Surface Color Change Research Articles

Evaluation of carbonated fossil bone consolidation by induction of calcium hydroxide nanoparticles in a Miocene Cheirogaster richardi specimen

In this research, calcium hydroxide nanoparticles, as a carbonate consolidation method, have been evaluated on carbonated fossil bone samples from decontextualized Cheirogaster richardi specimens’ fragments.The main objective was to assess whether the treatment improved fossil bone surface cohesion and mechanical strength by creating a consolidated carbonate matrix in fossil substrate. Treatment penetration capacity and chemical compatibility without causing observable alterations in substrate porosity and external appearance were considered as significant questions to be assessed. Samples were analysed both before and after treatment using scanning electron microscopy, spectrophotometry, weight measurement control, water absorption assessment, conductivity and pH measurement, Vickers microindentation and tape testing. During analysis and evaluation, changes in fossil bone after treatment compared to its original condition have been taken into account.Results point out that hardness and cohesion increased significantly after treatment, bonding together disaggregated particles via a calcium carbonate micrometric layer, with almost negligible changes in surface topography and colour. In addition, calcium hydroxide nanoparticles penetration depth was remarkable. Conductivity, pH and weight hardly changed and porosity reduction was observed without complete pore blockage. To sum up, the treatment was effective and suitable for carbonate fossil bones having a highly compatibility with carbonate fossil bones substrates.

Mechanical, optical and surface properties of 3D-printed and conventionally processed polyamide 12.

Polyamide-based materials are suitable for three-dimensional (3D) printing. The aim of the study is to examine the impact of aging on the mechanical, surface and optical properties of polyamide 12. A total of 116 specimens were examined, comprising 58 conventionally processed polyamide 12 (PA12_C) specimens and 58 3D-printed polyamide 12 (PA12_3D) specimens. The modulus of elasticity was determined before and after mechanical and thermal aging with 1,000, 3,000, 9,000, and 1,000, 3,000 and 7,000 cycles, respectively. The surface roughness (Ra), Ra change (ΔRa) and color change (ΔE) were examined before and after chemical aging (1, 12 and 36 days, with artificial saliva, coffee and red wine) using surface profilometry and color spectroscopy. The Kruskal-Wallis test, Mann-Whitney U test and Bonferroni-Holm correction were employed, with a significance level of p < 0.05. Before and after mechanical aging, the modulus of elasticity for PA12_3D showed significantly higher values (761 MPa and 747 MPa, respectively) in comparison to PA12_C (515 MPa and 455 MPa, respectively; adjusted p < 0.001). Additionally, before and after thermal aging, the modulus of elasticity for PA12_3D exhibited significantly higher values (833 MPa and 705 MPa, respectively) compared to PA12_C (516 MPa and 458 MPa, respectively; adjusted p < 0.001). The Ra of PA12_3D was higher than that of PA12_C at the baseline (0.41 μm compared to 0.31 μm, respectively), and remained higher during the aging process. The ΔRa values were small for both groups. The ΔE was significantly higher for PA12_3D compared to PA12_C after 12 days (6.2 (PA12_3D) compared to 4.8 (PA12_C), adjusted p = 0.003) and 36 days of storage in red wine (8.2 (PA12_3D) compared to 6.8 (PA12_C), adjusted p = 0.003). After 36 days of coffee storage, the observed changes were found to be statistically significant (8.6 (PA12_3D) compared to 6.7 (PA12_C), adjusted p < 0.001). The 3D-printed polyamide 12 demonstrated higher rigidity, Ra and discoloration compared to the conventionally processed polyamide 12. However, not all of the observed parameter differences were significant or clinically relevant. These differences may impact clasp retention, biofilm formation and aesthetic appearance. Nevertheless, the clinical efficacy of 3D printing may be significant.

The effect of diode 980 nm laser-activated bleaching on surface roughness and color change in composite resin restorations (in vitro study)

The effect of diode 980 nm laser-activated bleaching on surface roughness and color change in composite resin restorations (in vitro study)

The effect of whitening toothpastes on the surface properties and color stability of different ceramic materials

ObjectivesThis study aimed to evaluate the effect of whitening toothpastes on the surface roughness and colour change of CAD-CAM materials.Materials and methodsA total of 96 samples (2 × 10 × 12 mm3) were prepared from Cerasmart (CS) and Celtra Duo blocks. Celtra Duo samples were divided into two groups. One group was fired with glaze paste (CDG) and the other was not treated (CD). All groups were then divided into 4 subgroups (n = 8). The groups were brushed with conventional (Colgate™ Max Fresh), silica (Opalescence™), charcoal (Curaprox™ Black in White) and blue covarine (Signal™ White Now) toothpastes for 30,000 brushing cycles. The initial and final surface roughness values were measured with contact profilometer and a dental spectrophotometer used for obtaining colour values. One sample from each brushed group was analyzed using a scanning electron microscope. Data was analyzed with Kruskal-Wallis and Mann-Whitney tests (p = 0.05).ResultsThe surface roughness of CS samples brushed with Opalescence™ and Curaprox™ was significantly higher than CD and CDG. Surface roughness change values of CS samples brushed with Curaprox™ were significantly higher than the CD and CDG. Curaprox™ brushed samples showed significant difference in colour change values for all materials.ConclusionsBrushing increases the surface roughness of CAD-CAM ceramic materials. The roughness of resin-based materials is higher than zirconia-reinforced lithium silicates. Silica-contained toothpastes may cause discoloration of nanoceramic and zirconia-reinforced glass ceramic restorations.Clinical relevanceIt should be clinically considered that whitening toothpastes may cause roughness in ceramic materials and change the desired color.

Can wheel polishers improve surface properties and color stability of monochromatic resin composites?

BackgroundTo overcome the color layering procedure, monochromatic resin composites have been introduced. However, little is known about their polishability, gloss and color stability. This study aimed to investigate the surface roughness, gloss, and color change of monochromatic resin composites polished with wheel systems after being immersed in coffee.Materials and methodsOmnichroma, Zenchroma, Essentia Universal, Charisma Diamond One and NeoSpectra ST were used to obtain 120-disc samples of 8 × 2 mm. Only one side of the sample was polished with Twist Dia (TWD) or Nova Twist (NOV). The samples were examined for surface roughness, gloss, and color (ΔE and ΔE00) before and after 7 days of immersion in coffee and subsequent repolishing. The discs were examined via SEM. Surface roughness and gloss values were analyzed using ANOVA, Tukey and Pearson correlation tests. ΔE and ΔE00 values were evaluated using T tests, multivariate ANOVA, and Dunnett’s post-hoc tests.ResultsFor TWD groups, the smoothest material was Omnichroma (p < 0.05), while for NOV groups, it was Omnichroma and Zenchroma. Omnichroma was the glossiest, while Charisma Diamond One was the least glossy. In TWD groups, Charisma Diamond One and Essentia Universal were the most discolored, while Zenchroma and Omnichroma were the least. For NOV groups, Essentia Universal and Charisma Diamond One were the most discolored, while NeoSpectra ST, Omnichroma and Zenchroma were the least. After repolishing, Charisma Diamond One did not reach the level of ΔE < 2, while the other groups showed values below. Color evaluation with the CIELab and CIEDE2000 systems revealed similar results for the TWD groups after post-staining.ConclusionsSmooth and glossy surfaces could be achieved with the wheel system regardless of the composite resin. Repolishing after discoloration ensures that the color recovery is below the acceptable limit. Color evaluations with CIELab and CIEDE2000 yielded similar results.

Nanosecond pulsed laser coloring of the CrMnFeCoNi high entropy alloy

High-entropy alloys (HEAs) possess great potential for applications in the aerospace and military fields due to their excellent performance. Surface coloring can endow HEAs diverse functions. However, achieving a multi-color surface with minimal surface damage and cost remains a significant challenge. In this study, surface coloring of the CrMnFeCoNi HEA was attempted by nanosecond pulsed laser irradiation in air, and the multi-color surface was achieved. The evolution of surface color and morphology with laser parameters was analyzed. Then, five typical colors were selected, and the corresponding morphologies and chemical compositions were characterized by various techniques. The results showed that the change in oxide layer thickness as well as the formation of chromium-rich β-spinel and Cr (VI) compounds induced noticeable changes in surface color. Accordingly, complex surface patterns with various stable colors were prepared on the HEA surface, demonstrating the potential application of nanosecond pulsed laser coloring of HEAs.

Effect of cigarette smoking and carbonated beverages on the surface roughness and color change of two single-shade resin composite: In-vitro study

Effect of cigarette smoking and carbonated beverages on the surface roughness and color change of two single-shade resin composite: In-vitro study

Analysis of discharge parameters of an argon cold atmospheric pressure plasma jet and its impact on surface characteristics of White Grapes

An argon cold atmospheric-pressure plasma (CAP) jet operated using bipolar pulsed power supply has been characterised electro-optically and the discharge parameters are optimized. An analysis has been done on the impact of the argon CAP jet treatment on the surface properties of white grapes for different treatment time period. The developed argon CAP jet is a plasma source based on dielectric barrier discharge (DBD) that has been tuned at various input parameters including applied voltage, frequency, average power consumption, and argon flow rate. Optical Emission Spectroscopy (OES) is used to identify the generated species along with plasma parameters. The collisional–radiative (CR) model is employed to extract the electron density (ne) and electron temperature (Te) from the spectra at the optimised applied voltage of 4 kV, frequency 20 kHz and argon flow rate of 4 slpm. The OES results coupled with the CR model (ne ∼ 1014 cm−3 and Te ∼ 1 eV) and the plasma gas temperature measurement through OH (A-X) transitions (Tg ∼ 310.5 K) show the non-equilibrium nature of the argon CAP jet. A comparative analysis between untreated and treated white grapes reveals that the argon CAP jet treatment influences surface microstructure, increasing hydrophilicity (with a ∼49.3% decrease in water contact angle) along with slight changes in surface temperature (∼5 °C increase), colour (ΔE* < 1.5), and physiochemical properties such as chemical composition (no change) and Total Soluble Solid (TSS) content (∼8.3%). It is inferred that this type of CAP jet treatment of white grapes only affects the physical characteristics of the grape surface and does not alter any chemical compositions.

Bamboo durability: Understanding the combined effect of weathering and mildew infection

Bamboo has been widely used in outdoor applications and heat treatment is a typical industrial technique for improving its durability. Weathering and mildew are the two main types of deterioration that occur on bamboo. However, there are few studies on the deterioration of bamboo properties and degradation mechanism under such combined effect. Therefore, in this study, the effect of weathering on the mildew infection value (MIV) of natural bamboo (NB) and heat-treated bamboo (HB) were compared. The changes in surface color, morphology, and chemical composition of NB and HB during accelerated UV weathering were characterized. Meanwhile, the MIV of bamboo samples after different weathering durations was evaluated and the influencing mechanism was explored. The results revealed that the decomposition of starch and hemicellulose during heat treatment resulted in the generation of levoglucosan and acids, thereby providing a new nutrient source and a more suitable environment for mildew growth. HB exhibited superior color stability and anti-weathering characteristics compared to NB. Moreover, certain photodegradation products from HB demonstrated anti-fungal and anti-weathering properties, which resulted in a temporary resistance to mildew in weathered samples. However, after long-term exposure, the cracks on the surface of HB caused by weathering facilitated the colonization of mildew hypha by releasing inner nutrients, leading to severer mildew infection.

Efficient removal and separation of cationic dyes by microbubbles for electroflotation coupling membrane electrosorption

In order to enhance the treatment efficiency of cationic dyes wastewater, a dual chamber reactor was ingeniously designed to combine electroflotation and electrosorption technologies. The electrochemical system effectively removed representative single and mixed cationic dyes within 64 min at 150 mA. The observable reaction process phenomena, microbubble photos, clear Tyndall effect phenomena, and electrochemical experimental results all indicated the crucial role of electroflotation in removing cations dyes. Furthermore, changes in surface color, morphology, and functional groups of the anion exchange membrane before and after electrolysis suggested that the electrosorption process also contributed significantly to the removal process. Analysis using UV–vis absorption spectrum and high-resolution mass spectroscopy indicated that no significant chemical reaction occurred with the cationic dye during this process; thus, confirming that the separation of the cationic dye was a physical removal process. This study provides valuable theoretical guidance for efficient removal and separation of cationic dyes in wastewaters.

Investigation of effects of environmental conditions on wear behaviors of glass fiber reinforced polyester composite materials

AbstractGlass fiber reinforced polymer (GFRP) composites can be subjected to different environmental conditions such as temperature, humidity, ultraviolet radiation, hydrothermal cycle, acidic and alkaline solution in environments where they operate. These environmental conditions cause different damage mechanisms in composites such as pore formation, micro‐cracks, delamination, fiber breakage, fiber/matrix interface separation, plasticization, swelling and surface color change. In this study, wear properties of hybrid glass fiber reinforced polymer composites exposed to various environmental conditions for constant load (60 N), speed (500 rpm) and 2 h were examined comprehensively, depending on material content and environmental conditions. In this experimental study, the service conditions in glass fiber reinforced composites were simulated using different artificial aging environments such as acidic environment, hydrothermal cycle and UV radiation. In addition to the material content, it appears that the environmental conditions to which composites are exposed has a significant effect on friction coefficient. Considering environmental conditions, it is seen that the acid environment and hydrothermal cycle have reduced wear resistance of GFRP composites, while UV radiation improved wear resistance of the composites. In C2 sample, the wear rates under different conditions are 1.87 × 10−14 m3/Nm in non‐treated sample, 6.05 × 10−14 m3/Nm in acid environment, 4.79 × 10−14 m3/Nm in hydrothermal cycle and 0.59 × 10−14 m3/Nm in UV radiation.Highlights Friction coefficient of glass fiber reinforced polyester (GFRP) is higher under aged condition compared to non‐treated. Glass fibers used in correct proportions can reduce friction coefficient in GFRP. GFRP exposed to environmental conditions has an important effect on wear. Acid environment and hydrothermal cycle has reduced wear resistance of GFRP. UV radiation improved wear resistance of GFRP composite.

In Vitro Kinetic and Thermodynamic Staining Study of Three Energy Drinks on the Restorative Charisma Composite

Abstract Aim: The research utilized charisma composite resin, a dental restorative material known for its esthetic properties, with the chemical formula 2,2-bis[p(2-hydroxy-3-methacryloxy propoxyphenyl)] propane. The primary objective of the study was to examine the overall color change (ΔE*ab) of the charisma resin after it was subjected to three distinct energy drink solutions: Monster Energy Ultra-Sunrise, Wild Tiger, and Red Bull. Further we examined the effects of temperature and time on the staining interaction and overall color difference ΔE*ab on the surface of charisma restorative resin generated by three energy drink. Materials and Methods: A microfilled Charisma Classic composite resin was used in presented comparative study selected. The prepared 144 composite disk samples (subdivided n=48) with random allocation method were used for the three energy drinks to determine the effect of temperature and time over the course of 90 days. A metallic circulator mold was prepared. Every set of 48 specimens in the energy drink was heated in a water bath for 1, 7, 30, 60, and 90 days at four different temperatures This investigation spanned various time intervals, ranging from 1 to 90 days, and encompassed four temperature levels between 283 and 310 K. One-way ANOVA was used to evaluate the mean data for color change between the energy drinks, and Tukey’s post hoc test was used for multiple comparisons, with a significance level of P &lt; 0.05. Results: The study revealed that the rate of staining was most pronounced in the case of Wild Tiger, while it was comparatively lower for Monster Energy Ultra-Sunrise. These findings were established through an examination of the kinetic and thermodynamic behavior of surface color changes in micro-hybrid composites treated with the three energy drink solutions. Conclusions: The observed patterns aligned with the pseudo second-order model. It was observed that the Red Bull drink displayed a negative activation energy, resulting in a slower color change rate with increase in temperature. In contrast, endothermic, spontaneous, and regular staining activity was demonstrated throughout time by Monster Energy Ultra-Sunrise and Wild Tiger.

The impact of Streptococcus mutans biofilms on the color stability and topographical features of three lithium disilicate ceramics.

Secondary caries around ceramic restorations is the most common reason for the replacement of fixed dental prostheses (FDPs). Therefore, it is important to examine the susceptibility of different ceramic materials to biofilm formation. This study aimed to evaluate biofilm development and associated roughness and color alterations in three lithium disilicate ceramics: Emax CAD (EC), Emax Press (EP), and LiSi Press (LP). Streptococcus mutans biofilms were grown on the three ceramics (n = 10 per group) for 7 days. Surface roughness values and color alteration were assessed before and after the biofilm using a non-contact profilometer and spectrophotometer, respectively. Biofilm growth was evaluated using colony-forming units (CFUs) and scanning electron microscope (SEM) images. The data were analyzed using one-way ANOVA and Tukey tests. There was a significant (p≤0.001) growth of S. mutans colonies on EC (6.75 ± 0.56) and EP (6.72 ± 0.54) specimens compared to LP, which showed no biofilm growth. The change in average surface roughness (∆Ra, nm) was significantly lower (p < 0.001) in the EC specimens (0.029 ± 0.003) compared to the EP (0.055 ± 0.012) and LP (0.041 ± 0.010). When the changes in the Rv and Rt values were investigated, no significant difference was observed among the groups. Following the biofilm challenge, the change in color (∆E00) was significantly lower (p = 0.005) in the LP group (1.68 ± 1.45) compared to the EC group (3.89 ± 1.50) and no significant difference was observed between the EP group (2.74±1.01) and the other two ceramics (p ≥ 0.05). LP ceramics exhibited superior resistance to S. mutans biofilm formation and associated changes in surface roughness and color compared to the Emax CAD and Emax Press ceramics. These findings suggest that the LiSi Press material may be more favorable to mitigate the risk of secondary caries.

Can energy drinks affect the surface quality of bioactive restorative materials?

BackgroundsThis study aimed to compare the effects of different energy drinks on the surface roughness, weight loss, and color change of various bioactive restorative materials.MethodsCharisma Diamond One, Activa™ BioActive Restorative, Activa™ Presto™ and Equia Forte HT Fil samples were prepared using plastic molds (8 × 2 mm) (n = 10/groups). After polishing, the samples were weighed, their colors were recorded using a spectrophotometer according to the CIEDE2000 system, and their surface roughness was measured using a profilometer. The samples were immersed in Powerade, Burn, Monster and distilled water for 7 days. After immersion, all the measurements were repeated. Statistical analyses were performed using the Wilcoxon signed-rank test and the Mann‒Whitney U test (p < 0.05).ResultsAll energy drinks roughened the surface of Equia Forte HT Fil (p < 0.05). Powerade and Monster increased the Ra of all materials after 7 days (p < 0.05). Burns affected all materials except the Activa Bioactive (p < 0.05). Significant weight loss was observed in the Equia Forte group after immersion in all the energy drinks, whereas no weight loss was observed in the other groups. According to the color measurements, ΔE00 values were greater in the Burn and Monster groups, except for the Equia Forte HT Fil group (p < 0.05).ConclusionEnergy drinks affected bioactive materials to varying degrees. The glass hybrid material was the most affected, and the bioactive restorative materials based on the resin matrix were the least.

Effect of 25% Tobacco Leaf Extract (Nicotiana Tabacum L.) as a Denture Cleaning Paste on Surface Roughness and Color Change Thermoplastic Nylon

Thermoplastic nylon as a denture base requires mechanical cleaning with denture paste. Previous research showed that tobacco leaf extract paste (TLEP) 25% was fungistatic on thermoplastic nylon denture bases. The aim is to evaluate the roughness and colour changes of thermoplastic nylon against tobacco leaf extract paste 25% during one year of simulated use. This research hypothesizes that thermoplastic nylon's roughness and colour value will decrease further after brushing using 25% TLEP. Sample groups include brushing without paste, paste without TLEP 25% and TLEP 25%. The sample size for each group was 15 samples; measurements use a surface roughness tester and a colour reader. Brushing was carried out for 23.5 minutes on a plate measuring 60x10x2.5 mm as a surface roughness test and 3.90 minutes on a plate measuring 10x10x2.5 mm as a colour change test. The sample size for each group was 15 samples; measurements use a surface roughness tester and a colour reader. The research results were tested using Kolmogorov-Smirnov and Levene and One-way ANOVA with a significance level of 0.05. There were no differences in surface roughness and colour changes on thermoplastic nylon plates after brushing with 25% TLEP (p0.05). This study concluded that 25% TLEP did not affect increasing surface roughness and changing the colour of thermoplastic nylon plates with values below the threshold.

Surface Characteristics and Artificial Weathering Resistance of Oil-Based Coatings on the Chemically and Thermally Modified Short-Rotation Teak Wood.

Improving the durability of short-rotation wood can be achieved through chemical and thermal modification. Chemical and thermal modification can have an impact on the physicochemical properties of wood, which can affect wood's surface characteristics and its resistance to weathering. The purpose of this study was to investigate the surface characteristics and artificial weathering resistance of chemically and thermally modified short-rotation teak wood coated with linseed oil (LO)-, tung oil (TO)-, and commercial oil-based coatings consisting of a mixture of linseed oil and tung oil (LT) and commercial oil-based polyurethane resin (LB) coatings. The short-rotation teak woods were prepared in untreated and treated with furfuryl alcohol (FA), thermal treatment (HT) at 150 and 220 °C, and combination of glycerol-maleic anhydride (GMA) impregnation with thermal treatment at 150 and 220 °C. The surface characteristics measured were surface free energy, wettability, Persoz hardness, bonding quality, and color changes before and after artificial weathering exposure. The results showed that chemical and thermal modifications treatment tended to reduce total surface free energy (SFE), hardness, wettability, and bonding quality. FA and GMA at 220 °C treatments provided homogenization effect on surface characteristics, especially in total SFE and wettability. The total SFE of untreated wood ranged from 45.00 to 51.13 mN/m, and treated wood ranged from 40.58 to 50.79 mN/m. The wettability of oil-based coating according to K-value ranged from 0.20 to 0.54. TO presented better photostability than LO. Short-rotation teak wood coated with oil-based commercial coatings presented better weathering resistance compared to pure natural drying oil. Commercial oil-based coatings provided better weathering protection for the chemically and thermally modified teak wood. The application of oil-based coatings on chemically and thermally modified short-rotation teak is being considered for the development of a better wood-protection system.

Transparent bamboo as a replacement for glass: Effects of lignin decolorisation methods on weatherability

Transparent bamboo proved to be a promising substitute for glass due to its high light transmittance and excellent mechanical properties. Nevertheless, it was susceptible to outdoor weathering, which negatively affected its physical and mechanical properties. In this study, two decolorisation methods, namely the delignification method and the lignin modification method, were used to produce transparent bamboos with epoxy resin, referred to as DL-TB and LM-TB, respectively. The changes in surface color, optical and mechanical properties, wettability, thermal stability, and thermal insulation properties of transparent bamboo during accelerated UV weathering were evaluated. Additionally, the deterioration mechanism of DL-TB and LM-TB was investigated. The findings revealed that DL-TB demonstrated better transparency and mechanical properties than LM-TB, although it exhibited lower thermal insulation properties. Furthermore, DL-TB demonstrated enhanced color stability and higher hydrophobicity on weathered surfaces than LM-TB. Unexpectedly, the tensile properties of both two transparent bamboos significantly improved after weathering, especially for LM-TB, which was due to the EP post-curing and the formation of more hydrogen bonds between lignin and EP. These observations revealed that lignin played a key role in the photodegradation process of transparent bamboo, but further attempts should be made in future studies to improve its color stability.

Enhancing Esthetics in Direct Dental Resin Composite: Investigating Surface Roughness and Color Stability.

Dental restorations must replicate the natural appearance of teeth while ensuring biocompatibility and durability. This study evaluated the surface characteristics and color stability of three dental composites-Herculite Ultra XRV, G-ænial A'CHORD, and Omnichroma-exposed to acidic beverages (red wine, black coffee, and Coca-Cola). Sixty disk-shaped specimens were prepared, polished, and immersed in these beverages. Surface roughness was assessed using profilometry and SEM analysis, hydrophobicity via contact angle analysis, and surface charge through streaming potential measurements. Color stability was evaluated using a spectrophotometer, and the pH levels of the solutions were recorded. Results showed that Herculite Ultra XRV had the highest mean contact angle (79.46° ± 6.52), indicating superior hydrophobicity, while Omnichroma had the lowest (64.94° ± 3.08), indicating more hydrophilicity. Significant color changes were observed, especially in black coffee, with ∆E values indicating notable discoloration. The acidic pH of the solutions increased surface roughness and color changes. Statistical analyses confirmed significant increases in surface roughness and color change for all composites, with the nanohybrid resin composite showing the greatest variability. These findings highlight the need for dental restorative materials with enhanced resistance to acidic environments to improve the longevity and esthetics of dental treatments.

The effect of nano propolis on surface color changes of nanohybrid composite resins

Background: Nanohybrid composite resins have many advantages, but one disadvantage is their absorbent nature which can lead to discoloration. Phenols and flavonoids in nano propolis cause diffusion and affect the matrix and pigments of nanohybrid composite resins. The accumulation of reduction-oxidation reactions causes new compounds of nanohybrid composite resins to occur so that they have different colors. Objective: The study was conducted to determine the changes in surface color of nanohybrid composite resin after immersion in nano propolis at 5% concentration. Methods: Research experimental laboratory method with pre and post test design was applied to 25 nanohybrid composite resin fruit samples of size (5x5x1.5) mm embedded in bovine incisive, then immersed in 5% nano propolis and 25 ml of distilled water at 37oC for five days. The color change (ΔE) was measured with a DSLR camera and processed with Adobe Lightroom Classic software in CIE L*a*b* format. Results: The anova test on ΔE in the data showed the p-value of sphericity assumed was smaller than 0.05. There is a difference in the average measurement results on the first day to the fifth day in the treatment group. Independent t-test of control and treatment data showed a significant difference in measurement results. The results of the post hoc test with the Tukey method showed that the treatment groups at 4x24 hours and 5x24 hours did not have significant differences. P-value at 4x24 hours and 5x24 hours was 0.957. Conclusion: There was a change in the surface color of the nanohybrid composite resin after being immersed in a nano-solution of propolis with a concentration of 5%.

New approach for deacidification and consolidation of bone artifacts

Acidic conditions affect the archaeological bone in the burial and in uncontrolled display and storage environment or due to improper restoration processes. Accordingly, bones become weak and fragile. This study aims to evaluate nano calcium propionate and nano styrene butyl acrylate (used for the first time in the treatment of bones) at different concentrations for deacidification and consolidation of fragile bones. New bone samples were prepared. Artificial accelerated aging (acid and heat) was applied to prepare aged untreated samples. Deacidification and consolidation processes using the materials mentioned above were applied. The analytical techniques used were transmission electron microscope (TEM) and thermal gravimetric analysis (TGA) were used for morphological and thermal stability investigation for the prepared nano styrene butyl acrylate copolymer and its calcium propionate nonocomposites, a digital microscope and scanning electron microscope (SEM) for investigation of the surface morphology, pH value measurement, change of color measurement, attenuated total reflection—Fourier transform infrared spectroscopy (ATR/FTIR), contact angle (wettability), and X-ray diffraction analysis for measurement of bone crystallinity. The results proved that acid-heat aging affected bone properties such as changes in surface morphology and color, decrease in pH value, and contact angle. Bone samples became more crystalline, and the chemical composition of bone was also affected. The treatment of aged untreated bone samples with the materials used in this study improved their properties, such as increasing the pH value and contact angle. The surface morphology, color change, and crystallinity of bone improved and became more stable.