• The Journal of Advanced Prosthodontics
• /
• v.5 no.3
• /
• pp.296-304
• /
• 2013

PURPOSE. The aim of this study was to evaluate the effect of polishing and glazing on the color and spectral distribution of monolithic zirconia. MATERIALS AND METHODS. Forty-five monolithic zirconia specimens ($16.3mm{\times}16.4mm{\times}2.0mm$) were fabricated and divided into 5 groups according to the number of A2-coloring liquid applications (Group I to V). Each group was divided into 3 subgroups according to the method of surface treatments (n=3): N: no treatment; P: polishing; G: glazing. Color and spectral distribution of five different areas of each specimen were measured according to CIELAB color space in the reflectance mode relative to the standard illuminant D65 on a reflection spectrophotometer. Data were analyzed using one-way ANOVA followed by Tukey's HSD test, Pearson correlation and regression analysis (${\alpha}$=.05). RESULTS. There was a significant difference in CIE $L^*$ between Subgroup N and P, and in CIE $b^*$ between Subgroup P and G in each group. Spectral reflectance generally decreased in Subgroup P and G in comparison with Subgroup N. Color differences between Subgroup P and G were within the perceptibility threshold (${\Delta}E{^*}_{ab}$ < 3.7) in most groups. Highly significant correlation was found between CIE $b^*$ and each subgroups as the number of coloring liquid applications increased ($R^2$ >0.88, P<.001). CONCLUSION. A perceptible color difference can be detected after polishing of monolithic zirconia. Polishing decreases the lightness, and glazing also decreases the lightness, but increases the yellowness of monolithic zirconia.

• The Journal of Advanced Prosthodontics
• /
• v.12 no.5
• /
• pp.259-264
• /
• 2020

PURPOSE. The aim of this study was to investigate and compare the color stability of provisional restorative materials fabricated by 3D printing, dental milling, and conventional materials. MATERIALS AND METHODS. For the experimental groups, two commercially available 3D-printing provisional resins (E-Dent 100; EnvisionTEC GmbH, Germany & VeroGlaze™; Stratasys^®, USA), two dental milling blocks (PMMA Disk; Yamahachi Dental Co., Japan & Telio^®CAD; Ivoclar Vivadent AG, Liechtenstein), and two conventional materials (Alike™; GC Co., Japan & Luxatemp automix plus; DMG, Germany) were used. The water sorption and solubility test were (n=10, respectively) carried out according to ISO4049:2000 (International Standards Organization, Geneva, Switzerland). For the color stability test (n=10), coffee and black tea were used as staining solutions, and the specimens were stored for 12 weeks. Data were analyzed by one-way ANOVA and Tukey's HSD using SPSS version 22.0 (SPSS Inc. Chicago, IL, USA) (P<.05). RESULTS. Alike and Veroglaze showed the highest values and Luxatemp showed the lowest water sorption. In the color stability test, the ΔE of conventional materials varied depending on the staining solution. PMMA milling blocks showed a relatively low ΔE up to 4 weeks, and then significantly increased after 8 weeks (P<.05). 3D-printed materials exhibited a high ΔE or a significant increase over time (P<.05). CONCLUSION. The degree of discoloration increased with time, and a visually perceptible color difference value (ΔE) was shown regardless of the materials and solutions. PMMA milled and 3D-printed materials showed more rapid change in discoloration after 8 weeks.

• Proceedings of the Korean Ceranic Society Conference
• /
• 2002.10a
• /
• pp.79.2-79
• /
• 2002

• Proceedings of the Korean Ceranic Society Conference
• /
• 2002.10a
• /
• pp.152.2-152
• /
• 2002

• Journal of the Korean Ceramic Society
• /
• v.32 no.10
• /
• pp.1203-1211
• /
• 1995

The tests of three point bending and vickers hardness have been carried out to investigate mechanical characteristics of bioceramics for artificial dental crowns. And color and color difference test has been performed to study chromaticity changes after sintering specimens composited with glass and leucite powders. In addition, thermal dilation test has been carried out to examine bonding relations between dental porcelain and metal frame (Ni-Cr alloy). The result of three point bending test showed a maximum strength of about 68 MPa. Thermal expansion coefficient changed from 8.3$\times$10-6/$^{\circ}C$ to 13.5$\times$10-6/$^{\circ}C$ with increasing leucite content (0~30wt.%) in glass matrix. Bonding between porcelain (25% leucite-75% glass) and Ni-Cr alloy was excellent.

• Proceedings of the KACD Conference
• /
• 2003.11a
• /
• pp.610-610
• /
• 2003

The purpose of this study was to propose a new dental color system through color evaluation of generally used dental composite and porcelain. In this study, Vita Omega 900 dental porcelain and 10 kinds of composite resins were used. A disk specimens(15mm diameter, 4mm thickness) of each material/shade combination were made. Resin compasite was condensed into Teflon mold and pressed between glass plates to flatten the surface. Pressed compasite was polymerized using an Optilux 501(Demetron, USA) for 200 seconds of each side.(중략)

• The Journal of Advanced Prosthodontics
• /
• v.8 no.1
• /
• pp.37-42
• /
• 2016

PURPOSE. This study investigated the effect of amount of thickness reduction on color and translucency of dental monolithic zirconia ceramics. MATERIALS AND METHODS. One-hundred sixty-five monolithic zirconia specimens ($16.3mm{\times}16.3mm{\times}2.0mm$) were divided into 5 groups (Group I to V) according to the number of A2-coloring liquid applications. Each group was then divided into 11 subgroups by reducing the thickness up to 1.0 mm in 0.1-mm increments (Subgroup 0 to 10, n=3). Colors and spectral distributions were measured according to CIELAB on a reflection spectrophotometer. All measurements were performed on five different areas of each specimen. Color difference (${\Delta}E^*{^_{ab}}$) and translucency parameter (TP) were calculated. Data were analyzed using one-way ANOVA and multiple comparison $Scheff{\acute{e}}$ test (${\alpha}=.05$). RESULTS. There were significant differences in CIE $L^*$ between Subgroup 0 and other subgroups in all groups. CIE $a^*$ increased (0.52<$R^2$<0.73), while CIE $b^*$ decreased (0.00<$R^2$<0.74) in all groups with increasing thickness reduction. Perceptible color differences (${\Delta}E^*{^_{ab}}$>3.7) were obtained between Subgroup 0 and other subgroups. TP values generally increased as the thickness reduction increased in all groups ($R^2$>0.89, P<.001). CONCLUSION. Increasing thickness reduction reduces lightness and increases a reddish, bluish appearance, and translucency of monolithic zirconia ceramics.

• The Journal of Korean Academy of Prosthodontics
• /
• v.38 no.1
• /
• pp.73-84
• /
• 2000

Dental porcelain should have adequate strength and similar esthetics as natural teeth. Recently esthetics has become a high priority in clinical dentistry. Thus the evaluation of color stability of dental porcelain has become an important part in dental research. The purpose of this study was to evaluate the difference in color stability of 3 types of porcelain(Vintage, VMK 95, CERAMCO II). The porcelain were divided into groups by 2 types of treatment(glazing or non-glazing and thermocycling or non-thermocycling). The porcelain were dyed with methylene blue and distilled water, and then the color stability was evaluated with a spectrophotometer The results were as follows; 1. The color change of porcelain increased in the order of VMK 95, Vintage, CERAMCO II. But there was no significant difference. 2. The color change decreased in the glazing group compared to the non-glazing group(p<0.05). 3. The color change increased after thermocycling But there was no significant difference. 4. The color change according to dye method was significantly larger with methylene blue copared to distilled water(p<0.05).

• The Journal of Advanced Prosthodontics
• /
• v.10 no.3
• /
• pp.218-226
• /
• 2018

PURPOSE. The aim of this study was to define a color space of non-vital teeth and to compare it with the color space of matched vital teeth, recorded in the same patients. MATERIALS AND METHODS. In a group of 218 patients, with the age range from 17 to 70, the middle third of the buccal surface of 359 devitalized teeth was measured using a clinical spectrophotometer (Vita Easyshade Advance). Lightness ($L^*$), chromatic parameters ($a^*$, $b^*$), chroma ($C^*$), hue angle (h) and the closest Vita shade in Classical and 3D Master codifications were recorded. For each patient, the same data were recorded in a vital reference tooth. The measurements were performed by the same operator with the same spectrophotometer, using a standardized protocol for color evaluation. RESULTS. The color coordinates of non-vital teeth varied as follows: lightness $L^*$: 52.83-92.93, $C^*$: 8.23-58.90, h: 51.20-101.53, $a^*$: -2.53-24.80, $b^*$: 8.10-53.43. For the reference vital teeth, the ranges of color parameters were: $L^*$: 60.90-97.16, $C^*$: 8.43-39.23, h: 75.30-101.13, $a^*$: -2.36-9.60, $b^*$: 8.36-39.23. The color differences between vital and non-vital teeth depended on tooth group, but not on patient age. CONCLUSION. Non-vital teeth had a wider color space than vital ones. Non-vital teeth were darker (decreased lightness), more saturated (increased chroma), and with an increased range of the hue interval. An increased tendency towards positive values on the $a^*$ and $b^*$ axes suggested redder and yellower non-vital teeth compared to vital ones.

• Journal of Technologic Dentistry
• /
• v.35 no.3
• /
• pp.185-192
• /
• 2013

Purpose: The aim of this study was to compare with color reproducibility of the coating method and dipping method using a colour liquid. Methods: Two groups of square-shaped specimens ($10mm{\times}10mm$ in diameter, 1.5mm thickness) were prepared for analysis(n=15/group). The CM(Coating Method) group was fabricated as full zirconia specimens with the coating coloring method and Group DM(Dipping Method) was prepared as specimens of 0.7 mm-thick zirconia plate using the dipping coloring method and veneered with 0.8mm-thick porcelain. Color parameters were measured with ShadeEye $NCC^{(R)}$ spectrophotometer and color differences were calculated using the equation ${\Delta}E^*= \{({\Delta}L^*)^2+({\Delta}a^*)^2+({\Delta}b^*)^2\}^{1/2}$. Non-parametric statistical methods, the Mann-Whitney test, and the Kruskal-Wallis test were used to analyze the data. Type one error rate was set at 0.05. Results: Color difference values larger than 7 were observed between specimens with the coating method and the dipping method, which were detectable difference in a clinical setting. Conclusion: Cautious application of the coating coloring method in a clinical setting and further researches to standardize the coating method are needed.