Influence of Surface Treatment on the Color Stability and Microhardness of Two Nanohybrid Enamel Shade Resin Composites: An In-Vitro Study.

Objective:The aim of this study was to evaluate the effect of finishing time and polishing time on surface roughness and microhardness of nanofilled and hybrid resin composites.Materials and Methods:Hundred disk composite specimens from micro hybrid composite and nanohybrid composite were prepared, 50 for each type of composite. The specimens were divided into five groups according to the time of finishing and polishing (immediate, 15 min, 24 h and dry). Composite under the Mylar strip without finishing and polishing was taken as the control group. Surface roughness was measured with environmental scanning electronic microscope (ESEM) and microhardness was determined using Vickers Microhardness Tester. Data collected were statistically analyzed by t-test and one-way analysis of variance (ANOVA) followed by Turkey's post hoc test.Results:Smooth surface with low hardness was obtained for the group under Mylar strip without finishing and polishing. The highest roughness was recorded for delayed finishing and polishing for both composites. Immediate finishing and polishing increased the surface hardness more than that in the control group in both types of composites. Dry finishing reduced the hardness significantly for micro hybrid composite, but resulted in the highest surface hardness for nanofilled composite.Conclusion:Immediate finishing and polishing under coolant resulted in the best surface smoothness and hardness values in micro hybrid composite; however, immediate dry finishing and polishing gave the best smoothness and hardness values in nanohybrid composite.

Aim: To investigate the impact of different inhibitory techniques on the thickness of oxygen-inhibited layer (OIL) and diametral tensile strength (DTS) value in various types of nanofilled composite resins. Materials and Methods: Thirty-six nanofilled composite resins specimens, consisting of packable, flowable, high-viscosity bulk-fill (HVBF), low-viscosity bulk-fill (LVBF), shaped as half disk (diameter: 6 mm and height 3 mm) and randomly allocated to three groups (n = 3): with Mylar strip, glycerin application, and without OIL inhibitors. OIL thickness was observed with an optical microscope. Furthermore, 60 specimens of composite resins were incrementally created in disk-shaped molds (diameter: 6 mm, height: 1.5 mm × 2 mm). DTS measurements were carried out using a universal testing machine. Data were statistically analyzed using a two-way analysis of variance (ANOVA) test and Pearson’s correlation test (P < 0.05). Results: OIL inhibitor techniques (Mylar strip and glycerin) significantly affected OIL formation across various types of nanofilled composite resins (P < 0.05). Changes were also observed in how these techniques influenced DTS values. Correlation analysis indicated a positive relationship between OIL thickness and DTS value. Conclusions: Application of Mylar strip and glycerin reduced OIL thickness and DTS values in packable, flowable, HVBF, LVBF nanofilled composite resins. Glycerin proved to be more effective than Mylar strips in reducing OIL thickness, which is reflected in the DTS values of nanofilled composite resins. Greater OIL layer thickness on the outermost layer of the nanofilled composite resin correlated with a higher DTS value.

Denture base materials: An in vitro evaluation of the mechanical and color properties

Surface microhardness and color stability of dental restorative material should be sustained throughout its functional lifetime to maintain the esthetic quality of the restoration. However, the frequent application of mouthwash may affect their surface microhardness and color stability. The aim of this study was to evaluate the effects of different types of mouthwashes with different contents on surface microhardness and color stability of dental nanohybrid resin-based composite. Disc specimens of nanohybrid resin composite (Luna Nano-Hybrid Composite) were prepared according to manufacturing instructions; specimens were incubated for 24 h in three types of mouthwash (Chlorohexidine, Listerine Green Tea, and Colgate Optic White Whitening Mouthwash). Artificial saliva was used as a control group. Surface microhardness was evaluated using Vickers microhardness device. Color stability after and before immersion in the different mouthwashes was evaluated using extra-oral spectrophotometer; the values of color change (ΔE00) were subsequently calculated. Data were analyzed using one-way ANOVA and post hoc test (p ≤ 0.05). There was no significant difference between microhardness of resin composite immersed in artificial saliva, CHX, and Green Tea mouthwashes (78.5, 78.4, and 73.5, respectively) (p ≥ 0.1), while the bleaching mouthwash led to the lowest microhardness of resin composite, with significant difference compared to the three previous immersion media (p = 0.002). Moreover, there were significant differences in the color changes (ΔE00) of resin composite exposed to the various immersion media (p = 0.0001). The bleaching mouthwash led to a significant reduction in nanohybrid resin composite's microhardness compared to the chlorohexidine and Green Tea containing mouthwashes. The resin composite's color change was accepted in bleaching mouthwash but unaccepted in chlorohexidine and Green Tea containing mouthwashes.

Long-term color stability of composite resins is one of the most important factors influencing the clinical longevity of aesthetic restorations. This study evaluated the effect of novel reduced steps and gold standard multiple steps polishing systems of two composite resins; a nano-filled (Filtek Z350XT) versus a supra-nanofill (Palfique LX5) on their color stability after submitting to thermocycling with common beverages. Sixty disc-shaped specimens were fabricated from both composite resins ( n = 30). From each material, ten specimens acted as the control group (Mylar strip), ten specimens were polished with Sof-Lex Diamond spirals, and ten were polished with Super-Snap X-Treme discs. All the specimens were thermocycled with staining solutions. Color was measured by a spectrophotometer before and after thermocycling and color difference (ΔE*) was calculated. One-way analysis of variance followed by Tukey's post-hoc test and independent t -test ( α = 0.05) were used. A significantly highest color change was recorded for both control subgroups ( P < 0.05), and the Sof-Lex Diamond spiral showed significantly the lowest color change ( P < 0.05). Both the control and Sof-Lex Diamond spiral subgroups of Palfique LX5 produced significantly lower color change compared with subgroups of Filtek Z350 ( P < 0.05). Sof-Lex Diamond spiral polishing system provided the least color difference for both composites, while there was no significant difference between the materials when the Super-Snap X-Treme polishing system was used.

To examine the influence of the oxygen inhibited layer (OIL) on shear bond strength (SBS) to dentin and surface free energy (SFE) characteristics of different adhesive systems. Three adhesive systems were used: Scotchbond Multipurpose (SM), Clearfil SE Bond (CS), and Scotchbond Universal (SU). Resin composite was bonded to dentin surfaces to determine SBS with and without OIL of adhesives. The SFE, dispersion force (γSd), polarity force (γSp), and hydrogen bonding force (γSh) of cured adhesives with and without an OIL were measured. Two-way ANOVA and Tukey's honestly significant difference (HSD) test were used for analysis of SBS data, and one-way ANOVA and Tukey's HSD test were used for the SFE and contact angle data. The SBS of SM and CS showed no significant differences between specimens with and without the OIL. However, the SBS of SU with the OIL was significantly higher than without the OIL. The SFE, γSp, and γSh of cured adhesives with an OIL were significantly higher than those of cured adhesives without an OIL. The SFE, γSp, and γSh of SM and CS with an OIL were significantly higher than those of SU with an OIL. The results of this study indicate that the presence of an OIL with a single-step self-etching adhesive promotes higher SBS to dentin, unlike in the other types of adhesive systems. The SFE characteristics of the OIL of dental adhesives differed depending on the type of adhesive system.

This study was conducted to evaluate the effect of ceramic thickness on the surface hardness of light-cured and dual-cured resin cements. Forty disk-like specimens of the dual-cured resin cement and twenty-four specimens of the light-cured resin cement were prepared (with 6 mm diameter and 1mm thickness). The samples were light-cure d for 40 seconds through three different ceramic disks (2 mm, 3 mm and 4 mm). Control specimens from each group were directly polymerized under a Mylar strip. In the control group of the dual-cured resin cement, the cement setting was realized by chemical reaction alone. After storing dry in darkness (24 hours, 37°C), the surface hardness of the specimens was measured using the Vickers microhardness test. Data were statistically analyzed using a two-way analysis of variance (ANOVA) followed by the LSD's test (p <0.05). BisCem resin cement which had been dual-cured under the 4 mm thickness ceramic with the 4.3 Vickers hardness, showed minimum surface microhardness, while the light-cured resin cement which had been directly activated in the control group with the 51.8 Vickers hardness value exhibited the maximum surface microhardness. So, BisCem dual polymerized control specimens had significantly higher hardness values in comparison to the chemically polymerized and indirectly activated ones (p <0.001). An increase in the thickness of ceramic could decrease the hardness of the resin cement. An overlying ceramic thickness of 3 mm and above was found to adversely affect the polymerization of the LC and DC resin cement and it was considered as the clinical threshold. In addition, using only the self-cured mode in the dual-cured resin cement was not sufficient for achieving the optimum surface microhardness. Clinical significant: Adequate polymerization of resin cement is essential for the optimal mechanical properties and clinical performance. It affects by increasing the thickness of ceramic restorations.

This study aims to evaluate the color stability and related properties including water sorption and solubility of ten light-cured composite resins in different solutions. A total of 10 composite resins were BeautifilⅡ(B2) and Ceram. X One Universal (CXU), Charisma (CS), Charisma Diamond (CD), Denfil (DF), DX. Universal (DXU), Filtek Z250 (Z250), Filtek Z350 XT (Z350), FS-1 (FS), and Magnafill Putty (MP). Meanwhile, a total of 20 disk-shaped samples were fabricated and randomly divided into four groups (n=5), which were immersed in distilled water (control group), curry, coffee, and red wine for 28 days. The color (CIE L∗a∗b∗) was measured by a spectrophotometer at baseline and 1, 7, 14, 21, and 28 days after immersion, and the color differences were calculated. Water sorption and solubility values were measured ba-sed on ISO 4049: 2019. In addition, three-way ANOVA was used to evaluate the influence of resin materials, solutions, and immersion time on discoloration results, meanwhile, one-way ANOVA was used to compare the water sorption values and solubility values of different materials. All samples showed a certain degree of color change with time. Color differences were significantly influenced by materials, solutions, and immersion time (P<0.001). The color changes of the measured materials at any time point: curry>red wine>coffee>distilled water. Thus, all materials showed clinically unacceptable discoloration (ΔE>3.3) after immersing in staining curry, coffee, and red wine for 7 days. Therefore, when immersed in curry for 28 days, CS and DXU had the smallest and the largest color difference. In addition, when immersed in coffee for 28 days, FS showed the smallest color change and DXU showed the largest. Moreover, when immersed in red wine for 28 days, FS showed the smallest color change and Z350 showed the largest. Furthermore, MP and CXU had small color differences in all solutions. Meanwhile, Z350 had the highest water sorption and MP had the lowest. The solubility values of CS and CD were significantly higher than those of other materials. The color stability of light-cured composite resin is materials-depended and affected by pigment types and immersion time. Thus, MP and CXU have better color stability. MP has low water sorption.

Objective: The aim of this study was to examine how staining with coffee affects single-shade universal resin composites and a multi shade universal resin composite in terms of translucency and color stability. Method: Five different resin composites (Omnichroma, Vittra APS Unique, Zenchroma, Charisma Diamond One, and Neo Spectra ST) were used to create 50 samples (n=10). A spectrophotometer was used to record translucency parameter (TP00) and color changes ( ΔE00) at baseline and after immersion in coffee for 24 h. Color differences were calculated according to CIEDE2000. Data analysis was performed using one-way ANOVA and the paired-samples t-test. Results: After immersion of resin composite samples in coffee for 24 h the Vittra APS Unique group showed the highest ΔE00 value and the Neo Spectra ST group the lowest (P&amp;lt;0.001). At baseline, low TP00 values were observed in Neo Spectra ST and Charisma Diamond One and high TP00 values in Omnichroma and Vittra APS Unique (P&amp;lt;0.001). After being stained with coffee On day 1, low TP00 values were recorded in Neo Spectra ST and Charisma Diamond One, and high values TP00 in Omnichroma and Zenchroma (P&amp;lt;0.001). Conclusion: Short-term staining resulted in less color change in the multi shade universal resin composite than in the single-shade universal resin composites. ΔE00 and TP00 values varied between the single-shade universal resin composites Keywords: Color Stability, Multi shade Universal Resin Composite, Single-Shade Universal Resin Composite, Translucency Parameter

Dental composite resins are commonly used due to their excellent physical and mechanical properties. However, exposure to beverages like Coca-Cola, Apple juice, and Black coffee can negatively impact these materials. This study examined the effects of these drinks on the surface microhardness and surface roughness of Nanohybrid, Giomer, and Dual-Cure Bulk-fill resin composites. Seventy-two disc-shaped resin composite specimens were prepared and divided into four groups (n = 18) based on immersion liquid: Group 1 (Coca-Cola), Group 2 (Apple juice), Group 3 (Black coffee), and Group 4 (Distilled water). The composites were further categorized into NeoSpectra (Subgroup 1), Beautifil II (Subgroup 2), and Predicta (Subgroup 3). Specimens were immersed for 14 days, alternating 18 h in beverages and 6 h in distilled water daily. Microhardness was measured using a Vickers microhardness tester, and surface roughness was analyzed by atomic force microscopy. Data were assessed using one-way ANOVA and Tukey's post hoc test, with significance set at p < 0.05. All groups experienced significant decrease in microhardness and surface roughness. Coca-Cola led to the highest roughness and hardness reduction. Among composites, the Nanohybrid resin (NeoSpectra) showed the least alteration. NeoSpectra ST, a nanohybrid composite, demonstrated superior resistance to acidic beverages compared to Giomer and Bulk-fill composites. The study finds that out of three composite materials, nanohybrid composites are the most acid resistant which provides a suitable material for patients who consume acidic beverages more frequently. In this way, clinicians can use this information to help optimally increase the longevity of their restorations by selecting materials according to oral exposure levels of acids in their patients.

Objective: The aim of this in vitro study was to evaluate surface roughness and microhardness of two bulkfill resin composites after wet and dry finishing. Materials and methods: Two Types of resin composite materials SonicFill (Sonic-activated bulk-fill Nanohybrid resin composite) and X-tra fil (Bulk-fill micro- hybrid light-cured posterior resin composite) were used. Thirty samples were fabricated of each resin composite using a metal mold measuring (6mm x 4mm). Composites were applied to molds and placed between two transparent Mylar strips and pressed flat with a microscopic glass slide. A glass slab was placed on top of the upper Mylar strip and a constant pressure was applied. The samples were cured according to manufacturers’ instructions. The samples were divided into three groups (n=10). Group A: No finishing (control group), Group B: wet finishing under water coolant, and group C dry finishing. Surface roughness was evaluated using a stereomicroscope and microhardness was measured by Vicker’s hardness tester. Data were analyzed using one-way ANOVA (P 0.05. The control group showed the lowest microhardness mean values in both materials. Dry finishing showed the highest microhardness mean values among the groups (P<0.05). Conclusion: Dry finishing and polishing increased the surface roughness and microhardness of X-tra fil (microhybrid) and (nanohybrid sonic activated) Sonicfill resin composites.

The purpose of this study was to evaluate the effect of aging and fiber-reinforcement on the color stability, translucency, and microhardness of single-shade resin composites versus multi-shade resin composite. Four resin composites (Filtek Z250, Omnichroma, Vittra APS Unique, Zenchroma) were tested. Three subgroups of specimens were prepared for each of the composites: control, polyethylene fiber-reinforcement, and glass fiber-reinforcement- groups (n = 10/per group). The samples were subjected to aging for 10,000 thermal cycles. Color differences (ΔE00 ) were calculated after aging. Relative translucency parameter (RTP00 ) and microhardness values were calculated before and after aging. A two-way analysis of variance and the generalized linear model was used (p < 0.05). The lowest and highest ΔE00 values were found for Filtek Z250 (0.6 ± 0.2) and Omnichroma resin composites (1.6 ± 0.4), respectively. The ΔE00 value of the polyethylene fiber-reinforcement group (1.2 ± 0.6) was significantly higher than the ΔE00 value of the glass fiber-reinforcement group (1.0 ± 0.4, p < 0.001). The RTP00 value of the glass fiber-reinforcement group (1.92 ± 0.78) was significantly higher than the RTP00 value of the polyethylene fiber-reinforcement group (1.72 ± 0.77, p < 0.001). The highest microhardness values were found in glass fiber-reinforcement group (76.48 ± 17.07, p < 0.001). Single-shade resin composites were more translucent, had higher color change, and lower hardness than multi-shade resin composite. For relative translucency and microhardness, statistical significance was found in the material and fiber type interaction. The glass fiber-reinforcement provided higher translucency, lower color change and higher microhardness values than polyethylene fiber-reinforcement group after aging. Thermocycling had a significant impact on the color stability, translucency parameter, and microhardness of the tested resin composite materials. Single-shade resin composite materials have greater color-changing potential. The glass fiber-reinforcement optimize resin material mechanical properties and color stability more than polyethylene fiber-reinforcement.

BackgroundThe aim of this study was to investigate the mechanical properties and dentin microshear bond strength of a conventional glass ionomer cement (GIC) compared to GIC supplemented with silver nanoparticles (SNPs) at 0.1% and 0.2% (w/w).Material and MethodsSNPs were incorporated into a conventional GIC at 0.1% and 0.2% (w/w). The unmodified GIC was used as the control group. Compressive strength, flexural strength, and micro-shear bond strength (µSBS) to dentin were evaluated using a universal testing machine. Surface microhardness was determined using a Vickers microhardness tester. The data were analyzed using one-way analysis of variance (ANOVA) and Tukey’s test.ResultsGICs containing 0.1% and 0.2% (w/w) SNPs significantly improved compressive strength, surface microhardness, and dentin µSBS compared to the unmodified GIC (p<0.05). A significant increase in the flexural strength was found for the GIC containing 0.2% (w/w) SNPs (p<0.05). However, the GIC containing 0.1% (w/w) SNPs did not affect flexural strength.ConclusionsGIC supplemented with SNP is a promising material for restoration because of its improved mechanical and bond strength properties. Therefore, it may be suggested for use especially in higher stress-bearing site restorations. Key words:Glass ionomer cement, mechanical properties, micro-shear bond strength, silver nanoparticle.

Introduction Longevity and clinical success of dental restorations can be influenced by many factors during the restorative procedures. Objective This study aimed to evaluate the influence of different placement techniques on color stability and surface roughness of two resin composites. Material and method The groups of specimens (n=10) were divided according to resin composite (FiltekTM Z250 XT and FiltekTM Z350 XT) and placement technique: Mylar strip, spatula, dry brush, modeling liquid, and surface sealant. Color stability and surface roughness were accessed using a spectrophotometer (CIELab color space) and a rugosimeter (standard cutoff of 0.8 mm), respectively, after water storage. Subsequently, the specimens were immersed in coffee for 48 h and final color was measured. The data were analyzed using ANOVA and the Tukey’s post hoc test (α=5%) and the correlation between surface roughness (Ra) and color change (∆Eab) was assessed using the Pearson’s correlation coefficient. Result The different placement techniques influenced Ra and ∆Eab on both resin composites. The groups treated with surface sealant showed greater difference in ∆Eab for both resin composites. The FiltekTM Z250 XT resin showed greater color stability compared with the FiltekTM Z350 XT resin regardless of the placement technique used. Ra of each placement technique was similar among the resin composites except for the FiltekTM Z350 XT modeling liquid group, which presented lower Ra values compared with those of FiltekTM Z250 XT. A correlation between Ra and staining was identified (p=0.268). Conclusion Color stability and Ra are influenced by different placement techniques.

This study aimed to evaluate the effects of different concentrations of astaxanthin and Bidens Pilosa compound feed additives on the color and hypoxia tolerance of cherry shrimp (Neocaridina davidi var. red). Color parameters were assessed using CIELAB color space, and differential gene expression related to color and stress was analyzed using reverse transcription quantitative polymerase chain reaction (RT-qPCR) to understand the gene regulatory mechanisms affecting color expression and stability. Over a 56-day rearing period, the feed additives AX100 (astaxanthin 100 mg/kg) and AX100+BP (astaxanthin 100 mg/kg + B. pilosa 5 g/kg) significantly reduced the color difference values compared to the standard sample (ΔE*ab), indicating notable color boosting effects. This included a reduction in lightness (L*), a decrease in color hue angle (h*) with AX100, and an increase in redness (a*) and chroma (C*) with AX100+BP. We further designed 22 color-related gene primers, 16 of which amplified the target fragment. Six gene sets exhibited significant differences among all feed treatment groups and were correlated with color expression. After 9 hours of hypoxic stress, body color remained stable in the feed additive groups, especially in the AX100 + BP and AX200 + BP (astaxanthin 200 mg/kg + B. pilosa 5 g/kg) groups, with color differences before and after hypoxic stress remaining below the discernible threshold of the human eye, indicating optimal color stability. Additionally, the CAT gene, among the stress-related genes that successfully amplified, showed significant differences among feed treatment groups and correlated with color stability based on color difference values. In conclusion, the composite addition of 100 mg/kg astaxanthin and 5 g/kg Bidens pilosa (AX100 + BP) was identified as the most effective treatment. This formulation significantly enhanced cherry shrimp color, evidenced by improved parameters such as decreased lightness and increased redness. Moreover, AX100 + BP demonstrated superior color stability under hypoxic conditions, with ΔE*ab values remaining below the discernible threshold of the human eye, highlighting its potential for maintaining optimal color during transportation. Offering a basis for enhancing the commercial value and reducing the sale risks of cherry shrimp.