Dental and composite resin discoloration induced by different hydraulic calcium silicate-based cements: two-year in vitro assessment

Abstract Few long-term studies assess the discoloration induced by hydraulic calcium silicate-based cement on dental structures. In addition, as far as we know, no long-term study has assessed the discoloration induced by these cement on composite resin. Objective This in vitro study aimed to assess, during a period of two years, the discoloration potential of different hydraulic calcium silicate-based cements (hCSCs) on the enamel/dentin structure and composite resin restoration. Methodology A total of 40 enamel/dentin discs were obtained from bovine incisors, and 40 composite resin discs (10 mm in diameter × 2 mm thick) were fabricated. A 0.8 mm-deep cavity was made in the center of each disc and filled with the following hCSCs (n=10): Original MTA (Angelus); MTA Repair HP (Angelus); NeoMTA Plus (Avalon); and Biodentine (Septodont). An initial color measurement was performed (T0 - baseline). After 7, 15, 30, 45, 90, 300 days, and two years, new color measurements were performed to determine the color (ΔE00), lightness (ΔL'), chroma (ΔC'), hue differences (ΔH'), and whiteness index (WID). Results For enamel/dentin, the ΔE00 was significant among groups and periods (p<0.05). NeoMTA Plus had the greatest ΔE00. The NeoMTA Plus group had the greatest ΔE00 after two years for composite resin. Significant reduction in lightness was observed for all groups after two years (p<0.05). The most significant WID values were observed after 30 days for Biodentine (enamel/dentin) and MTA Repair HP groups (composite resin) (p<0.05). Conclusions The hCSCs changed the colorimetric behavior of both substrates, leading to greater darkening over time. The Bi2O3 in the Original MTA seems relevant in the short periods of color change assessment.

Diagnostic value of blue light imaging-bright and linked color imaging for early esophageal cancer / 中华消化内镜杂志

Objective To investigate the diagnostic value of blue light imaging-bright (BLI-bright) and linked color imaging (LCI) for early esophageal cancer (EEC).Methods:Data of 63 consecutive patients with EEC who underwent gastroscopy under BLI-bright, LCI and white-light imaging (WLI) and endoscopic submucosal dissection (ESD) from May 2018 to August 2020 at Fuding Hospital Affiliated to Fujian University of Traditional Chinese Medicine were analyzed retrospectively in the cohort study. Subjective visibility analysis was performed by 6 endoscopists who were divided into 2 groups (expert group and trainee group) with 3 endoscopists in each group. The main observation index was the visibility score (ranking score, RS). The objective color difference (Δ E) between lesions of EEC and surrounding mucosa under 3 modes were analyzed by using the L *a *b * color space. Results:The overall RS of 6 endoscopists under WLI mode (2.57±0.81) was significantly lower than that under LCI (3.25±0.67) ( t=9.71, P<0.001) and BLI-bright (3.18±0.67) ( t=9.31, P<0.001). In the expert group, the RS of WLI (2.71±0.80) was significantly lower than that of LCI (3.33±0.66) ( t=7.16, P<0.001) and BLI-bright (3.42±0.62) ( t=8.09, P<0.001). In the trainee group, the RS of WLI (2.40±0.90) was also significantly lower than that of LCI (3.15±0.83) ( t=9.62, P<0.001) and BLI-bright (2.89±0.92) ( t=5.69, P<0.001), and the RS of LCI was higher than that of BLI-bright ( t=4.07, P<0.001). The Δ E between lesions of EEC and surrounding mucosa under WLI (11.52±3.40) was significantly lower than that under LCI (16.64±4.70) ( t=7.10, P<0.001) and BLI-bright (15.72±3.84) ( t=7.88, P<0.001). Conclusion:BLI-bright and LCI can effectively improve EEC visibility and color difference between EEC and surrounding mucosa. Furthermore, LCI is more conducive to the detection of EEC for the trainees.

Correlation Analysis between Active Ingredient Content and Color of Morus alba from Different Producing Areas Based on Color Difference Principle / 中国药房

OBJECTIVE：To stud y the correlatio n between the contents of active ingredients and the color of Morus alba ，to establish fingerprint and conduct cluster analysis of samples from different producing areas ，so as to provide reference for its quality control and evaluation. METHODS ：HPLC and HCl-Mg reaction colorimetry were used to determine the contents of morusin and total flavonoids in M. alba . The color of M. alba was observed by naked eye ，and chromaticity values （L＊，a＊，b＊） were measured by color difference meter and color aberration （E＊ab）were calculated. Pearson correlation of the contents of morusin and total flavonoids with color indicators （L＊，a＊，b＊，E＊ab）were analyzed by SPSS 21.0 software. HPLC method was used to establish the fingerprint of 20 batches of M. alba from 3 different producing areas ，and the similarity analysis was carried out. K-means cluster analysis （based on the contents of morusin and total flavonoids and corlor index ）and hierarchical cluster analysis （based on relative peak area of common peaks in fingerprint ）were performed for 20 batches of samples by SPSS 21.0 software. RESULTS：The average contents of morusin and total flavonoids in M. alba were 0.096 0-0.618 6 mg/g，0.48％-1.51％，which were significantly correlated with each color index （P＜0.01）. The smaller L＊，b＊，E＊ab and the larger a＊were，the higher the content of morusin was ；the higher the value of L＊，b＊，E＊ab and the smaller the value of a＊were，the higher the content of total flavonoids was. The similarity between the fingerprints of 20 batches of samples and the control ranged from 0.883 to 0.983；13 common peaks were demarcated ，and No. 1 peak was identified as chlorogenic acid. K-means cluster analysis showed that 20 batches of samples could be divided into 2 categories. Category Ⅰ were mainly from Anhui province with higher content of morusin，lower content of total flavonoids ，darker and yellowish brown color ；category Ⅱ were mainly from Sichuan province and Guizhou province ，with lower content of morusin ，higher content of total flavonoids ，lighter and yellowish white color. The results of hierarchical cluster analysis were consistent with the results. CONCLUS IONS：The color of M. alba is closely related to the contents of morusin and total flavonoids. The content of morusin in yellow-brown M. albais is higher ，while the content of total flavonoids in yellow-white M. albais is higher.

Effect of ceramic materials on the optical properties of porcelain veneers for tetracycline-stained teeth / 华西口腔医学杂志

OBJECTIVES@#To analyze the chromatic properties and translucency of porcelain veneers made from different ceramic materials against the background of tetracycline-stained teeth.@*METHODS@#Porcelain specimens (A1, A3, B2, B4) measuring 0.50 mm in thickness were prepared by heat-press casting and layering. The L*, a*, and b* values of the specimens against simulated tetracycline tooth and black-and-white backgrounds were measured by a spectrophotometer, and color differences ΔE@*RESULTS@#The ΔE@*CONCLUSIONS@#When changing the color of tetracycline-stained teeth, 0.50 mm-thick IPS d.SIGN feldspathic veneers with an opaque layer provide better chromatic properties than IPS e.max Press LT glass ceramic veneers. However, the translucency of feldspathic veneers is generally poorer than that of glass ceramic veneers.

Obtención de un colorante a partir de corteza de maracuyá con el uso de técnicas convencionales de extracción / Obtaining a dye from passion fruit cortex with the use of conventional extraction techniques

RESUMEN El maracuyá es un fruto tropical que se cultiva primordialmente para la obtención de pulpa, siendo la corteza su principal subproducto que carece, en la actualidad, de interés industrial; sin embargo, con el fin de diversificar los derivados provenientes de la producción de maracuyá, se ha demostrado que la corteza contiene carotenoides, dentro de los que se destaca el β-caroteno y la luteína, que podrían ser utilizados en alimentos, debido a su poder antioxidante e, incluso, como colorante natural alternativo. Por lo anterior, el objetivo de este trabajo fue obtener un extracto rico en carotenoides a partir de su corteza; para ello, se evaluó la extracción con etanol, mediante tres técnicas: inmersión, baño termostático y soxhlet. El mayor rendimiento, se obtuvo con el método soxhlet; para esta técnica, se estudió el efecto de la concentración de etanol (entre 80% y 90% v/v), la proporción solvente-materia prima (con relaciones entre 40:1 y 50:1) y el tiempo (definido entre 90 y 150 minutos). Los resultados, se analizaron mediante modelo de superficie de respuesta, obteniendo el mayor rendimiento con etanol al 90%, utilizando 50mL/g corteza y 150 minutos de operación. A estas condiciones, el rendimiento de extracción fue de 2208,53µg β-caroteno/100g muestra. Por último, se determinó la diferencia de color entre el extracto óptimo y una solución de tartrazina, evidenciando una diferencia de color de 3,07 unidades cieLAB, lo cual, muestra que el producto de lixiviación de la corteza de maracuyá tiene potencial para su uso como aditivo alimentario, reemplazando colorantes sintéticos, como la tartrazina.

ABSTRACT Passion fruit is a tropical fruit that is usually cultivated to obtain pulp, being the cortex its main not exploited by-product, because of the actual absence of industrial interest. However, with the aim of diversifying the derivates from the production of passion fruit products, it has been demonstrated that the cortex contains carotenoids, such as β-carotene and lutein; which could be used in food due to its antioxidant capacity, or even like a food colorant. Therefore, the objective of this work was to obtain a carotenoid-rich extract from its cortex; for this, three techniques of extraction with ethanol were evaluated, by immersion, thermostatic bath and Soxhlet. Being the last technique that one with which the best yield was obtained. With the highest yield technique, the following factors were evaluated: ethanol concentration on 80% and 90% v/v, solvent-raw material ratio on 40:1 and 50:1 and time on 90 and 150min. The best yield was obtaining to 90% ethanol, 50mL solvent/g raw material and 150min, for an extraction yield of 2208.53µg β-caroten/100 g sample. Finally, the color difference between the optimal extract and a tartrazine solution was determined, evidencing a color difference of 3.07cieLAB units; this shows that the passion fruit leaching product has the potential to be used as a food additive, replacing synthetic dyes such as tartrazine.

Intra- and inter-brand color differences of denture teeth under different illuminations

Abstract Debonding, staining and wear are usually the reasons for denture teeth replacement by new ones from same or different brands. Objective This study investigates the possible differences in color of denture teeth of the same or different brands under different illuminations, since their metameric behavior in color under specific illumination may become unacceptable. Methodology For the purpose of this study, 10 denture teeth (#11), shade A3, of 4 different brands were selected (Creopal/KlemaDental Pro, Executive/DeguDent, Cosmo HXL/DeguDent, Ivostar/Ivoclar-Vivadent). Teeth stabilized in white silicone mold and the CIELAB color coordinates of their labial surface under 3 different illumination lights (D65, F2, A) were recorded, using a portable colorimeter (FRU/WR-18, Wave Inc). ΔE*ab values of all possible pairs of teeth of the same brand (n=45) or pair combinations of different brands (n=100) under each illumination light, in a dry and wet state were calculated. Data were analyzed statistically using 3-way ANOVA, Friedman's and Wilcoxon's tests at a significance level of α=0.05. Results The results showed that brand type affected significantly L*, a* and b* coordinates (p<0.0001), illumination a* and b* coordinates (p<0.0001), but none of them was affected by the hydration state of teeth (p>0.05). Intra-brand color differences ranged between 0.21-0.78ΔΕ* units with significant differences among brands (p<0.0001), among illumination lights (p<0.0001) and between hydration states (p=0.0001). Inter-brand differences ranged between 2.29-6.29ΔΕ* units with significant differences among pairs of brands (p<0.0001), illumination lights (p<0.0001) and hydration states (p<0.0001). Conclusions Differences were found between and within brands under D65 illumination which increased under F2 or A illumination affected by brand type and hydration status. Executive was the most stable brand than the others under different illuminations or wet states and for this reason its difference from other brands is the lowest. In clinical practice, there should be no blending of teeth of different brands but if we must, we should select those that are more stable under different illuminations

Quality Analysis of Atractylodes chinensis with Different Growth Years by HPLC-QAMS Combined with Color Difference Principle / 中国药房

OBJECTIVE：To simultaneo usly determine the contents of atractylenolide Ⅱ ，β-eudesmol，atractyloxin and atractylone in Atractylodes chinensis ，and to evaluate the quality of A. chinensis with different growth years combined with color difference principle. METHODS ：HPLC method was adopted. The determination performed on Agilent Eclipse XDB-C 18 column with mobile phase consisted of acetonitrile- 0.2％ phosphoric acid （gradient elution ）at the flow rate of 1.0 mL/min；the detection wavelengths were set as 208 nm（atractylenolide Ⅱ，β-eudesmol），340 nm（atractyloxin）and 220 nm（atractylone）；the sample size was 15 μ L. Using atractyloxin as reference，QAMS was adopted to establish relative correction factors （RCFs） of atractylenolideⅡ，β-eudesmol and atractylone ；the content of each component in A. chinensis with different growth years were calculated. The contents of above 4 components were determined by external standard method and then compared with the results of QAMS. The color difference values of A. chinensis powder were measured based on color difference principle. The correlation analysis of above 4 components content with color was carried out by Pearson correlation analysis. RESULTS ：The separation degree of atractylenolide Ⅱ，β-eudesmol，atractyloxin and atractylone in A. chinensis was higher than 1.5. The linear range were 1.01-10.10，3.30-33.00，4.40-44.00，5.34-53.40 μg/mL，respectively. RSDs of precision ，reproducibility and stability tests were all lower than 2％，while the average recovery rates were 101.34％-104.67％（RSD＜1.5％，n＝6）. Using atractyloxin as reference ， RCFs of atractylenolide Ⅱ，β-eudesmol and atractylone were 3.896 7，5.928 2，9.727 9，with RSD of 0.35％，2.89％，0.36％ （n＝6），respectively. Relative deviation of 3 components （except for atractyloxin ） in 24 batches of A. chinensis ranged 0.03％-1.45％ between QAMS and external standard method ，which indicated that the results of two methods were consistent ，and the content of each component increased with the increase of growth years. Atractylenolide Ⅱ，β-eudesmol，atractyloxin and atractylone in A. chinensis had significant negative correlation with its color shade （L*），total color difference （E*ab）（P＜0.01）， and significant positive correlation with color red-green direction （a*）， color yellow-blue direction （b*）（P＜0.01）. CONCLUSIONS：The established HPLC-QAMS method can be used for the determination of atractylenolide Ⅱ，β-eudesmol， atractyloxin and atractylone in A. chinensis . The longer the growth period is ，the higher each component content is. The color of A. chinensis is closely related to the content of each component ，and the content of effective components is higher in A. chinensis with dark yellowish brown color.

Correlation Between Effective Components Content and Color Values of Gentianae Radix et Rhizoma Based on Color Difference Principle / 中国实验方剂学杂志

Objective:To measure the color values of Gentianae Radix et Rhizoma and the contents of gentiopicroside,the appearance index value of the representative color was correlated with the intrinsic index value representing the quality,in order to explore the correlation between the contents of active ingredients and the color values,and provide basis for the quality evaluation of Gentianae Radix et Rhizoma. Method:The color difference values of Gentianae Radix et Rhizoma powder was measured by colorimeter.The content determination method of gentiopicroside in the 2015 edition of China Pharmacopoeia was adopted. The content of gentiopicroside was determined by HPLC,and the correlation and regression analysis was carried out by SPSS 21.0 software. Result:There was a significantly positive correlation between the contents of gentiopicroside and L* (representing colorshade)and E* ab(representing total color difference)(Pa* (representing color red-green direction) and b* (representing color yellow-blue direction) had a significantly negative correlation (PConclusion:The color value of Gentianae Radix et Rhizoma has a certain correlation with the content of gentiopicroside,and yellowish Gentianae Radix et Rhizoma contain more active ingredients, with a better quality.The contents of gentiopicroside active ingredients in Gentianae Radix et Rhizoma can be quickly predicted by determining the color difference values,which can provide a new idea for quality evaluation of this herb.

Optical properties of computer aided design and computer aided manufactured materials for veneer restorations / 中华口腔医学杂志

Objective@#To investigate the translucency parameters (TP) and the color parameters of computer-aided design and computer-aided manufacturing (CAD/CAM) materials for veneer restorations in order to guide clinical practice.@*Methods@#Eleven groups of CAD/CAM materials (A2 shade) were included in this study: IPS e.max CAD HT/LT, IPS Empress CAD HT/LT, LavaTM Ultimate HT/LT, VITA SUPRINITY HT/T, VITA ENAMIC HT/T, VITABLOCS Mark Ⅱ, and were named as Group A, B, C, D, E, F, G, H, I, J, K. Each material was designed and milled to disk-shaped specimens (10.0 mm×8.0 mm×0.7 mm) (n=6). The specimens were polished with silicon carbide paper and the thickness of specimens were adjusted into (0.60±0.03) mm. The color parameters of specimens were individually measured with the colorimeter against black and white ceramic tiles background to obtain the TP values. The color parameters of the specimens against the composite resin background were also measured and the color differences (ΔE values) between specimens and the A2 shade tab were calculated.@*Results@#One-way ANOVA showed that the translucency parameters of the 11 groups of materials were statistically significant (F=253.69, P<0.05). The ΔE values of CAD/CAM material groups ranged from 1.78 to 4.12 (ΔE values<5.5).@*Conclusions@#The microstructure of CAD/CAM materials and the types of material translucency influence the optical properties. The CAD/CAM materials in this experiment have achieved color matching with the A2 shade tab.

Bleaching of stained resin using nitrogen doped-TiO₂ nanoparticles / 대한치과재료학회지

There has been increasing use of the H₂O₂-based teeth bleaching agents. The purpose of this study was to evaluate the bleaching effectiveness of the laser irradiation combined with nitrogen doped-TiO₂ nanoparticles (NPs) on the stained resin. Nitrogen (N) doped-TiO₂ NPs were prepared under sol-gel method. Light absorbance, X-ray diffraction patterns of NPs, and bleaching of methylene blue and stained resins were evaluated. For bleaching of stained resin, NPs-containing gel was used. For irradiation, light of two different wavelengths was used. Unlike TiO₂, N-TiO₂ showed high absorbance after 400 nm. N-TiO₂, which have used TiN as a precursor, showed a new rutile phase at the TiN structure. For methylene blue solution, N-TiO₂ with 3% H₂O₂ resulted in the greatest absorbance decrease after laser irradiation regardless of wavelength. For stained resin test, N-TiO₂ with 3% H₂O₂ resulted in the greatest color difference after laser irradiation, followed by group that used N-TiO₂ without 3% H₂O₂.

Comparative study on the shade matching performance of dental students under D55 and D65 light sources conditions / 华西口腔医学杂志

OBJECTIVE@#This study aimed to compare the effect of D55 and D65 light sources on the visual colorimetry performance of dental students by using a homemade light-source shelf.@*METHODS@#Two Vitapan 3D-Master shade guides were randomly selected. One set was used as shade guides. Ten commonly used shade tabs of 2L2.5, 2M2, 2R2.5, 3M2, 3R2.5, 3L1.5, 3R1.5, 3L2.5, 4R1.5, and 4L1.5 were selected from the other set with covered value marks and numbered from 1 to 10. After the colorimetric training, 49 undergraduate dental students were randomly divided into two groups. Each student randomly selected two of the 10 shade tabs, and the colors were subsequently matched under D65 and D55 light sources from a distance of approximately 40 cm. The average color difference (ΔE) between the color selected by each participant and the actual color of shade tabs was calculated. Paired t test was used for statistical analysis.@*RESULTS@#The ΔE values between the color selected by each participant and the actual color of the shade tabs under the D55 light source varied from 0 to 6.540. The average value was 2.501. The ΔE values between the color selected by each participant and the actual color of the shade tabs under the D65 light source varied from 0 to 6.610. The average value was 2.530. No statistically significant difference was observed between the results under the two light sources (P=0.921).@*CONCLUSIONS@#Both D55 and D65 daylight lamps can be used for daily dental colorimetry. These two different color temperatures showed no significant difference.

Effect of resin cement color on the color of commercially available zirconia crown / 대한치과재료학회지

The purpose of this study is to evaluate the effect of resin cement color on the color of commercially available zirconia crown. The zirconia and resin cements used for the experiment were NuSmile® ZR Zirconia LT Shade (LT), RelyX™ U200 TR, A2, and A3O (TR, A2, A3O). The disks of zirconia and resin cements with diameters of 5 mm and thicknesses of 1 mm were prepared. Five disks were made for each specimen. The CIE L*a*b* values of zirconia, resin cements and the combinations thereof were measured on black and white backgrounds, respectively, using a spectrophotometer. The color effect of resin cement on the color of the zirconia crown was evaluated by calculating translucency parameter (TP), contrast ratio (CR), and color differences (ΔĖ(ab)) based on the measured CIE L*a*b* values. The statistical significances were verified by one-way ANOVA and the Tukey-multiple comparisons tests. As a result, the TP and CR values were decreased (p < 0.05) and increased, respectively, in the combination of zirconia and resin cement disks compared to zirconia disk per se. When using the black background, the ΔĖ(ab) values between zirconia and the combination of the zirconia and three resin cement disks were imperceptible level. The A3O showed the lowest ΔĖ(ab) value among three resin cements. When using the white background, the ΔĖ(ab) values between zirconia and the combination of zirconia and TR resin cement (LT/TR) disks showed acceptable level. However, the ΔĖ(ab) values between zirconia and the combination of zirconia and A2 resin cement (LT/A2) disks showed unacceptable level. Meanwhile, the ΔĖ(ab) values between zirconia and the combination of zirconia and A3O resin cement (LT/A3O) disks showed perceptible but acceptable level. Within the limits of this study, the colors of resin cements did not cause unacceptable color changes of zirconia except the combination of LT/A2 on the white background. The resin cement that gave the least color changes to zirconia was A3O. This means that the resin cement A3O is recommended to use for minimizing color changes when cementing commercially available zirconia crown to tooth.

Correlations between colors and contents of nine active constituents of Salvia miltiorrhiza with four growth years / 中成药

AIM To study the correlations between colors and contents of nine active constituents of Salvia miltiorrhiza Bge.with four growth years (one,two,three and five years).METHODS The chromatic values (L*,a* and b*) were determined by precise color difference meter.HPLC was applied to determining the contents of water-soluble constituents (lithospermic acid,salvianolic acid B,rosmarinic acid,protocatechuic aldehyde acid and salvianic acid A sodium) and liposoluble-soluble constituents (dihydrotanshinone Ⅰ,cryptotanshinone,tanshinone Ⅰ and tanshinone Ⅱ A).Then the correlations between colors and contents of various constituents were investigated by Pearson correlation analysis.RESULTS L* and b * values of two growth-year S.miltiorrhiza,together with a* value of three growth-year S.miltiorrhiza,were the highest,but various chromatic values of five growth-year S.miltiorrhiza were all the lowest.The contents of various constituents in three growth-year S.miltiorrhiza reached the highest.Lithospermic acid and salvianic acid A sodium showed no significant correlations with various chromatic values,salvianolic B,rosmarinic acid and tanshinone Ⅱ A exhibited significantly positive correlations with them,and protocatechuic aldehyde had significantly negative correlations with them.CONCLUSION The quality of three growth-year S.miltiorrhiza is relatively high.

Repeatability and reproducibility of individual abutment impression, assessed with a blue light scanner

PURPOSE: We assessed the repeatability and reproducibility of abutment teeth dental impressions, digitized with a blue light scanner, by comparing the discrepancies in repeatability and reproducibility values for different types of abutment teeth. MATERIALS AND METHODS: To evaluate repeatability, impressions of the canine, first premolar, and first molar, prepared for ceramic crowns, were repeatedly scanned to acquire 5 sets of 3-dimensional data via stereolithography (STL) files. Point clouds were compared and the error sizes were measured (n=10, per type). To evaluate reproducibility, the impressions were rotated by 10-20° on the table and scanned. These data were compared to the first STL data and the error sizes were measured (n=5, per type). One-way analysis of variance was used to assess the repeatability and reproducibility of the 3 types of teeth, and Tukey honest significant differences (HSD) multiple comparison test was used for post hoc comparisons (α=.05). RESULTS: The differences with regard to repeatability were 4.5, 2.7, and 3.1 µm for the canine, premolar, and molar, indicating the poorest repeatability for the canine (P<.001). For reproducibility, the differences were 6.6, 5.8, and 11.0 µm indicating the poorest reproducibility for the molar (P=.007). CONCLUSION: Our results indicated that impressions of individual abutment teeth, digitized with a blue light scanner, had good repeatability and reproducibility.

The optical property of four different all-ceramic crowns on the light color core ND1 substructure / 实用口腔医学杂志

Objective:To evaluate the optical property of the light color core substructure ND1 overlaid by 4 different all-ceramic crowns respectively and to study the color difference between the crowns and target tab.Methods:Light color(ND1)substructures were made and were respectively tried in 4 groups of all-ceramic crowns (Procera alumina,Procera zirconia,Lava zirconia and IPS E.max glass-ceramic lithium disilicate-reinforced monolithic,n =10).The CIE L*,a*,b* values of the cervical part,body and incisal site of the samples were recorded and analyzed by a spectrophotometer before and after veneer.The color difference between the all-ceramic crowns and target A2 dentin tab was evaluated.The spectral integral transmittance of the 4 copings was measured by a spectrophotometer.Results:The L* values of the abutments was increased by all-ceramic copings of the 4 groups,a*values were decreased but b* changed inconsistently.After veneer,the L* values of all the copings declined significantly,the values of a* and b* increased.When compared with A2 tab,the ΔE of the crowns was 1.27 ~4.17.The mean value range of the transmittance of the coping was:E.max-LT A2 >Pro-Alu >Lava-Zir >Pro-Zir.Conclusion:The lightness,hue and light transmittance of the 4 ceramic copings are different.After veneer with A2 dentine,the difference of the lightness is declined but the difference of the hue is signifi-cant.The color difference of the Lava-Zir and IPS E.max is clinically unacceptable.

Research on color differences between enamel and dentin of natural teeth / 第二军医大学学报

Objective To investigate the color differences of enamel and dentin of natural teeth, so as to lay a foundation for reducing the color differences of natural dentin and core of all ceramic restorations. Methods X-rite Color i7 Spectrophotometer was used to examine the chroma value and chromatic difference (δE) of enamel and dentin of natural teeth (thickness 0. 9 mm, 0. 6 mm and 0. 3 mm, n = 30). Results The L* values (lightness) of enamel and dentin increased with the decrease of slice thickness, and the a* values (red-green) and b* values (yellow-blue) decreased with the decrease of slice thickness (P<0. 05). The absolute L*, a* and b* values of the dentin were significantly greater than those of enamel of same thickness (P<0. 05). There were great color differences between enamel and dentin of different thicknesses, with the mean δE values within a range of 5. 303-13. 109. The color difference gradually increased with the thickness increase of enamel and dentin. The δE value of the enamel and dentin of the same thickness was 5. 115 (0. 9 mm), 5. 855 (0. 6 mm), and 6. 053 (0. 3 mm), respectively. Conclusion There is noticeable color difference between the enamel and dentin of natural teeth, and the difference increases with the increase of their thickness difference. The dentin has a more yellowish color and less lightness compared with the enamel. So each laminate of all ceramic restorations needs a shade selection for all ceramic restorations, and more attention should be paid on the color matching of natural dentin and core ceramic laminate.

The evaluation of color and color difference according to the layering placement of Incisal shade composites on the body composites of the indirect resin restoration / 대한치과보존학회지

OBJECTIVES: The aim of this study was to evaluate the surface color of indirect resin restoration according to the layering placement of different shade of incisal composite. MATERIALS AND METHODS: In this study, CIE L*a*b* value of 16 Body composite of Tescera ATL (Bisco, Schaumburg IL,USA) was measured by spectrophotometer (NF999, Nippon Denshuku, Japan), and compared to CIE L*a*b* value of Vitapan shade guide. Nine shade Incisal composite of Tescera ATL were build-up to 1 mm thickness on Body composites inlay block, and CIE L*a*b* value was measured. Incisal composite was ground to 0.5 mm thickness and CIE L*a*b* value was re-measured. Color difference between Body composite and Incisal composites layered on Body composite was calculated as a function of thickness. RESULTS: Color difference between corresponding shade of Tescera Body composite and Vitapan shade guide was from 6.88 to 12.80. L* and b*value was decreased as layering thickness of Incisal composite on Body composite was increased. But, a* value did not show specific change tendency. CONCLUSIONS: Surface color difference between Body composites and Incisal composites layered on Body composite was increased as the layering thickness of Incisal composite increased (p < 0.05).

Influência de três iluminantes (D65, A e F2) e da rugosidade superficial de dentes artificiais de resina composta na percepção da diferença cor entre profissionais da odontologia / Influence of three illuminants (D65, A and F2) and surface roughness of composite resin artificial tooth on the difference color perception among dental professionals

Este estudo avaliou a influência de três iluminantes e da diferença na rugosidade superficial de réplicas de dentes artificias na percepção da diferença de cor entre profissionais da Odontologia e verificou se houve variação na opinião de 20 profissionais uma semana após a primeira avaliação. O único critério de exclusão dos participantes foi a deficiência na visão cromática, avaliada através da versão simplificada do teste de Ishihara. Dos 117 profissionais entrevistados, 6 (5,1%) homens e 11 (9,4%) mulheres foram excluídos do estudo, pois identificaram incorretamente 1 ou mais pranchas da versão simplificada do teste de Ishihara. Neste estudo foram utilizados 4 pares de réplicas de dentes artificiais, sendo que cada par foi confeccionado em resina composta nas cores A1, A3, B1 ou B2, porém uma réplica apresentava superfície lisa e a outra, superfície rugosa. Todas as avaliações foram realizadas em cabine de luz sob os iluminantes D65, A e F2. Para cada iluminante, os participantes foram questionados se havia diferença de cor entre as réplicas. Após uma semana, todo o experimento foi repetido por 20 profissionais selecionados aleatoriamente. A análise dos resultados sugeriu que os iluminantes e a diferença na textura superficial influenciaram a percepção da diferença cor entre as réplicas e que após uma semana houve variação na opinião dos observadores.

This study evaluated the influence of three different illuminants and the difference on surface roughness of artificial teeth replica on the color difference perception among dental professionals and if there were variations on 20 professionals opinion 1 week after the first evaluation. The color vision deficiency was the only exclusion criteria used and a screening for color defective vision was conducted by using the simplified version of Ishihara test. Among the 117 professionals interviewed, 6 (5.1%) men and 11 (9.4%) women who missed 1 or more plates did not take part in this study. The test was composed by 4 pairs of artificial composite resin teeth replicas was confectioned with the same color A1, A3, B1 or B2, but the surface of one replica was smooth and the surface of the other one was rough. All the evaluations were conducted in light booth with D65, A and F2 illuminants. In each illuminant the participants were asked if there were color difference between the replicas. After one week, all the experiment was repeated by 20 participants randomly selected. The analysis of the results suggested that the illuminant and the difference on surface texture influenced the difference color perception between the replicas and reaffirm that the professionals opinion varied after one week of the first evaluation.

Comparison of the properties of three denture base materials treated and untreated by hydraulic pressure cooker / 实用口腔医学杂志

Objective:To compare the properties of three kinds of denture base materials treated and untreated by hydraulic pressure cooker. Methods: The impact strength, flexural strength, flexural elastic modulus and color difference roughness of three denture base materials, Kunshan Rijin(KR),GC UNIFAST Trad(GC), Shanghai Zhangjiang(SZ), were measured in vitro. All results were statistically analyzed with SPSS software to have ANOVA and Tamhane's T2 tests, α=0.05. Results: Comparison of the same materials between the treated materials and the untreated materials by hydraulic pressure cooker: there were significant statistical differences of impact strength for all the materials. There were significant statistical differences of color difference for KR and SZ. Comparison of the three materials: impact strength, GC>SZ>KR;flexural strength, KR>SZ>GC;flexural elastic modulus, KR>SZ>GC;roughness, GC>KR>SZ. Conclusion: The properties of denture base materials treated by hydraulic pressure cooker are good.

Color difference of the dental composites measured by different color measuring instruments / 대한치과보존학회지

The objective of this study was to evaluate the effect of color measuring instrument by measuring the color of dental composite resins. Nine shade light cured composite resin disks were prepared (diameter : 15 mm, thickness : 4 mm). CIE L*a*b* color scale of each disk was measured with 3 different types of spectrophotometer [MiniScan XE plus (Model 4000S, Hunter Lab, USA), CM-3500d (Minolta, Japan) and Specbos 2100 Miniature VIS Reflection spectrometer (Serial No: 319416, JETI Technishe VIS Instrumentic GmbH, Germany)]. Miniscan XE Plus and CM-3500d using identical measuring geometry with different size of viewing aperture. But Specbos 2100 using different measuring geometry. Within the limitation of this study, there were color difference (DeltaE*) from 2.4 to 7.8 between Miniscan XE Plus and CM-3500d, but L*, a*, b* values showed the high correlation. However, there were great color difference (DeltaE*) in the extent of about 20 between instruments with the different measuring geometry. Therefore, color scale measured by color measuring instrument should be used as a relative value rather than an absolute value in the field of dentistry.