Color Change Values Research Articles

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.

Engineering Fano resonances in plasmonic metasurfaces for colorimetric sensing and structural colors

In this paper, we present the design and fabrication of a plasmonic metasurface based on titanium dioxide (TiO2) nanowire arrays integrated with plasmonic layers. The structure is engineered to produce Fano resonances within the visible spectrum, resulting from the coupling of localized surface plasmon resonances, lattice modes, and nanowire's optical modes. Experimentally, we show that by tuning the geometrical features of the metasurface, such as the length, diameter, and period of the nanowires, a high-quality factor single peak can be achieved in the reflection spectra, resulting in vivid structural colors in bright field. To our knowledge, this is the first demonstration of such vivid colors with nanowire arrays in bright field reflections. When characterized by refractive index fluids around the refractive index of water, the plasmonic metasurface also showed great potential for biochemical colorimetric sensing. The best design demonstrated a bulk sensitivity of 183 nm/RIU with high Q resonance features and linear changes in color values using image processing.

Evaluation of the Effect of Background Color on the Color Change of Composite Resins of Different Translucencies

Aim: To evaluate the effect of background color on the color change evaluation of composite resins of different translucency. Material and Method: In our study, Estelite ∑ Quick (EQ) CE, OA2 and Filtek Ultimate (FU) A2 Enamel, A2 Dentin composites were used. Disc-shaped samples were prepared from the composites of both brands by layering enamel and dentin alone and enamel + dentin (n=10). After preparation, samples were kept in distilled water for 24 hours and then in coloring solution (NescafeClassic) for 10 days. Colors of the composite samples were measured with a spectrophotometer (VıtaEasyshade) on black, white and gray backgrounds after 24 hours (initial) and after coloring. Color change value (ΔE00) was calculated using two measurement values for each background. Color change values of the same composites measured on different backgrounds were compared. Additionally, the ΔE00 values of different translucent tones from the same company were compared on different backgrounds. One-way ANOVA and Tukey's post-hoc tests were used for statistical analysis. (α=0.05). Results: When used layered with dentin, enamel composites consistently showed lower ΔE00 values than enamel composites alone (p<0.05). When comparing ΔE00 values of the same composite resin samples on different background colors, the ΔE00 values measured on black background were found to be higher only for FU enamel compared to the values measured on the other two backgrounds (p<0.05). When different translucent shades from the same company were compared on different backgrounds, the ΔE00 ranking was found to be enamel > dentin >/=mine + dentin for all backgrounds. Conclusion: Different backgrounds did not affect the color evaluation of samples containing an opaque composite resin, dentin composite; however, they did affect the color evaluation of FU enamel, which is a translucent composite resin. When translucent composite resins are layered with more opaque composite resins, more accurate color evaluation can be achieved.

Artificial intelligence as a tool for predicting the quality attributes of garlic (Allium sativum L.) slices during continuous infrared-assisted hot air drying.

Effective drying methods are a highly suitable solution for ensuring stable food supply chains, reducing postharvest agricultural losses, and preventing the spoilage of perishable fruits and vegetables. Moreover, machine learning techniques are innovative and dependable, especially in addressing food spoilage and optimizing drying processes. This study utilized a continuous infrared (IR) hot air dryer to dry garlic (Allium sativum L.) slices. The experiments were conducted at different levels of IR power, air velocities (V), and temperature (T). The relationships between the input process parameters (IR, T, and V) and response parameters, including effective moisture diffusivity (Deff), drying time, and physicochemical properties of the dried slices (rehydration ratio [RR], total color change, flavor strength, and allicin content in the garlic), were modeled using an artificial neural network (ANN). Our findings showed that the maximum Deff of 6.8×10-10m2/s and minimum drying time of 225min were achieved with an IR of 3000W/m2, an air velocity of 0.7m/s, and a temperature of 60°C. The total color change and RR values increased with IR and higher air temperature but declined with higher air velocity. Furthermore, the garlic's flavor strength and allicin content levels decreased as the IR and air temperature increased. The results demonstrated a significant influence of the independent parameters on the response parameters (p<0.01). Interestingly, the ANN predictions closely matched the test data sets, providing valuable insights for understanding and controlling the factors affecting drying behaviors.

Effect of Listerine and Chlorhexidine mouthwashes with antidiscoloration system on the colour change of CAD/CAM conventional and novel lithium disilicate ceramics

Background It has been reported that using mouthwashes can discolour the surface of teeth. Their effect on the stainability of newly introduced lithium disilicate ceramics is, however, unknown. Objective: The purpose of this in vitro study was to investigate how mouth washes affected the color change of new and conventional lithium disilicate (LS2) ceramics that were finished using various techniques. Materials and Methods A total of 56 ceramic slices were produced from conventional LS2 (E Max CAD, Ivoclar) and a novel virgilite based LS2 (Cerec Tessera, Dentsply Sirona). According to the finishing method, the specimens were divided into glazed and polished subgroups. Each subgroup was further subdivided into two based on immersion in chlorhexidine (CHXD) or Listerine (LIST) mouth washes. A handheld spectrophotometer was used to measure the color attributes, and color differences (ΔE00) were then counted using specific equation. Data were analyzed using ANOVA and Tukey’s post-hoc tests. Results Significant differences in color change (ΔE00) values were observed between conventional and novel LS2 ceramics, as well as between different finishing methods and mouth-rinse solutions. Chlorhexidine induced higher color differences than Listerine, with average ΔE00 values of 0.959 and 0.885, respectively (p &lt; 0.001). The polished specimens generally exhibited higher ΔE00 values than the glazed specimens, with average values of 1.071 and 0.792 for conventional LS2, and 0.836 and 0.786 for novel LS2 (p &lt; 0.001). However, most color changes did not exceed the perceptibility and acceptability thresholds. Conclusion Using CHXD and LIST mouth washes affected the color change of polished or glazed conventional and novel lithium disilicate ceramics. In general, the stainability of polished specimens was higher than that of glazed ones. There was more discoloration on specimens immersed in CHXD than those immersed in LIST. Bangladesh Journal of Medical Science Vol. 23 No. 04 October’24 Page : 1178-1184

Fluorinated B-72 hybrid silver doped modified nanoparticle as a coating for biological corrosion protection of ancient bricks

In this paper, a superhydrophobic organic-inorganic composite coating containing fluorinated B72 hybrid methyl-modified silica/(Ag doped TiO2) by hexamethyldisilazane (HMDS) (H-SiO2/Ag/TiO2) was prepared by means of a mild and an environmental friendly method. Transparency, adhesion, hardness tests and photocatalytic performance were measured to determine the content of Ag in TiO2 which the TiO2/AgNO3 ratio is 0.008 g/mL. The synthesized Ag/TiO2 nanoparticles were characterized by X-ray diffraction (XRD), Raman spectra and transmission electron microscope (TEM). The highest contact angle of coated ancient bricks was 148.66° and the color change value of ΔE⁎ before and after coating was <5 which is within an acceptable range. The physical properties such as apparent porosity and water vapor permeability (ΔMp) were studied. After weathering from acid, alkali, salt, water and ultraviolet radiation, the bricks coated by the composite coatings still have good hydrophobicity that the contact angle were >120° and minor degree of surface corrosion comparing with the ancient bricks. The inhibitory effect of the composite coating on Staphylococcus aureus (S. aureus) and Escherichia coli (E. coli), and that on algae (Chlamydomonas and Dunaliella) were studied through bacteriostasis test and algae comparative experiments, respectively. Finally, the mechanism of the composite coating on antibacterial and anti-algae was studied. The results showed that the appearance of the ancient bricks was not changed after coating, and the anti-weathering, antibacterial and anti-algae properties of the ancient transformation were increased.

Refractance window drying of Spanish cherry (Mimusops elengi Linn) pulp: Impacts on drying kinetics, color, and phytochemical properties

In present study, Spanish cherry pulp (SCP) was dried using refractance window (RW) dryer at varying temperatures (50 to 90 °C) to investigate the impacts on drying kinetics and physicochemical properties and compared with freeze-dried samples. An increasing RW drying temperature from 50 to 90 °C reduced drying time from 320 to 80 min. The water and oil absorption capacity showed no significant (p < 0.05) changes in RW-dried SCP samples. Noticeable changes in color values, ascorbic acid, β-carotenoid, total phenol content, total flavonoid content, and antioxidant activity were observed on increasing RW drying temperature. As per results, compared to control, RW drying at 50 °C retained most of the nutrients. From nutrient retention perspective, RW drying at 80 and 90 °C may not be suitable SCP samples. From multivariance analysis, RW drying of SCP samples can be performed at 60 °C instead of 70 °C for better nutrient contents.

Effect of Packaging Material and Storage Period on Popping Behaviour of Roasted Makhana Seeds

The effect of storage period and type of packaging material on the popping behaviour of roasted makhana seeds was studied. Raw makhana seeds with a diameter of 9-10 mm were roasted using a batch-type primary roasting machine and tempered for 48 hours to bring the roasted seed moisture content to about 16% dry basis (d.b.). The roasted seeds were stored in 15, 25, and 80 µm Low-Density Polyethylene (LDPE), 110 µm Polypropylene (PP), 140 µm Biaxially Oriented Polypropylene (BOPP), and 60 μm Silver Laminate (SL) packets for six months. Popping of the stored seeds was conducted at 15-day intervals, and observations were made on popped makhana recovery, popping efficiency, colour of popped makhana, and expansion characteristics. The expansion ratio, expansion index, popped makhana recovery and popping efficiencies prior to storage were 2.37±0.22, 13.64±4.04, 48.53±0.50, and 82.89±0.78%, respectively. Duncan’s multiple range tests showed that the seeds packed in 15 µm LDPE packages maintained the quality and recovery up to 60 days only. The 80 μm LDPE packets, BOPP, PP, and SL packets were found effective in maintaining popping efficiency, recovery of popped makhana, and expansion ratio more than 81.44±0.70%, 47.95±0.43%, and 2.14±0.14, respectively with no significant colour change up to 135 days storage of the roasted seeds. Significant changes in colour values of popped makhana were observed after 135 days of storage and a* value increased whereas L* and b* values decreased. This study showed that makhana seeds may be popped effectively with &gt;47% popped makhana recovery, &gt;16 mm average diameter and acceptable colour values up to 120 days when the roasted seeds are stored at 15.53±0.49% (d.b.) in airtight packaging material, which was not possible until now.

Comparison of optical properties and bond strength of new CAD/CAM ceramic materials

Objective. To compare the shear bond strength values of current CAD/CAM materials and to evaluate the color changes resulting from immersion in coloring solutions. Material and Methods. A total of 160 specimens were prepared from 4 CAD/CAM blocks; lithium disilicate glass ceramic (IPS E.max CAD[EC]), zirconia reinforced lithium silicate ceramic (Vita Suprinity[VS]), polymer infiltrated glass ceramic (Vita Enamic[VE]) and hybrid ceramic (GC Cerasmart [GC]). The ceramic specimens were immersed in tea, coffee, cherry juice and distilled water solutions. Color measurements were made. To compare the shear bond strength values, all specimens were bonded to resin cement. Then the specimens were aged with 5000 thermocycling. The failure modes were classified according to stereomicroscope analysis and than scanning electron microscopy images for surface topography were obtained. Results. The color change values were significantly greater in coffee compared to other solutions and the highest color change was seen in GC and VE. The highest bond strength values were seen in VS and VE. The shear bond strength values are listed as follows: VS>VE>EC>CS. Conclusions. EC and VS can be used, especially in aesthetic restorations, due to their high color stability. Additionally, considering the bond strength values of VS, it appears to be a highly satisfactory material.

An In-Vitro Study on the Impact of Light-Emitting Diode (LED) and Laser-Activated Bleaching Techniques on the Color Change of Artificially Stained Teeth at Varying Time Intervals.

Introduction Tooth color is a key factor in the perception of an attractive smile, making bleaching a widely sought-after cosmetic dental procedure. Valued for its minimally invasive approach, this technique effectively lightens teeth to achieve desired aesthetic outcomes. As the desire for immediate results grows among patients, various bleaching agents, and energy sources have been developed to expedite the bleaching process. The study aims to evaluate and compare the efficacy of 35% hydrogen peroxide activated by light-emitting diode (LED) and laser on artificially stained teeth, assessing color changes at different time intervals. Methodology Sixty maxillary central incisors with intact crowns were selected for the study. An artificial staining solution was prepared, and the samples were immersed in it for 15 days to simulate staining. After this period, the teeth were removed from the solution, rinsed with water, and dried. Baseline photographs of each tooth were taken for comparison. The teeth were then divided into two groups, one treated with LED activation and the other with laser activation of 35% hydrogen peroxide as the bleaching agent. The color changes were measured and recorded at different time intervals. Data were presented as mean and standard deviation, with statistical analysis conducted using independent sample t-test and repeated measures ANOVA to compare the efficacy of the two methods. Results Both LED and laser activation of 35% hydrogen peroxide demonstrated significant color changes in the stained teeth. The initial color improvement was noticeable in both groups, with LED and laser treatments producing comparable whitening effects. The mean color change values indicated that both activation sources were effective in enhancing the bleaching process, providing immediate and substantial results. Statistical analysis showed no significant difference between the two methods, suggesting their equivalency in clinical efficacy for tooth bleaching. Conclusion The study concludes that both LED and laser activation of 35% hydrogen peroxide are efficient methods for in-office tooth bleaching, providing immediate and enhanced whitening effects. The comparable results between the two energy sources indicate that can be effectively used to meet the increasing demand for rapid aesthetic improvements in a clinical setting. This finding supports the adoption of both LED and laser bleaching techniques as viable options for dental practitioners aiming to achieve optimal patient satisfaction with minimal invasiveness.

Changes in the physical, chemical and sensory properties of pasta made by partially substituting wheat flour with black glutinous rice flour

Black glutinous rice flour (BGRF) had the potential to be used as a wheat substitute to increase the health-promoting nutritional value of pasta products. The purpose of this study was to investigate the possibility of using BGRF as an alternative to wheat flour in the production of pasta to improve its nutritional value. The research explored the physical, chemical, sensory properties, and consumer acceptance of pasta formulations with 0%, 20%, 40%, and 60% BGRF substitution. The findings revealed that pigmentation of BGRF contributed to increased phenolic compounds and antioxidant properties, which impacted physical and chemical properties of the pasta. The results indicated that a 40% substitution of BGRF was well-liked by consumers, while a 60% substitution led to decreased acceptance. The physical properties of uncooked pasta (UC-PAS) and cooked pasta (CK-PAS), such as moisture content and color values, were significantly influenced by the percentage of BGRF substitution. Specifically, the moisture content of UC-PAS decreased with higher BGRF substitution, resulting in changes in color values. These changes included an increase in redness, as well as a decrease in lightness and yellowness. Additionally, the pigmentation of BGRF contributed to increased phenolic compounds and antioxidant properties, which affected physical and chemical properties of the pasta. The pasta’s cooking quality, including cooking time (CKT), cooking loss (CKL), and cooking yield (CKY), also showed significant differences with varying percentages of BGRF substitution. Furthermore, the proximate composition indicated that the percentages of ash, protein, fat, and fiber increased as the proportion of BGRF increased, with pasta containing 60% BGRF demonstrating the highest values for these properties. All these findings provide evidence that BGRF substitution had a significant positive impact on the physical, chemical, and sensory properties of pasta. For example, the pasta had better antioxidant properties and was well-accepted by consumers. The potential for enhancing the nutritional profile of pasta products by substituting wheat flour with BGRF is noteworthy. Key words: black glutinous rice, wheat, rice flour, pasta, antioxidant, bioactive compounds

Investigation of Various Finishing/Polishing Procedures on Color Stability of Composite Resins

Objective: The objective of this study was to assess the impact of various finishing and polishing systems on the color stability of composite resins treated with coffee. Methods: Fifty samples of each of nanohybrid and supra-nanohybrid composite resin materials were prepared and each material was randomly divided into 5 groups (n=10): Group 1: Control group (mylar strip), Group 2: One Gloss (one step), Group 3: One Gloss + polishing paste, Group 4: Soflex disk (multistep), Group 5: Soflex disk + polishing paste. The samples were colored in coffee solution for 144 hours to simulate six months of coffee consumption after polishing. The color of the samples before-after staining was measured with a spectrophotometer and ∆E00 values were calculated. Results: Material, polishing type and the interaction of these two parameters had a statistical effect on the color change values (p&amp;lt; 0,001). The ∆E00 values of supra-nanohybrid composite resin were higher than nanohybrid. Both materials exhibited color change above the thresholds of clinical perceptibility (PT&amp;gt; 0,8) and acceptability (AT&amp;gt; 1,8). In terms of polishing types, the highest ∆E00 was found in the control group and the lowest in the disk group. The additionally applied polishing paste caused a non-significant decrease in the color change of the single-step polishing system (p&amp;lt; 0,05) and a statistically significant increase in the multi-steps polishing system (p&amp;gt; 0,05). Conclusion: Considering the limitations of the study, it can be concluded that the use of multi-steps discs is more advantageous in preventing discoloration of composite resins.

Assessing the Color Stability of Polymethyl Methacrylate (PMMA) Dental Restorations Polished With a Novel Polishing Agent Derived From Pulverized Old Alginate Impressions.

Interim restorations are essential in restorative dentistry, serving as temporary solutions until permanent restorations can be placed. Polymethyl methacrylate (PMMA) is a promising solution for customizing teeth for removable dentures to match the exact requirements of patients. The color stability of these restorations is critical for patient satisfaction. PMMAis a widely used material for interim restorations due to its favorable properties. The study compares the color stability of PMMA interim restorations polished using traditional pumice versus Algishine, a novel polishing agent derived from pulverized old alginate impressions. The 3-D design software Geomagic Design X (3D Systems, Rock Hill, CA) created a standard tessellation language file of 2-cm radius circles. Sixty PMMA samples were milled and divided into two groups of 30 each. Group A samples were polished using pumice, while group B samples were polished with Algishine. Baseline color measurements were taken using a spectrophotometer (VITA Easyshade V, VITA Zahnfabrik, Bad Säckingen, Germany). The samples were then subjected to staining with coffee, tea, and red wine solutions for 30 days, simulating oral conditions. Post-staining color measurements were taken, and color changes (ΔE) were calculated at the seven-day (t1) and one-month (t2) mark. The Shapiro-Wilk test assessed normality, followed by a two-way ANOVA testto compare color change values at different time points. At t1 (seven days), there were no significant differences between groups A and B in the coffee and tea staining groups. However, significant differences were observed in red wine staining, with group B exhibiting lower ΔE values (0.14 ± 0.067) compared to group A (0.38 ± 0.076) (p < 0.01). At t2 (30 days), significant differences were noted in all staining groups. Group B consistently showed lower ΔE values: coffee (0.125 ± 0.084 vs. 0.236 ± 0.015, p < 0.01), tea (0.254 ± 0.087 vs. 0.391 ± 0.015, p < 0.01), and red wine (1.174 ± 0.045 vs. 1.309 ± 0.074, p < 0.01), indicating superior resistance to staining compared to group A. The results suggest that Algishine is more effective than pumice in maintaining the color stability of PMMA interim restorations. The novel polishing agent derived from old alginate impressions enhances esthetic longevity and provides an eco-friendly solution for recycling dental material waste. Algishine performs superiorly in preserving the color of PMMA interim restorations against common staining agents. Its application can potentially improve patient satisfaction and contribute to sustainable dental practices.

Clinical Performance of Computer-Aided Design (CAD)/Computer-Aided Manufacturing (CAM) Resin Nanoceramic Endocrowns in Restoring Molars: An In Vivo Study.

Background It is difficult to determine the optimal method for restoring endodontically treated teeth, as several factors affect this decision. Functional requirements and the amount of remaining coronal tissue are considered the most important factors in choosing the best restoration for those teeth. Endocrown was introduced as a conservative alternative for endodontically treated and coronally damaged teeth. Aim The aim of this study is to assess the clinical performance of the nanoceramic system for molar endocrowns by evaluating color change, gingival condition, prosthesis integrity, and the presence of secondary caries. Materials and methods The sample consisted of 20 endocrowns. The teeth were prepared with at least 2 mm of wall thickness and a cavity depth of 4 mm from the occlusal surface. The final impression was taken, and the prostheses were adhered using dual-cure resin cement. It was clinically evaluated according to clinical success criteria (United States Public Health Service) in terms of color stability, gingival indexes, integrity of the restoration, and the presence of secondary caries after a week, three months, six months, and a year. The statistical study was conducted using IBM SPSS Statistics for Windows, Version 23.0 (Released 2015; IBM Corp., Armonk, NY, USA), and the results were considered statistically significant at the 95% level of significance. The Friedman test was used to study the significance of the differences in the average values of color change, plaque index, and the integrity of the prostheses during follow-up periods. Results The study showed a gradual increase in the degree of color change with follow-up periods. Furthermore, there was no significant difference in the incidence of gingival changes, the integrity of the prosthetic margins, or the occurrence of secondary caries during the follow-up periods. Conclusions Within the limitations of this study, an endocrown made of CeraSmart nanoceramic is an acceptable option for crowning decayed and endodontic-treated molars with acceptable clinical performance.

PREVENTING OF MIGRATION IN FOOD CONTACT POLYVINYL CHLORIDE-BASED STRETCH FILMS WITH POLYLACTIC ACID LAYER

In this study, the effectiveness of biodegradable polylactic acid (PLA) coatings for the prevention of residues migrating through polyvinyl chloride (PVC) films was investigated. PLA films prepared in chloroform at concentrations of 5, 10, 15 and 20 wt% were heat sealed to PVC film surfaces in a hot press (130 °C, 5 min, 5 tons). Physical, mechanical, FTIR and migration analyses were performed on these two-layer films. With PLA coating, the thickness of the films increased, mechanical properties decreased and some changes in color values occurred. It was determined by FTIR that there was no structural change on both surfaces of the films as a result of hot pressing. From the overall migration analysis, no migration was observed in the tests with aqueous food simulants, while migration was detected in fatty food simulants. In the specific migration analysis by GC-MS, di-2-ethylhexyl phthalate (DEHP) migration decreased by 50% with PLA coating. It is concluded that PLA coating of PVC stretch films may be a promising application to reduce migration.

In Vitro Evaluation of Color and Surface Roughness Changes of Polyetheretherketone, Monolithic Zirconia, and Resin Nanoceramics Exposed to Staining Liquids.

This study aims to investigate color stability and surface roughness of polyetheretherketone (PEEK), zirconia, and hybrid ceramics while stored in different liquids. A total of 240 specimens were prepared from monolithic zirconia, PEEK, and hybrid ceramics. All specimens were polished using rubber sets with different grain sizes. Color parameters (L*, a*, b*) were measured three times using a dental spectrophotometer in standard D65 lightning. Each group was divided into eight different groups to be kept in eight different solutions as distilled water, cola, red wine, tea, coffee, heptane, citric acid, and 50% ethanol. Specimens were held in solutions at 37°C for 12 days. Color measurements were repeated, and color change (ΔE) was calculated using the CIE Lab formula. The color difference of PEEK specimens was found above the clinically acceptable limit; however, color differences for monolithic zirconia produced by coffee were found within the clinically acceptable limits. ZR and HC specimens' color change values were found between threshold values (1<ΔE < 3.3). The differences observed in surface roughness levels amongst the ZR specimens could be caused by the polishing instrument and procedure. The color change of the materials was within acceptable limits, whereas the surface roughness increased more than 0.2 µm. Especially cola, heptane, and red wine significantly increased the mean surface roughness.

Effects of thermal treatment on air-dried density, color change, average surface roughness, and sound absorption capacity of Scots pine

This study was conducted to investigate some characteristics of thermally treated Scots pine (Pinus sylvestris L.) wood specimens such as air-dried density, color change, average surface roughness, and sound absorption capacity. Heat treatment of Scots pine wood was performed at atmospheric pressure at 140, 160, 180, and 200 °C for 2 h. As a result, the air-dried density values of the thermally treated wood decreased as the temperature of the thermal treatment increased. With the increase of thermal treatment temperature, an increase in total color change values was detected on the surfaces of the samples and the color of the samples became darker. The average surface roughness (Ra) value of samples improved due to thermal treatment conditions and the highest value was determined in thermally treated samples at 200 °C as 3.59 μm. At 140 °C the value of maximum sound absorption coefficient was observed to be 0.48 at 2500 Hz and the highest sound transmission loss value, which was 36.7 dB, was measured at 6300 Hz and at 200 °C.

The effects of continuously wetting-drying cycles on pre-weathered and oil-coated rowan (Sorbus torminalis) wood

The naturally weathered and then oil-coated (Teak oil) Rowan wood (Sorbus torminalis) was subjected to distilled (A) and swimming pool water (B) aging treatments with continuous wetting-drying up to the third cycle. Treatment conditions and water aging types seem to influence color variables somewhat. The highest lightness (ΔL*), redness (Δa*), and yellowness (Δb*) changes were measured in samples that were continuously aged at the third cycle procedure in swimming pool water, respectively. Similar results have also been observed for total color changes, such that pool water had higher discoloration effects on color values compared to distilled water at similar conditions, while increasing the cycle usually further lowered discoloration. The highest color change value of ΔEB3: 10.49 (metric) was found in the third cycle in pool water treatment, followed by a value of ΔEB2: 9.42 (metric) in the second cycle and a value of ΔEB1: 1.71 (metric) in the first cycle, respectively. Color changes could be employed as a sensitive physical indicator of coating aging, which can be correlated to the associated chemical changes. All aging processes have lower gloss values than control in all aging procedures, regardless of water type. The lowest gloss value of 1.2 GU was noticed at the third cycle in swimming pool treatments. It is also notable that the most dramatic effect on surface hardness (Shore D) was found after the first cycle, while the lowest hardness values of 38 (metric) and 33 (metric) were found in swimming pools and distilled pure water-treated samples, respectively.

Color Stability and Surface Roughness of Different Composite Resins after Using Different Polishing Systems.

Background and objectives: To evaluate and compare the color stability and surface roughness of different composite resins after using different polishing systems and then submitting to accelerating artificial aging (AAA) and staining by black tea. Method: Twenty disk-shaped specimens (were compacted into the custom-made cylindrical plastic mold that had an internal diameter of 10 mm and a depth of 2 mm) were prepared for each composite resin type (3M Z350, Tokoyama palfique and shofu Beautifil II) for a total of 60 specimens, each composite group was divided into two subgroups according to the polishing system (n=10) (Shofu super-snap polishing disks and Eve Diacomp Plus Twist wheel). Color parameters (L*, a*, and b*) and surface roughness were measured before and after accelerating artificial aging (2000-4000 thermal cycle) and staining. Results: It was observed that all resin-based materials showed an increase in color change value and surface roughness values after 2000 thermal cycles. while after 4000 thermal cycles only the surface roughness value decreased in all resin-based materials. Conclusion: all resin-based materials showed clinically acceptable color stability and surface roughness &gt;0.2 µm) after (2000 thermal cycle) and staining. Keywords: color stability, surface roughness, thermal cycle, staining.

Development of a cabin for fast freezing in a household refrigerator and examination of its effects on the quality characteristics of beef

In this study, a cabin design was made for fast freezing in household refrigerators using different fan types (radial fan velocity of 1100, 1500 and 1900 rpm) and axial (1350 rpm) and the effects on the quality characteristics of beef were examined. Before the freezing process, the beef (Semitendinosus) was sized at 10 × 10 × 2 cm as a single fillet; 2 × 2 × 2 cm as the cubed sample and the minced beef was prepared by the butcher from the same meat and shaped with the dimensions of 10 × 10 × 2 cm. It was seen that when the fan velocity was 1900 rpm during the freezing process, the weight (0.39–11.61 %) and cooking loss (26.69–44.66 %) values of the beef samples decreased. A decrease was observed in the TBARS values (0.34–0.87) of the sample as the radial fan velocity increased in radial fan. When the total color change values (3.96–7.59) of all beef samples were examined, it was seen that the least color change was achieved with the axial fan before and after cooking. When the textural properties of the meat were examined before and after cooking, it was observed that the hardness decreased as the radial fan velocity increased, and the lowest hardness value was obtained from freezing with the axial fan. In addition, porosity values decreased and protein denaturation temperatures increased due to the formation of smaller ice crystals with the axial fan. As a result, it has been observed that fan type and velocity have significant effects on accelerating the freezing process and preserving the quality of beef samples.