with polishing stones and rubber points (Shofu) to a thickness of approximately 1.5mm. Color characteristics were performed with a spectrophotometer (CM-3500d, Minolta Co., LTD). A computer-controlled spectrophotometer was used to determine CIELAB coordinates ($L^*$, $a^*$ and $b^*$) of each specimen and shade guide. The CIELAB measurements made it possible to evaluate the amount of the color difference values (${\Delta}E{^*}ab$) of resin composites before the polymerization process and shade guides using the post-polishing color of the composite as a control, CIE standard D65 was used as the light source. The results were as follows. 1. Each of the resin composites evaluated showed significant color changes during light-curing process. All the resin composites evaluated except all the tested shades of 2100 showed unacceptable level of color changes (${\Delta}E{^*}ab$ greater than 3.3) between pre-polymerization and post-polishing state. 2. Color differences between most of the resin composites tested and their corresponding shade guides were acceptable but those between C2 shade of ${\AE}$litefil and IE shade of Amelogen Universal and their respective shade guides exceeded what is acceptable. 3. Comparison of the mean ${\Delta}E{^*}ab$ values of materials revealed that Z100 showed the least overall color change between pre-polymerization and post-polishing state followed by ${\AE}$litefil, VeridonFil-Photo, Spectrum TPH, and Amelogen Universal in the order of increasing change and Amelogen Universal. Spectrum TPH, 2100, VeridonFil-Photo and ${\AE}$litefil for the color differences between actual resin and shade guide. 4. In the clinical environment, the shade guide is the better choice than the shade of the actual resin before polymerization when matching colors. But, it is recommended that custom shade guides be made from resin material itself for better color matching.

• 대한치과보철학회지
• /
• 제43권4호
• /
• pp.466-477
• /
• 2005

Statement of problem : Problem of matching the appearance of porcelain restorations with the patient's natural dentition has always been a concern to dental clinicians. Recently, demands for esthetics, even in restorations requiring strength, has brought a revolution to dentistry and increased use of zirconia. Among the various factors, shade and translucency or the core can significantly affect the overall esthetics of the restoration and should be considered when selecting an all-ceramic system. Purpose : The purpose of this study was to spectrophotometrically evaluate the influence of different zirconia systems and core thickness on the final shade of all-ceramic restorations using the CIEL$^*a^*b^*$ system. Material and Methods: Core specimens (n : 20 per group) of In-Ceram Alumina, In-Ceram Zirconia, Digident CAD/CAM Zirconia, Cercon Zirconia were fabricated 20mm in diameter. 10 specimens of each group were fabricated at core thickness of 0.5mm and 0.7mm. These core specimens were veneered with shade Al & A3 porcelain of the recommended manufacturer. CIEL$^*a^*b^*$ coordinates were recorded for each specimen with a spectrophotometer (Model CM-2600d, Minolta, Japan). Color differences were calculated using the equation ${\Delta}E^*=[({\Delta}L^*)^2+({\Delta}a^*)^2+({\Delta}b^*)^2]^{\frac{1}{2}}$. Results : 1. Specimens of core thickness 0.5mm and 0.7mm did not exhibit clinically perceived color difference. 2. Regarding shade reproducibility, In-Ceram Alumina and In-Ceram Zirconia showed significant difference within each group. 3. Cercon Zirconia group showed the highest $L^*$ value and Digident Zirconia group showed lowest $a^*$ & $b^*$ value. 4. Generally the shade difference between materials was higher in the A3 shade group than in the Al shade group. Conclusion: Within the limitations of this study, there was no color difference after increase in core thickness and every all-ceramic system has color characteristics that clinicians have to consider when selecting materials. Also, manufacturers of different porcelain systems must make every effort to achieve color reproducibility.

• Restorative Dentistry and Endodontics
• /
• 제37권2호
• /
• pp.84-89
• /
• 2012

Objectives: This study analyzed the difference in color caused by different thickness in enamel layer of composite resins when applied with single and layering placement technique, and evaluated if the results agreed with the shade guide from the manufacturers to verify reliability of the color matching process of the manufacturers. Materials and Methods: For single composite resin samples, 6 mm diameter and 4 mm thickness cylindrical samples were fabricated using Ceram-X mono (DENTSPLY DeTrey) and CIE $L^*a^*b^*$ values were measured with spectrophotometer. Same process was done for layering composite resin samples, making 3 dentinal shade samples, 4 mm thickness, for each shade using Ceram-X duo (DENTSPLY DeTrey) and enamel shade resins were layered in 2 mm thickness and CIE $L^*a^*b^*$ values were measured. These samples were ground to 0.2 mm thickness each time, and CIE $L^*a^*b^*$ values were measured to 1 mm thickness of enamel shade resin. Results: Color difference (${\Delta}E^*$) between single and layering composite resin was 1.37 minimum and 10.53 maximum when layering thicknesses were between 1 mm and 2 mm and 6 out of 10 same shade groups suggested by manufacturer showed remarkable color difference at any thickness (${\Delta}E^*$ > 3.3). Conclusion: When using Ceram-X mono and duo for composite resin restoration, following the manufacturer's instructions for choosing the shade is not appropriate, and more accurate information for Ceram-X duo is needed on the variation and expression of the shades depending on the thickness of the enamel.

• 대한소아치과학회지
• /
• 제50권1호
• /
• pp.113-120
• /
• 2023

모든 유치에 알맞은 색조의 복합레진을 수복하는 것은 소아치과 의사에게 큰 어려움이다. 최근 개발된 단일 색조 복합레진은 구조색 현상을 기반으로 주변 치질과 유사한 색상을 나타낼 수 있다. 이 연구는 단일 색조 복합레진의 유치에서의 색조 적응력(Color adjustment potential, CAP)을 일반적인 다색조 복합레진과 비교하여 평가하기 위한 연구이다. 한 개의 단일 색조 복합레진과 두 개의 다색조 복합레진이 연구에 포함되었다. Single, dual 두 종류의 표본이 제작되어 평가되었다. Single 표본은 실험군 레진을 이용하여 제2유구치 인공치를 복제하여 제작하였다. Dual 표본은 발거된 제2유구치 협면에 와동을 형성한 뒤 실험군 레진을 수복하여 제작하였다. 측색계를 이용하여 발거된 치아 및 제작된 표본의 L^*, a^*, b^* 값을 측정하였다. Single, dual 표본에 대한 ΔE_ab^* 값과 CAP 값의 평균을 계산하였으며 Bonferroni 사후 분석을 이용하여 실험군 레진 간의 통계적 유의성을 확인하였다. 실험 결과 단일 색조 복합레진이 다른 복합레진들에 비해 유의하게 큰 ΔE_Single 값을 나타내었다(p < 0.0167). 모든 실험군 레진 간 유의한 ΔE_Dual 값의 차이는 관찰되지 않았다. 단일 색조 복합레진은 다른 다색조 복합레진들과 비교 시 가장 높은 CAP 값을 나타내었다. 단일 색조 복합레진은 제2유구치에서 다른 다색조 복합레진에 비해 준수한 색조 적응력을 나타내었다. 단일 색조 복합레진은 제2유구치에서 색조 선택 과정을 단순화하면서 심미적인 수복물을 제공할 수 있을 것이다.

• 한국염색가공학회지
• /
• 제15권4호
• /
• pp.32-38
• /
• 2003

To get the variety of color by natural dyeing, cotton and silk fabrics were dyed with natural indigo and safflower in turn. The two ways of dyeing processes were carried. First, silk and cotton fabrics were dyed repeatedly in safflower dyebath to five times to get the five fabrics dyed in different shades. And then indigo dyeing process was carried on the top of the dyed fabrics with safflower. In second way, the fabrics were dyed in five stages of shade by repetition of dyeing process in indigo dyebath. And then safflower dyeing was carried on the top of the dyed fabrics with indigo. When indigo dyeing process was added on the top of the fabrics dyed in five shades with safflower, the color differences decreased between five shades of fabrics, their color values got similar in hue, shade and chroma. When safflower dyeing process was added on the top of the fabrics dyed in five shades with indigo, the fabrics showed different hue of colors between red and blue of Munsell color circle such as RP, P and PB. Like almost of fabrics dyed with plants materials, the lightfastness and laundering fastness of dyed samples were poet and drycleaning fastness were good.

• 한국지능시스템학회논문지
• /
• 제24권1호
• /
• pp.71-77
• /
• 2014

본 논문에서는 저조도 및 음영이 생기는 조명 환경하에서 성능이 개선된 계량기 숫자 인식 방법을 제안한다. 저조도 및 음영 문제를 해결하기 위해 LN(Local Normalization) 처리 기법을 이용한 조명 정규화를 수행한 후, 계량기 숫자 영역 검출과 3단계 계량기 숫자 분할이 이루어진다. 마지막으로 분할된 숫자 데이터를 분류하기 위한 하이브리드 숫자 분류기가 적용된다. 제안된 하이브리드 숫자 분류기는 역전파 신경망과 템플레이트 매칭의 연속 결합으로 이루어지고, 계량기 숫자 분류에 보다 강인한 휴리스틱 규칙에 의해 최종적으로 숫자를 분류한다. 저조도 및 음영 조명 환경하의 다양한 계량기 종류에 대해 직접 촬영하여 자체 제작한 계량기 이미지 데이터베이스에 기반한 실험을 통해 본 논문에서 제안한 숫자 인식 방법을 평가하고, 제안된 계량기 숫자 인식 방법이 효과적으로 잘 동작함을 확인하였다.

• 대한치과보철학회지
• /
• 제50권4호
• /
• pp.299-304
• /
• 2012

연구 목적: 4,000 K와 5,500 K의 색 온도를 가진 광원 하에서 치과 보철과 의사 및 치과대학 학생의 색조 비교 및 선택 능력을 평가하여 술자의 경험이 색조 선택에 영향을 주는지를 알아보고자 한다. 연구 대상 및 방법: 분광 광도계를 사용하여 색 견본을 측색한 후, 명도 값이 비슷하고 채도 값이 차이 나는 5개 탭을 선택하여 3개의 세트(a, b, c)를, 채도값이 유사하고 명도값이 차이가 나는 5개 탭을 선택하여 3개의 세트(d, e, f)를 만들었다. 각각 4,000 K, 5,500 K 색 온도의 광원 하에서 무작위로 선택된 한 개의 색 견본을 치과 보철과 의사 10명과 치과대학 학생 10명에게 제시하고 동일한 색 견본을 동일한 세트 내에서 고르게 한 다음, 제시된 색조 탭과 피험자가 선택한 색조 탭 간의 색차(${\Delta}E$) 값을 계산하여 비색 능력의 차이를 비교하였다. 광원의 색 온도 및 술자의 숙련도에 따른, 각각의 색 견본에서의 색차 값을 계산하고 95%의 신뢰 수준에서 t-test 를 시행하여 결과의 유의성을 검정하였다. 결과: 4,000K와 5,500K 광원 하에서 색차 값은 각각 $1.62{\pm}2.0$, $1.33{\pm}1.7$로 색 온도 조건에 따른 색조 선택의 차이는 나타나지 않았다(P=.398). 숙련자군과 비 숙련자군 간의 색차 값은 각각 $1.34{\pm}1.7$, $1.61{\pm}2.0$으로 각 군 간 색조 선택의 차이 또한 나타나지 않았다(P=.221). 결론: 동일한 색 견본을 동일한 광원 조건 하에서 비색하는 경우, 술자의 숙련도에 따른 색조 선택 능력에 차이가 없다.

• Restorative Dentistry and Endodontics
• /
• 제41권4호
• /
• pp.239-245
• /
• 2016

The purpose of this article was to review the changes in translucency of direct esthetic restorative materials after curing, aging and treatment. As a criterion for the evaluation of clinical translucency changes, visual perceptibility threshold in translucency parameter difference (${\Delta}TP$) of 2 was used. Translucency changes after curing were perceivable depending on experimental methods and products (largest ${\Delta}TP$ in resin composites = 15.9). Translucency changes after aging were reported as either relatively stable or showed perceivable changes by aging protocols (largest ${\Delta}TP$ in resin composites = -3.8). Translucency changes after curing, aging and treatment were perceivable in several products and experimental methods. Therefore, shade matching of direct esthetic materials should be performed considering these instabilities of translucency in direct esthetic materials.

• The Journal of Advanced Prosthodontics
• /
• 제5권3호
• /
• pp.262-269
• /
• 2013

PURPOSE. Perceived color of ceramics changes by the spectral power distribution of ambient light. This study aimed to quantify the amount of shifts in color and color coordinates of clinically simulated seven all-ceramics due to the switch of three ambient light sources using a human vision simulating spectroradiometer. MATERIALS AND METHODS. CIE color coordinates, such as $L^*$, $a^*$ and $b^*$, of ceramic specimens were measured under three light sources, which simulate the CIE standard illuminant D65 (daylight), A (incandescent lamp), and F9 (fluorescent lamp). Shifts in color and color coordinate by the switch of lights were determined. Influence of the switched light (D65 to A, or D65 to F9), shade of veneer ceramics (A2 or A3), and brand of ceramics on the shifts was analyzed by a three-way ANOVA. RESULTS. Shifts in color and color coordinates were influenced by three factors (P<.05). Color shifts by the switch to A were in the range of 5.9 to 7.7 ${\Delta}E{^*}_{ab}$ units, and those by the switch to F9 were 7.7 to 10.2; all of which were unacceptable (${\Delta}E{^*}_{ab}$ > 5.5). When switched to A, CIE $a^*$ increased (${\Delta}a^*$: 5.6 to 7.6), however, CIE $b^*$ increased (${\Delta}b^*$: 4.9 to 7.8) when switched to F9. CONCLUSION. Clinically simulated ceramics demonstrated clinically unacceptable color shifts according to the switches in ambient lights based on spectroradiometric readings. Therefore, shade matching and compatibility evaluation should be performed considering ambient lighting conditions and should be done under most relevant lighting condition.

• 한국산업융합학회 논문집
• /
• 제8권1호
• /
• pp.11-17
• /
• 2005

This study was performed to analysis the operation process when fabric pattern design was done by the use of CAD system compared with the manual work in order to determine the operation efficiency with the application of fabric design CAD system. The results of the study were as follows: 1. since 160,000 colors were supported by CAD system, color proposed by consumer was able to match exactly according to the its design. However, exact color matching was not possible by manual work. 2. Woven state of back of pattern design could be identified simultaneously with face of it for CAD system, while face and back of the fabrics should be designed separatedly in case of manual work. 3. Since the combination of warp and filling yarn was compatible with the fabric density in one repeat unit in CAD system, exact size of pattern design to be woven was able to expressed. 4. Only simple graphical expression by manual work was seen, while with the CAD system, texture and shade effect as well as graphical expression could be expressed and so fault could be reduced in advance with the simulation of actual feeling of fabrics in the screen. In conclusion, when CAD system will be introduced to the textile industry, operation time of designing pattern can be reduced. Since the operation is easy and simple, a beginner can operate CAD system easily. Thus, production and wage costs can be saved and this can be related directly with the improvement of productivity which is the main purpose of introducing CAD system.