• The Journal of Advanced Prosthodontics
• /
• 제11권4호
• /
• pp.215-222
• /
• 2019

PURPOSE. To evaluate the polishing effect on roughness and color change of pressed and layering ceramics after immersion in coffee solution. MATERIALS AND METHODS. 88 ceramic discs ($1.0mm{\times}10.0mm$) were manufactured - 44 nano-fluorapatite layering ceramics (IPS e.max Ceram. Group C) and 44 pressed lithium disilicate ceramic discs (IPS e. max Press - Group P). Each group was divided into 4 subgroups according to surface treatments: (G) Glaze, (S) Shofu polishing system (Shofu Inc.), (E) Edenta AG polishing System, (KG) $30-{\mu}m$ diamond granulation tip. Surface roughness (Ra) and color change (${\Delta}E$) measurings after the surface treatments were performed, before and 12 days after the immersion in coffee solution. A samples' qualitative analysis was conducted with a scanning electron microscopy (SEM). Data were statistically-treated with one-way-ANOVA and Duncan's tests, apart from paired t-test and Pearson's correlation test (${\alpha}=5%$). RESULTS. The decrescent order, both for surface roughness (Ra) and ${\Delta}E$ for both ceramics were: KG > E > S > G (P<.05). With exception for PG and CG subgroups, which did not present statistical difference between them, all other pressed ceramics subgroups presented smaller Ra values and greater ${\Delta}E$ values than the layering ceramics subgroups (P<.05). CONCLUSION. Although mechanical polishing systems presented intermediate Ra values, their colors were considered clinically acceptable. There is a strong correlation between the surface roughness and the color change of tested ceramics.

• 대한치과보철학회지
• /
• 제41권1호
• /
• pp.71-80
• /
• 2003

Development of new ceramic and esthetic need of patient increased the use of ceramic restorations. The purpose of this study was to confirm the possibility of recycling for IPS Empress2 which has a lot of advantages in esthetics. 1st, 2nd and 3rd pressed disc-shaped($10{\times}1.5mm$) IPS Empress 2 specimens were made with IPS Empress ingot(shade 200, Ivoclar, Liechtenstein) and pressing furnace(IPS Empress EP 500, Ivoclar, Liechtenstein). Flexure strength was measured with universal testing machine(Zwick 145641, Zwick, Germany), and color change and staining resistance of specimens were evaluated with colorimeter (Model TC-6FX, Tokyo Denshoku Co., Japan). The followings were drawn from this study : 1. Flexure strength of the 1st, the 2nd, and the 3rd pressed specimens showed 236.78 MPa. 247.16MPa, and 220.72MPa, respectively. Flexure strength of the 2nd pressed specimens was higher than others, but there's no statistical difference between them. 2. The color difference between the 1st and the 2nd pressed specimens was 3.25, and that between the 1st and the 3rd pressed specimens was 3.63(P<0.05). 3. The color change after staining of the 1st, the 2nd. and the 3rd pressed specimens were 1.43, 2.64, and 1.45, respectively. In this study, reused IPS Empress 2 specimens showed insignificant change of flexure strength and stain resistance, but they showed some color change according to reuse. From this results, the limited possibility of reuse for IPS Empress 2 could be considered.

• 대한치과기공학회지
• /
• 제4권1호
• /
• pp.5-7
• /
• 1982

This study was performed to examine the effect of repeated firing on porcelain color stability. Sixty sepcimens of generally uniform size and shape(9.7 12mm)were prepared using the manufactorer's specifications and among them 50 specimens that showed no defect after firing procedure were selected. All samples, abraded with sandpaper disc, ultrasonically cleaned, and air fired to amedium glaze were devided into 10 groups according to the number of repeated firing and, upon completion, mounted on a 13 by 16cm board. 30 persons(five dentists, ten dental techanicians, and fiftheen students) were asked to compare the samples for variations, in hue, chroma and value under natural and artificial light. The results were as follows:(1) There were no color change detected in the first four firings.(2) Slight color change were noticed in subsequent firings(ie: greater decreases in value with slight increases In chroam)(3) However, the hue remained constant in all 10 groups after repeated firings.

• 치위생과학회지
• /
• 제12권2호
• /
• pp.123-129
• /
• 2012

이 연구에서는 지르코니아 코어의 두께를 달리 제작하여 동일한 색조의 상부도재를 축성함에 있어 제작방법을 다르게 하여 두 상반된 시편을 각각 분광측색장치를 이용하여 CIE $L^*,a^*,b^*$ 색체계로 산출하여 객관적으로 색차를 비교, 분석하여 다음과 같은 결론을 얻었다. 1. 지르코니아 코어의 두께가 두꺼워 지고 상부도재의 두께가 얇아지면서 $L^*$ 값의 수치는 높아지며 $a^*,b^*$ 값은 낮아지는 경향을 띠었다. 상부도재 축성방법을 다르게 제작한 시편에서도 같은 결과를 보였다. 동일한 색조 시편에서 HP군은 PST군에 비해 $L^*$ 값의 수치는 낮게 측색되어 어두운 경향을 보였으며 $a^*,b^*$ 값도 낮은 수치를 보여 황색의 경향을 띠었다. 2. HP군, PST군 모두 동일한 색조에서 지르코니아 코어 두께와 상부도재 제작방법 간에 교호작용은 없었다(P=.083). 지르코니아 코어의 두께에 따라서는 통계적으로 유의한 차이는 존재하였으며(P=.001), 두께가 0.3 mm의 시편 A1, A2 색조에서 색차 값($E^*$)은 3.7 이상으로 나타났고, 그 이외 시편에서는 3.7 이하로 분석되어 임상가능 허용치로 나타났다. 이상의 결과로 볼 때 지르코니아를 이용한 전부 도재관 제작 시 같은 색조의 재료 일지라도 제작방식과 상부도재의 재료에 따라 색차 값이 존재하므로 이를 감안하여 보철물 제작에 사용해야 할 것으로 사료되며, 특히 코어의 두께가 얇은 보철물에서는 임상 허용치 이상의 색차 값을 보이므로 코어의 두께를 좀 더 추가하여 설계한 보철물이 바람직하다고 생각된다.

• 대한소아치과학회지
• /
• 제26권1호
• /
• pp.14-24
• /
• 1999

The purpose of study was to develop new dental plaque disclosants which could replace erythrosine. Three food coloring agents(Red No.40, Blue No.1, and Mixed Green), erythrosine and fluorescein were tested for their color difference, antibacterial property, and biocompatibility. Color difference of Red No.40 was greater than that of erythrosine as concentration of solution increased. Color differences of Blue No.1 and Mixed Green were smaller than that of red dyes. Erythrosine showed obvious antibacterial property, but food coloring agents showed almost no antibacterial property. The taste and sensation of erythrosine was the worst, and the taste of Red No.40 and the sensation of Mixed Green were the most tolerable. Erythrosine stained dental plaque and oral soft tissue most deeply and long, and Blue No.1 was the next in the depth and longevity of stain.

• 한국세라믹학회지
• /
• 제55권2호
• /
• pp.116-125
• /
• 2018

Color shade variation was investigated in zirconia dental blocks, prepared using commercial powders. As a reference color-shade block we used the color indexes of A2, A3.5, A4 and B3, according to the VITA classical color scale. The zirconia powders for color shade blocks showed colors of white, yellow, pink and grey, respectively, after firing at $1530^{\circ}C$. The zirconia powders were mixed according to the recipe of color shade blocks and shaped at lower pressure using a uniaxial hydrostatic press. The shaped sample was inserted into a vinyl pack and sealed in a vacuum form machine. The shaped block samples were reshaped at 450 bar using an isostatic cold press and fired at $1530^{\circ}C$ for three hours. In order to investigate the atmospheric color variation with firing temperature, the A2, A3.5, A4 and B3 sintered blocks were fired between $700^{\circ}C$ and $1300^{\circ}C$ under controlled atmosphere of $pN_2$ and $pO_2$. The surface color picture was taken using a smart phone camera and compared with the results obtained using the VITA classical color scale. Quantitative color index value, CIELAB, was measured using a color-meter. Above $800^{\circ}C$, the color darkness greatly increased with the increase of the reduction temperature and keeping time.

• 대한치과보철학회지
• /
• 제47권3호
• /
• pp.348-355
• /
• 2009

연구 목적: ShadeEye-Ncc dental chroma meter (Shofu Inc., Kyoto, Japan)와 Shadepilot$^{TM}$ system (Degudent Inc., Hanau, Germany)의 도재색조 재현의 정확성을 비교연구하여 보고자 함이다. 연구 재료 및 방법: ShadeEye-Ncc dental chroma meter와 Shadepilot$^{TM}$ system을 사용하여 Vitapan 3D Master shade guide의 2M2와 3M2 shade tap.을 측색하고, 이 자료를 통하여 shade guide tap. 형태로 도재시편을 제작한다. 시편제작 시 사용하는 porcelain system은 ShadeEye-Ncc dental chroma meter는 Vintage Halo Porcelain system을, Shadepilot$^{TM}$ system은 VitaOmega900 Porcelain system을 사용한다. 모델인 shade tap.과 제작된 도재시편을 spectrophotometer로 측색하고, 그 결과를 토대로하여 ${\Delta}E$를 계산하여, 두 측색기의 정확성을 비교검증하였다. 결과: 1. Shadepilot$^{TM}$ system이 ShadeEye-Ncc dental chroma meter에 비하여 더 적합한 도재색조 재현성을 나타내었다 (P <.05). 2. 모델인 Shade tap.의 shade에 따라서 도재색조 재현성에 차이를 나타내었다. 2M2 shade tap.에 비하여 3M2 shade tap.에서 더 적합한 도재색조 재현성을 나타내었다 (P <.05). 3. 두 측색기 모두에서 제작된 도재시편의 ${\Delta}E$가 평균4.44-6.14로 육안으로 구분 가능한 정도의 색조차이를 보였다. 결론: Shadepilot$^{TM}$ system이 비교적 더 정확한 도재색조 재현성을 나타낸다고 할 수 있으며, ShadeEye-Ncc dental chroma meter를 사용할 때는 치아 전체의 여러부분에서 측색을 하여 정확성을 높이는 것이 필요하리라 생각된다.

• 대한치과보철학회지
• /
• 제44권5호
• /
• pp.514-525
• /
• 2006

Statement of problem: The color change of final restoration resulting from resin cement is variable since the amount of the tooth is prepared is minimum. Purpose: The purpose of this study was to compare the color accuracy of try-in paste and their corresponding resin cements and the color stability of restoration intermediated resin cement according to two shades of three products(Rely-X. Variolink II. Choice). Material and method: Color was measured for porcelain disk sample without try-in paste, and porcelain disk sample intermediated by try-in paste and resin cement, then color differences were calculated. Results : 1. Color difference(${\Delta}E^*$) between try-in paste and resin cement showed the lowest value at Variolink II and increased in the order Choice and Rely-X statistically significant, and $?E^*$ of three resin cements was greater in A3 then A1. 2. The values of ${\Delta}L^*$ and ${\Delta}a^*$ between try-in paste and resin cement was in the increasing order of Variolink II, Choice and Rely-X. The ${\Delta}b^*$ value was increased in this order Choice, Rely-X and Variolink II in A1 on the other hand Variolink II, Rely-X and Choice in A3. 3. Color difference(${\Delta}E^*$) before and after resin cement showed the lowest value at Variolink II and increased in the order Rely-X and Choice. Conclusion : Above result revealed that the colors of try-in paste and resin cement were more or less accurate in the range of 0.35-1.95 of color difference which was unnoticeable with human eye, and Variolink II was superior to the other resin cements in color accuracy.

• Restorative Dentistry and Endodontics
• /
• 제46권4호
• /
• pp.51.1-51.13
• /
• 2021

Objectives: This study aimed to evaluate the effect of improper positioning single-peak and multi-peak lights on color change, microhardness of bottom and top, and surface topography of bulk fill and incremental composites after artificial aging for 1 year. Materials and Methods: Bulk fill and incremental composites were cured using multi-peak and single-peak light-emitting diode (LED) following 4 clinical conditions: (1) optimal condition (no angulation or tip displacement), (2) tip-displacement (2 mm), (3) slight tip angulation (α = 20°) and (4) moderate tip angulation (α = 35°). After 1-year of water aging, the specimens were analyzed for color changes (ΔE), Vickers hardness, surface topography (Ra, Rt, and Rv), and scanning electron microscopy. Results: For samples cured by single-peak LED, the improper positioning significantly increases the color change compared to the optimal position regardless of the type of composite (p < 0.001). For multi-peak LED, the type of resin composite and the curing condition displayed a significant effect on ΔE (p < 0.001). For both LEDs, the Vickers hardness and bottom/top ratio of Vickers hardness were affected by the type of composite and the curing condition (p < 0.01). Conclusions: The bulk fill composite presented greater resistance to wear, higher color stability, and better microhardness than the incremental composite when subjected to improper curing. The multi-peak LED improves curing under improper conditions compared to single-peak LED. Prevention of errors when curing composites requires the attention of all personnel involved in the patient's care once the clinical relevance of the appropriate polymerization reflects on reliable long-term outcomes.

• 대한치과기공학회지
• /
• 제43권3호
• /
• pp.77-83
• /
• 2021

Purpose: The purpose of this in vitro study was to measure and compare the thickness-dependent color dimensions of digital light processing (DLP) three-dimensional (3D) printer and conventional interim restorative resin. Methods: Specimens (N=60) were fabricated using either subtractive manufacturing (S group) or DLP 3D printing (D group) material. All milled and 3D-printed specimens were allocated into three different groups (n=10) according to different thicknesses as follows: 1.0, 1.5, and 2.0 mm. Color measurements in the CIELab coordinates were made using a spectrophotometer under room light conditions (1,003 lux). The color differences (𝚫E^*) between the specimen and control target data were calculated. Data were analyzed using the oneway analysis of variance (ANOVA). Post hoc comparisons were conducted using Tukey's honestly significant difference method (α=0.05 for all tests). Results: The 𝚫L^*, 𝚫a^*, 𝚫b^*, and 𝚫E^* values of interim restorative resin produced by DLP 3D printing were obtained in terms of the specimen's thickness increased compared with the increases by subtractive manufacturing. When the thickness was similar, the color difference between subtractive manufacturing and DLP 3D printing was ≥5.5, which is a value required by the dentist for remanufacturing. Conclusion: Color was influenced by the thickness of the interim restorative resin produced by DLP 3D printing.