Effect of Light-Curing Modes on the Color Stability of Resin-Based Restoration Materials

This in vitro study aimed to evaluate the effect of simulated gastric fluid (SGF) and an alginate-based antacid on the surface roughness and color stability of two additively manufactured (AM) and one subtractively manufactured (SM) resin-based restorative materials. A total of 168 disc-shaped specimens (10 × 2 mm) were fabricated from two AM resin composites (Bego VarseoSmile TriniQ [AM-VS] and Saremco Crowntec [AM-C]) and one SM nano-ceramic hybrid (Voco Grandio blocs [SM-V]). Specimens were distributed into seven subgroups (n = 8) based on immersion media: distilled water (control); SGF mixed with artificial saliva (AS) at ratios of 1:1, 1:3, and 1:5; and the same mixtures with 10% alginate-based antacid (Gaviscon®). All solutions were refreshed daily and maintained at 37 °C with gentle agitation for 48 h. Surface roughness (Ra) was measured with a contact profilometer, and color stability (ΔE₀₀) was assessed with a spectrophotometer. Data were analyzed using mixed-model ANOVA and post hoc tests (α = 0.05). Immersion in SGF + AS increased ΔE₀₀ and Ra values in all materials compared with distilled water (p<.001). The highest color change was observed in AM-C at SGF + AS (1:5) (1.87 ± 0.30), whereas SM-V showed the lowest ΔE₀₀ values (1.55 ± 0.04). Surface roughness increased under acidic conditions, with AM-C exhibiting the highest Ra values (1.30 ± 0.02 μm). The alginate-based antacid significantly reduced Ra values for all materials and reduced ΔE₀₀ values in AM-C (1:3 and 1:5) and AM-VS (1:5) (p<.05), with selected antacid-containing subgroups showing values approaching those of the control. Simulated gastric fluid compromised the surface integrity and color stability of CAD/CAM resin-based restorative materials, with material-dependent differences. The addition of an alginate-based antacid mitigated these effects under selected experimental conditions, suggesting a potential protective role against acid-induced degradation.

Long-term aesthetic success in dentistry largely depends on the color stability of restorative materials. This study investigated the color changes (ΔE00) of resin nanoceramic and lithium disilicate ceramic restorative materials used in computer-aided design and computer-aided manufacturing (CAD/CAM) systems following beverage immersion and after repolishing. One hundred specimens were prepared from lithium disilicate (Initial LiSi Block) and resin nanoceramic (Cerasmart), and polished. The specimens were divided into ten groups according to material and beverage type (n = 10) and immersed in distilled water, cola, tea, coffee, and turnip juice at 37 °C for 3 months. Color values were recorded at baseline, 1 week, 1 month, and 3 months, and after repolishing. ∆E00 values were calculated using the CIEDE2000 color difference formula. Data were analyzed using three-way repeated measures ANOVA and post hoc Tukey and Bonferroni tests (α = 0.05). Material type, beverage type, and immersion time significantly affected color stability (p < 0.05). The highest ∆E00 observed in the resin nanoceramic-tea group at 3 months (ΔE00 = 11.39 ± 1.76). Lithium disilicate demonstrated better color stability. After repolishing, all ΔE00 values were below the clinically acceptable limit (ΔE00 ≤ 1.8). Repolishing may help maintain the long-term aesthetic success of dental restorations in the oral environment.

ObjectivesThe objective of this study was to evaluate the discolouration effects of artificial saliva, granule lemon juice, coffee (without sugar), coca cola, sour cherry juice, fresh carrot juice and red wine on resin-based composite materials that are commonly used in restorative dentistry.MethodsColour of four brands of resin composites (Filtek Z 250 (3M Espe), Filtek Supreme (3M Espe), Quadrant (Cavex), Charisma (Heraeus-Kulzer)) of A2 shade was measured after one day of immersion in eight different solutions. Colour measurements were obtained by using a XL-20 Trismus Colourimeter and colour differences (ΔE) were estimated. For statistical evaluation, analysis of variance (ANOVA), Dunnett and Tukey tests were used at a significance level of 0.05.ResultsFor the four restorative materials tested, the lowest ΔE values were observed in the artificial saliva, while ΔE values were the highest in red wine group. When comparing the four different restorative materials, Filtek Supreme exhibited the least colour changes whereas Filtek Z250 was the least colour-stable.ConclusionsDental resin composites and drinking solutions were significant factors that may affect the colour stability. After immersion for one day, all materials showed visible colour changes. The red wine solution exhibited more staining than others in three groups. Filtek Supreme showed significantly the least colour change due to its nano particle sizes.

Background: Clinicians use several lubricants to reduce composite sticking to instruments and facilitate composite modeling. This study evaluated the effect of instrument lubricants on the color stability of a resin composite after one month of water storage. Methods: 60 disc-shaped specimens (2×10 mm) of Tetric N-Ceram composite were prepared using four lubricants, isopropyl alcohol 70%, Adper single bond adhesive (SB), margin bond (MB) and composite wetting resin (CW) (12 samples for each group). No lubricant was used in the control group. Color measurement was done twice, 24 hours after sample preparation and after one month of water storage. Color differences were calculated, and the data were analyzed using ANOVA and Tukey’s post hoc tests. Results: The use of single bond as instrument lubricant caused the most color change (ΔE=4.26), and the control group (no lubricant) showed the least color change (ΔE=1.77). Using composite wetting resin as an instrument lubricant resulted in lower color changes than other instrument lubricants (P&lt;0.05). Conclusion: Composite Wetting Resin used as instrument lubricant had better color stability than other lubricants. Bonding agents are not recommended for composite restorations as instrument lubricants due to the higher risk of affecting color stability. Clinicians should be aware that using instrument lubricants might influence the color properties of dental composites.

Objective: To compare the color stability and translucency of aged and unaged experimental zirconia reinforcedrice husk nanohybrid composite resin (Zr-Hybrid) with a commercialized nanofilled and a microhybrid compositeresin after immersion in four different infusion media. Material and Methods: Three groups of standardizeddisc-shaped composite resin with 80 samples per group were prepared as follow: Group 1 (Filtek-Z350-XT),Group 2 (Zmack-Comp), and Group 3 (Zr-Hybrid). Each group was further subdivided into aged (n=40) andunaged (n=40) groups. Initial color measurements were taken using a digital spectrophotometer based on CIEL*a*b* color system. Samples in aged subgroup were subjected to 2500 thermal cycles. Subsequently, all sampleswere immersed in four different types of infusion media (n=10): T1 - Distilled water, T2 - Soft drink, T3 - Teaand T4 - Coffee. After 15 days, color measurements of all samples were measured again. Data were analyzedusing two-way ANOVA followed by Bonferroni and paired sample t-tests with a significance level set at P=0.05.Results: Unaged Zr-Hybrid showed comparable color change to Zmack-Comp and Filtek-Z350-XT (P=0.181), butaged Zr-Hybrid demonstrated the lowest color change (P&lt;0.001). Zr-Hybrid exhibited the lowest translucencyvalue (P&lt;0.001), but no significant color and translucency changes (P=0.051 and P=0.069, respectively) wereobserved between unaged and aged Zr-Hybrid. Soft drink had the greatest effect (P&lt;0.001) on color change, whilecoffee showed the greatest effect (P&lt;0.001) on translucency. Conclusion: Although Zr-Hybrid showed greateropacity, it still retained its color stability and translucency after accelerated aging compared to commercializedmicrohybrid and nanofilled composite resins. All infusion media caused discoloration and affected the compositeresins’ translucency.KEYWORDSRice husk; Color stability; Composite resin; Translucency; Zirconia.

ABSTRACTBackground:The color stability of ceramic dental materials is crucial for maintaining the aesthetic outcomes of dental restorations. Staining from commonly consumed beverages can impact the appearance of these materials, potentially requiring frequent replacement or repair.Materials and Methods:Three types of ceramic materials—lithium disilicate, zirconia-reinforced lithium silicate, and feldspathic porcelain—were tested. A total of 45 disc-shaped specimens (15 for each material) were fabricated and subjected to staining solutions (coffee, tea, and red wine) for 14 days at 37°C. Color measurements were performed before and after staining using a spectrophotometer, and color differences (ΔE) were calculated based on the CIELAB color system. Statistical analysis was performed using analysis of variance and Tukey’s post-hoc test to compare the groups (P < 0.05).Results:Lithium disilicate ceramics exhibited the least color change (mean ΔE = 2.1 ± 0.5) across all staining solutions, followed by zirconia-reinforced lithium silicate (mean ΔE = 3.2 ± 0.6). Feldspathic porcelain demonstrated the highest color change (mean ΔE = 4.5 ± 0.8), particularly in red wine (mean ΔE = 5.2 ± 0.7). Statistical analysis confirmed significant differences between the groups (P < 0.05).Conclusion:Lithium disilicate ceramics exhibited superior color stability compared to zirconia-reinforced lithium silicate and feldspathic porcelain. These findings suggest that material selection plays a vital role in minimizing discoloration over time, especially in patients with high consumption of staining beverages.

This study aimed to evaluate the color stability of bulk-fill flowable resin composites with 2 difference shades at baseline and after artificial aging. Disk-shaped specimens (Ø10 × 4 mm) were fabricated from three bulk-fill flowable resin resin composites (Filtek Bulk-Fill Flow, Venus Bulk-Fill Flow, and Estelite Bulk-Fill Flow). The specimens in each bulk-fill resin composite group were divided into two subgroups (n = 10 per subgroup) with two different shades, A1 (N = 30) and A3 (N = 30), and were polymerized with light curing (800 mW/cm2/Valo LED Unit, Ultradent) and polished. The color difference between bulk-fill resin composites was evaluated at baseline and after artificial aging using a spectrophotometer (CM-700d, Konica Minolta, Tokyo, Japan) under D65 illumination. Color coordinates were measured with CIEDE2000, and color differences (∆E00) and relative translucency parameter (RTP) values were calculated. Subsequently, the comparison of color changes (∆E00) before and after thermocycling was performed using the t-test for paired samples. The bulk-fill flow resin composites evaluated in the present study were capable of mimicking important optical properties such as light transmission. All the resin composites provided acceptable color stability at baseline and after thermocycling when the color A1 was used. On the other hand, whenever the shade A3 was used, the Venus Bulk-Fill Flow demonstrated the best optical properties. There was no statistically significant difference when comparing baseline and after thermocycling in bulk-fill flowable resin composites (p > 0.05). After thermocycling, A1 bulk-fill flowable resin composites provided acceptable color stability, and all A3 bulk-fill flowable resin composites provided visible color change, except for the Venus Bulk-Fill Flow (∆E00 = 2.35). Estelite Bulk-Fill Flow displayed the best color stability (∆E00 = 2.22) between all the combinations evaluated.

8 - Composite adhesive restorative materials for dental applications

The purpose of this study is was to compare the color stability of alkasite and other restorative materials commonly used in the field of pediatric dentistry and to study a color change in response to various beverages. Test specimens of glass ionomer, resin modified glass ionomer, alkasite restorative material, and composite resin were prepared, and the color stability was measured after thermocycling. Each specimen was also subdivided into 5 groups and submerged in PBS, coffee, green tea, coke, and orange juice to analyze the color change from the original CIE &lt;i&gt;L*a*b*&lt;/i&gt; values after 7, 14, 21, and 28 days. Composite resin showed the best color stability after thermocycling, followed by alkasite restorative material, glass ionomer, and resin modified glass ionomer. Submerging in various beverages for 7 days resulted in color change in all test specimens, with alkasite restorative material showing less color change than glass ionomer but greater change than composite resin. Alkasite restorative material showed the greatest color change in coffee, followed by green tea and orange juice, but almost no change in coke and PBS even after 28 days of submersion.

Color stability of provisional resin restorative materials

The durability and patient acceptability of prosthesis can be gauged by the capacity of visible light curing lab composite resins to maintain color stability through time and use. Consequently, this study’s goal was to assess the color stability of three layering materials, incisal, dentin, and gingiva of SR Nexco lab composite, with exposure to coffee, Coca-Cola, and turmeric solution using a spectrophotometer. A total of 60 specimens (10 × 2 mm) of SR Nexco paste were prepared and were divided into three groups based on the layering material used. Five specimens of each group were immersed in staining solutions, namely, coffee, cola, and turmeric solution. Each group’s last five specimens were submerged in distilled water (control). The incubator that housed the samples was set to 37 °C. The CIE L*a*b* method was used to quantify the color differences (E) of specimens using a spectrophotometer at baseline and after two weeks of immersion. Using ANOVA testing, the average color change for each specimen was examined. Tukey tests were used for post hoc comparisons. The calculated mean color difference (ΔE) for incisal ranges from 3.73 (distilled water) to 28.70 (turmeric). The mean color difference (ΔE) for dentin ranges from 2.66 (distilled water) to 41.19 (turmeric). The mean color difference (ΔE) for gingiva ranges from 1.72 (distilled water) to 23.88 (turmeric). The results are statistically significant. The maximum color difference is noted for dentin specimens, and turmeric stains all three layering materials to a maximum. The color stability of SR Nexco paste layering materials is significantly affected by the discoloring agents used. The comparison of color change between the three layering materials of SR Nexco paste (dentin, incisal, and gingiva) is statistically not significant. Turmeric solution exhibits more discoloration followed by cola and coffee solution.

This study aimed to investigate the effects of shade, thickness, and the application of an opaquer on the masking ability and translucency of direct gingiva-colored giomer. Five shades of giomer, namely Gum-Light-Pink, Gum-Dark-Pink, Gum-Brown, Gum-Violet, and Gum-Orange, were evaluated at thicknesses of 0.5, 1.0, 1.5, and 2.0 mm. Color measurements were obtained using a spectrophotometer against white, black, and giomer backgrounds. The results were analyzed using the CIEDE2000 color-difference formula and interpreted based on the 50:50% thresholds for excellent perceptibility ( &lt; 1.1) and acceptability ( &lt; 2.8). Measurements were repeated after applying an opaquer. Acceptable masking ability was achieved at 0.5 mm for all shades. Excellent masking ability was achieved at 1.5 mm for all shades, except Gum-Brown, which required 1.0 mm. The opaquer increased masking ability in all specimens. Translucency decreased as thickness increased (p &lt; 0.0001). Gum-Brown and Gum-Light-Pink, as well as Gum-Orange and Gum-Dark-Pink, demonstrated similar translucency at 0.5, 1.0, and 1.5 mm (p &gt; 0.05). After applying the opaquer, there were no statistically significant differences in translucency among shades at 1.5 mm and 2.0 mm (p &gt; 0.05). In conclusion, increasing thickness improved masking ability but reduced translucency of gingiva-colored material. The opaquer further enhanced masking ability and reduced translucency. The clinical significance of these results are that gingiva-colored restorations mask discolored tooth defects in the pink aesthetic area with minimal 0.5 mm tooth preparation, achieving acceptable results. The addition of an opaquer enhances masking ability for excellent outcomes.

The effect of commonly used types of coffee on surface microhardness and color stability of resin-based composite restorations

The purpose of this study was to investigate the effect of mouth rinses on the color and translucency of three computer-aided design and computer-aided manufacturing (CAD-CAM) restorative materials in laminate veneer and crown thicknesses. Specimens from two different 5Y-TZP zirconia (InCoris TZI (IT), and Zirkonzahn (ZH)) and lithium disilicate (IPS e.max CAD [IC]) in two different thicknesses (0.7 mm for laminate veneer, and 1.5 mm for crown) were sectioned. All specimens were colored with an A2-shade liquid, and the baseline color values were recorded according to the CIELab system with a spectrophotometer. Each group was divided into two subgroups (n=15) according to the immersion solution: two different mouth rinses, KL (Klorhex), and LI (Listerine, cool mint) for 180 hours. The color coordinates (L*, a*, b*) of the specimens were measured before and after immersion in a mouth rinse, and TP and ΔE00 color differences were calculated by using the CIEDE2000 color difference formula. A 3-way ANOVA, Bonferroni test, and 1-sample t tests were used to analyze the data (α=0.05). The 3-way ANOVA revealed a significant interaction of material, thickness, and mouth rinse for translucency parameter and color difference (ΔE00 ) data (p < 0.001). TP decreased for both zirconia materials in laminate veneer thickness when immersed in LI mouth rinse (p < 0.05). No difference was found among the TP mean values of three materials in crown thickness after immersed in mouth rinses (p > 0.826). Both zirconia materials immersed in LI showed greater discoloration than after immersed in KL (p < 0.05). A significant difference was found in color change values among three materials for the laminate veneer thickness after immersed in LI (p < 0.001). However, all color difference values were within the clinical acceptability threshold, except for when ZH in laminate veneer thickness was immersed in LI. The color change of ZH zirconia with LI mouth rinse in laminate veneer thickness was high. For both zirconia ceramics, translucency decreased and the color was less stable in laminate veneer thickness after immersed in LI compared to the crown thickness. The results of this in vitro study suggest that long-term use of alcohol-containing mouth rinse may alter the optical properties of tested CAD-CAM materials in tested laminate veneer thickness. For color stability with the long term use of tested mouth rinses, lithium disilicate may be preferred for both types of restorations.

The aim of the current study was to evaluate the effect of polishing systems and surface sealant on the color stability and whiteness index of single-shade resin composites after staining and bleaching. Three single-shade (Omnichroma, Charisma Diamond One, Zenchroma) and one multi-shade (Filtek Z250) materials were tested. From each resin composite, 40 specimens were prepared. The specimens were divided into 4 subgroups (n = 10) according to the surface treatments: 1-step polishing, 1-step + Biscover LV, 2-step polishing, and 2-step polishing + Biscover LV. Color differences (ΔE00) were calculated after being immersed in the coffee solution for 12 days. After the staining, the specimens were immersed in a whitening mouthrinse (Crest-3D White) for 12 hours. Whiteness index differences (∆WID = WID after staining - WID after bleaching) values were recorded. The generalized linear model was used for analysis (p < 0.05). The lowest and highest ΔE00 values were found for Zenchroma and Charisma Diamond One respectively. Sealed groups indicated higher ΔE00 values than nonsealed groups with significant differences (p = 0.008). The lowest and highest ΔWID values were found for Zenchroma and Charisma Diamond One respectively. Sealed groups indicated lower ΔWID values than nonsealed groups with significant differences (p = 0.022). The use of surface sealant increased the discoloration and showed less whiteness change in resin materials. When the 1-step was compared with the 2-step polishing, the effects on the color stability and whiteness index values of the resin materials were similar.