Highest Color Change Research Articles

Ionic liquids functionalized Fe3O4-based colorimetric biosensor for rapid determination of ochratoxin A.

Astainless steel mesh (SSM) with the feature of flexibilitywas employedas the colorimetric biosensor substrate, and aptamer was bond onto the surface of theSSM. Through the cross-linking of ionic liquids (ILs), AuPt nanoparticles were deposited onto the surface of Fe3O4 material to obtain a magnetic nanozyme with high peroxidase catalytic activity and rapid color change. Through the competinginteraction of OTA and cDNA with aptamer, AuPt@IL@Fe3O4 signal probe was separated to catalyze the 3,3',5,5'-tetramethylbenzidine/hydrogen peroxide (TMB/H2O2) system to observe the color by bare eyeand record the absorbance at 652 nm using a UV-spectrophotometer. Through the study of the catalytic properties on the basis of the Michaelis equation, AuPt@IL@Fe3O4 nanozyme presented a Vmax of 3.85 × 10-8 M s-1 and Km of 0.01 mM. Under the optimized conditions, the linear range of the colorimetric biosensor towards OTA was 5-100 ng mL-1, and the detection limit was 0.078 ng mL-1. This biosensor was applied tobeer and corn samples with recoveries of 70.4-102.6% and 93.3-104.7%, respectively. Results showed that this sensor is aportable, rapid,economical, sensitive visual sensing platform towards mycotoxin in real samples.

The effect of varnish type, glue amount, and density on the surface properties of low density particleboards produced from waste wood bark

Particleboards, which are widely used in various fields, are commonly coated with solid and liquid surface coating materials to achieve better physical, mechanical, and aesthetic results. This study produced low-density particleboards from waste wood bark using different adhesive mixtures and densities. These particleboards were then coated with three types of varnish: water-based (Aq), polyurethane-based (Pu), and oil/wax-based (Ow). The color, gloss, and surface roughness values of the coated boards were determined to investigate the effect of varnish type, total adhesive usage, and density on these properties. In the board groups produced with the same glue ratio and density, the roughness values obtained with Ow varnish application were mostly higher compared to Aq and Pu. In the Ow varnish type, the roughness (Rmax) decreased linearly with increasing total adhesive amount in particleboards produced at low density (320 kg/m3). The highest color change (ΔE*) values for all variations were obtained in the Ow varnish type, while the highest gloss values were achieved at 85° and in the B2 (4%-420 kg/m3) board group. It was concluded that higher density should be preferred for smoother and glossier surfaces, which are important in terms of surface properties and aesthetics. Overall, these findings highlight the preference for higher density to achieve smoother and glossier surfaces in areas where surface properties and aesthetics are significant.

Does hot coffee or cold coffee cause more discoloration on resin based composite materials?

This study aimed to examine the effect of beverages at different temperatures on the coloring of composites. A total of 48 cylindrical samples, 24 of which were prepared from 2 composite materials (G'aenial; Estelite Σ Quick), were included in the study. The sample dimensions were standardized at 2 x 10 mm2. After the polishing, the initial color measurements were performed using a spectrophotometer. The samples were divided into 3 subgroups as distilled water, hot coffee (60 °C) and cold coffee (0 °C) (n=8). During the 7th and 30th days, the samples were immersed in the solutions for 15 min every day. Color measurements were repeated on the 7th and 30th days. Data were analyzed using a two-way analysis of variance, followed by the Tukey post-hoc test (p<0.05). The highest color change was detected on the 7th and 30th days in the G-aenial anterior microhybrid composite immersed in hot coffee (p<0.001). The application of hot and cold coffee applications did not make a statistically significant difference in the coloration of the Estelite Σ Quick composite samples at the end of the 7th (p=0.346) and 30th (p=910) days. Hot drinks had a more coloring effect on restorations. This coloration was quite evident in the microhybrid composite.

An In Vitro Staining Effect of Different Children's Health Drinks on Esthetic Restorative Materials.

To evaluate the staining effect of different children's health drinks (Boost, Complan, and Pediasure) on esthetic restorative materials (giomer, nanohybrid composite, and ormocer). The specimens consist of giomer, nanohybrid composite, and ormocer. Before the discoloration process, 80 disks of each material were fabricated, each measuring 5 mm in diameter and 2 mm in thickness. These disks were then measured for lightness*red/green*blue/yellow (L*a*b*) values. Around 10 samples from each subgroup were then submerged in each of the four staining solutions. Analysis of discoloration levels was done at baseline and 48 hours after immersion in the staining solution. Each specimen's staining effect was evaluated using a spectrophotometer.Each specimen's L*a*b* values were measured three times by placing it on the measurement head. The internal energy (ΔE) unit, which expresses resistance to the staining effect, was derived using each specimen's L*a*b* values. All the tested materials showed a color change. However, giomer showed greater ΔE values compared to nanohybrid composite and ormocer. Of all the immersion media used, Boost samples resulted in the highest color change, followed by Complan, Pediasure, and milk. Out of the three restorative materials used in the study, ormocer showed more resistance to color change than nanohybrid composite and giomer with all the tested media. Ponnala SL, Punithavathy R, Birapu UKC, et al. An In Vitro Staining Effect of Different Children's Health Drinks on Esthetic Restorative Materials. Int J Clin Pediatr Dent 2023;16(2):211-217.

Molecular engineering of fluorescence probe for real-time non-destructive visual screening of meat freshness.

Spoiled meat poses a great challenge to food security and human health, which should be addressed by the early monitoring and warning of the meat freshness. We herein exploited a molecular engineering strategy to construct a set of fluorescence probes (PTPY, PTAC, and PTCN) with phenothiazine as fluorophore and cyanovinyl as recognition site for the facile and efficient monitoring of meat freshness. These probes produce an obvious fluorescence color transition from dark red to bright cyan in response to cadaverine (Cad) through the nucleophilic addition/elimination reaction. The sensing performances were elaborately improved to achieve quick response (16s), low detection limit (LOD=3.9nM), and high contrast fluorescence color change by enhancing the electron-withdrawing strength of cyanovinyl moiety. Furthermore, PTCN test strips were fabricated for portable and naked-eye detection of Cad vapor with fluorescence color change from crimson to cyan, and accurate determination of Cad vapor level with RGB color (red, green, blue) mode analysis. The test strips were employed to detect the freshness of real beef samples, and demonstrated a good capability of non-destructive, non-contact and visual screening meat freshness on site.

COLOR CHANGES OF 3D PRINTED AND CONVENTIONAL DENTAL RESINS FOR REMOVABLE PROSTHODONTICS AFTER IMMERSION IN DIFFERENT STAINING AGENTS

Introduction: The discoloration of the denture base resins is one of the shortcomings of this type of dental materials, and it could be determined through various visual and instrumental methods. The aim of the current study was to evaluate the color stability of 3Dprinted and conventional denture base resins after immersion in different staining solutions. Materials and methods: A total of 200specimens were manufactured from two types of materials: 3D printed dental resin NextDent Denture 3D+ (NextDent, 3D Systems, The Netherlands) and heat-polymerized PMMA Vertex (3D Systems, The Netherlands), which were immersed in four types of colorants - artificial saliva, coffee, red wine and coke (n = 25). For measuring the color changes (CIE-L*a*b* system) of all specimens after storage in artificial saliva for 24 h at 37 degrees C (T0), a spectrophotometer SpectroShade Micro (SpectroShade, USA) was used. After seven days (T1), 14 days (T2) and 21 days (T3), the mean ∆E values were calculated and compared by Bonferonni post-hoc test. The data were processed using thestatistical software SPSS 26. The level of significance forrejecting the null hypothesis was fixed at p&lt;0,05. Results: The values for ΔE were investigated, and the interactions between the type of material,the immersion time and the different staining solutions were statistically significant. The highest mean for ∆E was evaluated for both types of dental resin in red wine. Respectively, 3D printed specimens in artificial saliva were with the lowest mean. Conclusions: The 3D printed denture base resin demonstrated better color stability than the conventional acrylic materials. The staining effect correlated with the immersion time, with the red wine and coke being with the most chromogenic impact and the period with the highest color changes being 21 days.There was a significant interaction between theselected time periods and the type of staining agent, as both types of dental materials showedchanges in color stability at T1 compared to T3.

Effect of Combining Minimal Invasive Modalities on Treating Mild Dental Fluorosis: An In vivo Study

BACKGROUND: Fluorosis is intrinsic tooth discoloration which compromises esthetics depending on its severity. AIM: The aim of the study was to assess the efficiency of various treatment modalities in esthetic improvement of mild fluorosed teeth. MATERIALS AND METHODS: Four patients with 48 mild fluorosed teeth were randomly assigned to four treatment modalities (n = 12). The modalities included M1: power bleaching, M2: microabrasion and power bleaching, M3: power bleaching and resin infiltration and M4: microabrasion, power bleaching and resin infiltration. Color parameters (L, a, b) and visible color change (ΔE) were measured by spectrophotometer (VITA Easyshade®) at baseline, immediately after the treatment, after 3, 6, and 9 months. STATISTICAL ANALYSIS: Two-way ANOVA was applied to test the interaction between different variables. ANOVA repeated measures were followed by Duncan multiple range tests (DMRTs) to compare between groups. RESULTS: All the treatment modalities showed significant color change (ΔE) at all-time points compared to baseline. The highest color change was recorded in the resin infiltration treatment modalities compared to the other treatment modalities. Bleaching alone had the lowest change. CONCLUSION: Resin infiltration treatment modalities were more effective in the esthetic improvement of dental fluorosis compared to either power bleaching alone or combination of microabrasion and power bleaching.

The effect of different staining solutions on the color stability of temporary crown materials.

The esthetic expectations of patients are increasing by the day. That is why it is important to minimize the color changes in the oral cavity in both the temporary and permanent restorations. This study was carried out to compare the time-dependent color changes of polished and unpolished temporary crown materials prepared by different methods in various solutions. Half of the two different temporary restoration materials prepared with a diameter of 10 mm and a thickness of 2 mm were polished, and half were not polished. The ΔE* values of the samples kept in various solutions were recorded. Data were statistically evaluated by using variance analysis (ANOVA) and a Tukey HSD multiple comparison test. It was determined that the material type, the solution, the interaction between the material types and the surface treatment, and the interaction between the surface treatment and the solution were statistically significant for color change (p < 0.001). The most significant color change in the inter-material evaluation was observed in chemically polymerized polymethyl methacrylate. In the evaluation between beverages, the highest color change was found in sugared coffee, and the lesser color change was observed in polished samples.

Time-resolved encryption via photochromic and mechanochromic system based on silane-substituted spiropyran

With the continuous progress of forgery and decryption, the traditional static encryption technology is becoming more and more inadequate, which also strongly demands the development of multilevel anti-counterfeiting materials and advanced multi-dimensional encryption strategies and technologies. Here a new strategy to realize time-resolved encryption based on a silane-substituted spiropyran is presented, which exhibits tunable dynamic photochromic features caused by the reversible photochromic and mechanochromic properties with exceptional reversible absorption/luminescence modulation ability both in powder and crystal state. This compound shows excellent photochromic properties, including extremely rapid response time, high contrast color change, high reversibility etc. In addition, the growth of large-size needle-like single crystal by solution evaporation is helpful to further explore the mechanism of grinding discoloration of the compound. What's more, it is possible to modulate the luminescence emission and color change by simply changing the ultraviolet light stimulation time or grinding time, providing fine and adjustable time-related characteristics for the material, which can not only be used for data processing with more extended information, but also be used to construct confidential materials by time-resolved multidimensional encryption and dynamic anti-counterfeiting.

Assessment of color stability of shade less composite resin: an in-vitro study

Objective: This study aimed to assess the color stability of omnichroma composite resin after immersion in coffee, cola and iced tea. Methods: A total of 30-disc shape specimens of omnichroma, 10mm diameter and 2mm thickness, were made in a Teflon mold. The samples were washed and stored in artificial saliva for 24 hours in a 37&amp;#xb0;C incubator. The top surfaces of specimens were polished with polishing disks (Sof-lex; 3M ESPE). Samples were divided randomly into 3 groups, and each group contained 10 discs. Groups were immersed in 15 ml of 3 different storage media (cola, iced tea and black coffee). Immersion groups were stored in an incubator at 37 &amp;#xb0;C. Color assessment was carried out by VITA Easy shade 2.0 spectrophotometer color assessment device according to the CIE L*a*b*system, against a gray background to measure baseline records for the samples. After 4 weeks, a second record was taken for the samples after they were gently rinsed with distilled water and dried. The experimental data were statistically evaluated using the Wilcoxon sign rank test with a significance level &amp;lt; 0.05%. Results: The highest color change was reported with coffee (ΔE=20.16) followed by cola (ΔE=19.6) and iced tea (ΔE=4.75). Conclusion: All assessed drinks resulted in discoloration of the shade less composite resin material above the clinically acceptable level (ΔE&amp;gt;3.3) after 30 days of immersion. Coffee has the highest staining among the three drinks, followed by cola, and then iced tea.

Effects of Different Adhesive Systems and Orthodontic Bracket Material on Enamel Surface Discoloration: An In Vitro Study

The aim of this in vitro study was to assess the effect of the type of orthodontic brackets and adhesive systems on enamel discoloration. The baseline color of the buccal surfaces of 50 extracted human premolars was recorded using a spectrophotometer according to the CIE Lab system. The teeth were randomly divided into five groups according to the bracket type and adhesive system used: Group A: metal brackets + a Three-step etch and rinse adhesive (E&amp;R); Group B: metal brackets + a two-step self-adhesive adhesive (SE); Group C: ceramic brackets + (E&amp;R); Group D: ceramic brackets + (SE); Group E: no bracket bonding, serving as a control. All teeth were thermocycled, the brackets were debonded, and the enamel surfaces were finished and polished. The tooth color was then re-assessed, and the change in color (∆E*) was calculated. Pairwise comparisons revealed significant differences in favor of ceramic brackets (ΔE = 3.77 ± 3.60; p = 0.009) and (E&amp;R) (ΔE= 3.52 ± 2.45; p = 0.008). A significant difference was found among the different groups, with group C having the least change in color (ΔE = 2.00 ± 0.89) and group B having the highest (ΔE = 8.42 ± 5.66). Both the type of orthodontic bracket and adhesive system influenced tooth color change. The teeth bonded with ceramic and E&amp;R had the least effect on color changes, whereas teeth bonded with metal and SE showed the highest color changes after debonding.

Coronal discoloration induced by calcium silicate-based cements used in full pulpotomy in mature permanent molars: a randomized clinical trial.

This study aimed to randomly compare in vivo coronal discoloration at 6 and 12months after full pulpotomy in mature permanent molars using MTA, Biodentine, and TotalFill and to investigate the effect of variables such as remaining buccal wall thickness and time to achieve hemostasis. One hundred eight teeth that met the inclusion criteria received full pulpotomy and were randomly divided into 3 groups via a block randomization technique according to the calcium silicate cement (CSC): ProRoot WMTA, TotalFill, or Biodentine. Assessment of tooth color was carried out using a spectrophotometric device (VITA Easyshade Compact) after composite placement (T0), at 6- and 12-month follow-up. Buccal wall thickness and time to hemostasis were recorded. The primary outcome measure (color change ΔE) was calculated, and the results were analyzed by three-way ANOVA and crosstabulations in relation to material type and effect of variables. Four cases were excluded after pulpotomy failure; 81 teeth were evaluated at 6months and 95 teeth at 12months. All CSCs caused tooth discoloration (defined as ΔE > 3.7); MTA significantly caused the highest color change at 6- and 12-month follow-up (76% (19/25) and 87.5% (28/32), respectively) compared to Biodentine (41% (9/22), 48% (13/27)) and TotalFill (44% (15/34), 53% (19/53)) (p = 0.022, p = 0.002), while no significant difference was found between the Biodentine and TotalFill groups (p = 0.813, p = 0.8). Buccal wall thickness (above or below 2.7mm) had a significant effect on the degree of discoloration (p = 0.004). The 3 CSCs caused tooth discoloration based on the threshold of ΔE > 3; the remaining buccal wall thickness was a significant factor. The use of Biodentine and TotalFill instead of MTA is encouraged to minimize discoloration. While experimental studies report coronal discoloration after CSCs use, clinical data is lacking. This study assessed discoloration using a spectrophotometric device. The use of materials with lower discoloration potential in pulpotomy is encouraged. The study was registered with clinical trial registration number: NCT04346849 on 14.4.2020.

Characterization and Evaluation of Water-Based Ecological Paint for Protection of Wood Materials Coated Using Dipping Technique

The aim of this study was to characterize and evaluate the performance of two wood species, pine (Pinus sylvestris L.) and spruce (Picea abies Karst.) used for wooden furniture in outdoor coated with a water based ecological paint and subjected to artificial weathering. Another task of this research was to investigate the potential of the application of paint using dipping method in alternative to traditional brush or spraying coating application methods, since, if wood samples are grouped in stacks, the processing time can be reduced, compared to samples painted singularly. From the analysis of the dipping parameters, such as time and paint concentrations, more practical and specific knowledge was obtained regarding this painting method.From the characterization of the painted samples and from the measurements of color changes during artificial weathering it was observed that coated wood surfaces have similar optical properties also in case of different dipping times, although the type of wood could affect the performance of final product during artificial weathering test as in case of spruce wood samples, specifically those prepared with the shortest dipping time: for these samples a lower resistance to weathering and higher color changes were observed.

Clinical Evaluation of Different Minimal Invasive Treatment Modalities of Mild to Moderate Dental Fluorosis Using an Intra-oral Spectrophotometer

BACKGROUND: Various treatment modalities are available to improve esthetics of fluorosed teeth based on its severity. AIM: The aim of the study was to evaluate the clinical performance of different minimal invasive treatment protocols on mild to moderate fluorosed teeth. METHODS AND MATERIALS: Before the interventions, tooth color coordinates L, a and b were recorded for 160 fluorosed teeth by Vita Easyshade V. Participants were randomly allocated in eight treatment protocols with 20 teeth (n = 20) included in each protocol. Protocol one (P1) Opalescence boost PF 40%. Protocol two (P2) Opalustre. Protocol three (P3) MI-Paste Plus. In protocol four (P4) teeth were treated with Opalustre followed by Opalescence boost PF 40%. In protocol five (P5) Opalescence boost PF 40% was applied followed by MI-Paste Plus, while in protocol six (P6) Opalustre was applied followed by MI-Paste Plus whereas protocol seven (P7) teeth were treated with Opalustre, followed by Opalescence boost PF 40% and finally MI-Paste Plus. Protocol eight (P8) control. All teeth were evaluated immediately for color change (ΔE) after treatment (T1), after 14 days (T2), after 3 months (T3) and after 6 months (T4). Color change (ΔE) was calculated from ΔL, Δa, and Δb recorded at each evaluation time point. STATISTICAL ANALYSIS: Two-way ANOVA was applied to test the interaction between different variables. ANOVA repeated measures were followed by Duncan multiple range tests (DMRTs) to compare between groups. RESULTS: In accordance to time, all treatment protocols showed significant color change can be recognized by unexperienced eye (ΔE ≥ 3.7). Immediately after application (T1), the highest color change (ΔE) was recorded in P7. While at 14 days and 3 months follow ups, color change in P4 exceeded P7. After 6 months the highest ΔE was recorded in both P4 and P7 with no significant difference between them. Meanwhile, in Accordance to treatment Protocol, The highest color change was recorded at 3 months (T3) in all treatment protocols. These records were preserved at 6 months follow-up (T4) for all treatment protocols except P1 and P3. CONCLUSION: Combined treatment protocols of Opalustre and Opalescence boost PF 40% have the highest effect on ΔE regardless of using MI-Paste Plus. MI-Paste Plus provides stability of ΔE results at 6 months’ follow-up.

The effects of thermosonication on quality parameters of cashew apple nectar: An optimization study for processing conditions

Thermosonication is an alternative treatment to process juices avoiding the thermal degradations promoted by conventional heat treatments. Therefore, the aim was to determine the optimal parameters of thermosonication to treat cloudy cashew nectar to inactivate polyphenol oxidase-(PPO), while promoting the maintenance of some bioactive compounds. The effects of ultrasound energy density-(UED) and temperature on PPO inactivation and some quality properties such as total phenolic-(TP), ascorbic acid-(AA) and color difference-(ΔE*) were determined and revealed by mathematical models. The increase in only one parameter (temperature or UED) caused a rise in PPO inactivation, while the other quality properties were constant. The same concentration of TP was obtained (426 mg/L) with high UED - low temperature (25 °C–595 J/g) or low UED – high temperature (121 J/g–57 °C). The highest levels of PPO inactivation, TP and AA content (1171 mg/L) were provided when treatment of approximately 350 J/g UED was performed at a high temperature (65 °C). An increase in temperature affected ΔE* more than UED, the highest color change was observed at 598 J/g and 45 °C. Thus, the optimal parameters of thermosonication were determined as 300 J/g and 60 °C.

Comparison of Stain Effects of Nicotine and Beverages on Different Cad-Cam Materials

Purpose: This study aimed to compare the effect of smoking cigarettes and drinking beverages and also polishing procedures on the discoloration of CAD/CAM materials. Materials and Methods: Resin nanoceramic (Lava Ultimate-RN), feldspar ceramic (CEREC Blocs Ceramics-FC) and lithium disilicate glass-ceramic (IPS e.max® CAD-LDC) specimens (5X5 X2 mm) were used for this study. Initially, baseline surface roughness (Ra) and color values (L*, a*, b*) of the specimens were measured with profilometer and chroma meter. Then the specimens were exposure nicotine, coffee and red wine. The first discoloration values of each specimen were measured. Then, all of the specimens were subjected to re-polishing procedures. Than, the surface roughness and color values of each specimen were measured. The specimens were subjected to the same staining process again. After exposure of the specimens to the staining agents, the second staining value was measured. Two-way analysis of variance (ANOVA) was used for normally distributed groups, and the Kruskal-Wallis test was used for non-normally distributed groups. Results: Statistically significant ΔE* values were observed for RN (8.26±1.55) and FC (7.69±1.52) for nicotine in the first staining group. The maximum total color changes were observed in the nicotine group for all of the material specimens. Nicotine caused the highest color changes on the test materials than coffee and wine. Surface roughness did not show a statistically significant difference based on the staining agents for any of the materials within a group (p&amp;lt;0.05). Conclusions: It was observed that nicotine staining is far stronger than beverage staining.

Comparison of Stain Effects of Nicotine and Beverages on Different Cad-Cam Materials

Purpose: This study aimed to compare the effect of smoking cigarettes and drinking beverages and also polishing procedures on the discoloration of CAD/CAM materials. Materials and Methods: Resin nanoceramic (Lava Ultimate-RN), feldspar ceramic (CEREC Blocs Ceramics-FC) and lithium disilicate glass-ceramic (IPS e.max® CAD-LDC) specimens (5X5 X2 mm) were used for this study. Initially, baseline surface roughness (Ra) and color values (L*, a*, b*) of the specimens were measured with profilometer and chroma meter. Then the specimens were exposure nicotine, coffee and red wine. The first discoloration values of each specimen were measured. Then, all of the specimens were subjected to re-polishing procedures. Than, the surface roughness and color values of each specimen were measured. The specimens were subjected to the same staining process again. After exposure of the specimens to the staining agents, the second staining value was measured. Two-way analysis of variance (ANOVA) was used for normally distributed groups, and the Kruskal-Wallis test was used for non-normally distributed groups. Results: Statistically significant ΔE* values were observed for RN (8.26±1.55) and FC (7.69±1.52) for nicotine in the first staining group. The maximum total color changes were observed in the nicotine group for all of the material specimens. Nicotine caused the highest color changes on the test materials than coffee and wine. Surface roughness did not show a statistically significant difference based on the staining agents for any of the materials within a group (p&amp;lt;0.05). Conclusions: It was observed that nicotine staining is far stronger than beverage staining.

THE CHANGES IN THE SURFACE OF FLAT PRESSED WOOD-PLASTIC COMPOSITES EXPOSED TO ARTIFICIAL WEATHERING

In this study, the wood flour content's effect on the weathering performance of flat pressed WPC was investigated. The high density polyethylene was reinforced with four different wood flour content (10%, 30%, 50%, 70%). The weathering performance of WPC was determinedby the 400 h of artificial weathering test. According to the results, the color change is inevitable aslong as the wood flour is used as filler. Surprisingly, the highest color change was obtained from WPC containing 30% WF, contrary to 70% of wood flour. Similarly, the whiteness of thesurface of WPC increased with exposure time. The photooxidation resulted in the chain scission and shorter molecules, which were observed by ATR-FTIR analysis. The changes in the intensity of characteristic polymer (2914 cm-1and 2846 cm-1) and wood peaks (1510 cm-1and 1027 cm-1) exhibited the photodegradation on WPCs' surface, which resulted in color change. Moreover, the light microscopy investigation showed surface degradation. Theextensive weathering conditions causedsurface cracks and surface roughness. The visual appearance of WPCs also demonstrated how to change the surface character of WPC during the400 h of artificial weathering. In conclusion, the increase inthe wood content increased theintensity of degradation.

Effect of simulated brushing and disinfection on the surface roughness and color stability of CAD-CAM denture base materials

PurposeTo evaluate the effect of simulated brushing and chemical disinfection on the surface roughness and color stability of CAD-CAM denture base materials and to compare with those of a heat-cured denture base material. Material and methodsDisk-shaped specimens (Ø 10mm × 2 mm) were prepared from 3 CAD-CAM denture base resins (AvaDent, Ava; Merz M-PM, Merz; Polident d.o.o, Poli) and a heat-cured polymethylmethacrylate resin (Promolux, Conv) (n = 30). After polishing, baseline surface roughness (Ra) and color coordinates were measured. The measurements were repeated after 20000 cycles of simulated brushing, and the specimens were divided into 3 groups according to disinfection protocol (distilled water, 1% sodium hypochlorite (NaOCl), and effervescent tablet) (n = 10). After 9 cleaning cycles over a period of 20 days, Ra and color coordinates were remeasured. Color differences (ΔE00) were calculated by using CIEDE2000 formula. One-way analysis of variance (ANOVA) and pairwise t-tests were used to analyze Ra and ΔE00 data, while repeated measures ANOVA test was used to compare baseline, after brush, and after disinfection Ra values (α = 0.05). ResultsBrushing did not affect the Ra values of tested materials (P ≥ .08). Both before and after brushing, Merz and Conv had higher Ra values than Poli and Ava (P < .001). Among disinfectants, effervescent tablet led to the lowest Ra for Merz (P = .003) and the highest Ra for Poli (P ≤ .039). Only NaOCl resulted in significant differences among the Ra of materials (P < .001), as Merz and Conv had higher Ra values than Poli (P ≤ .002). Repeated measures ANOVA revealed that effervescent tablet disinfection of Merz led to lower Ra values than those of baseline and after brushing (P ≤ .042). After brushing, Ava and Conv had higher ΔE00 values compared with Merz and Poli (P ≤ .015). When compared with other disinfection protocols, effervescent tablet led to higher ΔE00 values for Merz and Poli (P < .001). Significant differences were observed among materials when NaOCl was used; Conv had higher ΔE00 values than Ava and Merz (P = .004). ConclusionsBrushing did not increase the surface roughness of materials. Disinfection protocol's effect on the surface roughness varied. The effect of brushing on the color of materials varied; color of Ava and Conv was affected from brushing more than the other materials. Color stability of materials varied depending on the disinfection protocol. Effervescent tablet caused higher color change with Merz and Poli compared with other disinfectants. NaOCl led to small color change for Poli, Ava, and Merz materials.

Effects of Disinfection Methods on the Color Stability of Precolored and Hand-Colored Maxillofacial Silicone: An In Vitro Study.

Maxillofacial prostheses are used in rehabilitation of patients with facial defects. Typically, these prostheses are fabricated with medical grade silicone and are tinted corresponding to the patients' natural skin color. However, exposure to environment and disinfectants can result in color changes. This study aimed to evaluate the effects of four different disinfection methods on the color stability of precolored and hand-colored maxillofacial silicones. Forty specimens each of precolored and hand-colored silicone were prepared. The specimens were randomly divided into eight groups (n = 10) and cleansed with four different disinfection methods. Disinfection was carried out six times/day for 60 days, simulating once-a-day disinfection for a year. Color evaluation was carried out at day 0 and day 60 using a UV-vis spectrophotometer. Color alterations were calculated by the CIE L∗a∗b∗ system. Data were analyzed by two-way ANOVA with post hoc Tukey HSD and t-tests (α = 0.05). Disinfectants can affect the color stability of maxillofacial silicone. In our study, chlorhexidine solution and liquid soap resulted in the highest color change. Precolored silicone showed higher color stability than its hand-colored counterpart.