The role of interface distance and underlying substrate on the color adjustment potential of single-shade composites

At-Home and In-Office Bleaching Protocols on the Color Match of Restorations Made With Single-Shade Composites

OBJECTIVE

This study evaluated the color match of restorations made with single-shade composites following two protocols of tooth bleaching.

MATERIALS AND METHODS

Cavities in the cervical third of bovine crowns were restored using single-shade composites (Omnichroma or Vittra Unique) or a multi-shade composite restoration strategy (Filtek Z350 XT). The color of both the restoration and the middle third of the unrestored tooth were recorded. The Whiteness Index for Dentistry (WID) and color differences (ΔE 00) between the two areas were calculated. Specimens underwent bleaching using in-office or at-home protocols, and color evaluations were repeated at 24 h, 7 days, and 14 days post-bleaching. Data were analyzed using MANOVA and repeated measures ANOVA.

RESULTS

Bleaching protocols did not significantly affect WID or ΔE 00 values. The highest WID values were observed for Vittra Unique, and the lowest for Filtek Z350 XT. Tooth bleaching did not affect ΔE 00 values for restorations made with the multi-shade strategy, but it resulted in a reduction for those made with the single-shade strategy, regardless of the composite brand.

CONCLUSION

Tooth bleaching protocols differentially affected the color match of restorations made using single-shade composites compared to multi-shade restorations.

CLINICAL RELEVANCE

Tooth bleaching protocols have a limited effect on the color of composites but can influence the color match between the restoration and the surrounding enamel. Specifically, color mismatches tend to decrease for lighter materials, such as single-shade composites, after tooth bleaching, improving the overall esthetic integration of the restoration with the natural tooth structure.

Color matching and translucency of single-shade resin composites: effects of restoration thickness, background shade, and aging

BACKGROUND

Achieving a seamless color match in resin composite restorations remains a significant clinical challenge due to variations in tooth structure and background shades. The aim of this in vitro study was to assess the effect of background shade, thermal aging, and composite thickness on color matching and translucency of three single-shade resin composites.

METHODS

A total of 72 resin composite disks (12 mm diameter) were fabricated using three single-shade composites -Omnichroma (OMN), Charisma Diamond ONE (CDO), and Charisma Topaz ONE (CTO)- in two thicknesses (1.5 and 3 mm), resulting in six groups (n = 12 per group). Subsequently, three background disks were prepared from Estelite Sigma Quick in shades A1, A3, and B1, and the 72 composite disks were positioned on these background disks to form a two-layer assembly for evaluation. The L*, a*, and b* variables before and after thermocycling (10,000 cycles) were recorded and blending effect (BE) was calculated. The translucency was evaluated by using white and black backgrounds. The data were analyzed by Kolmogorov-Smirnov, ANOVA, Independent Samples T-test, and Tukey HSD tests with the significance level set at 5%.

RESULTS

OMN exhibited a significantly superior BE compared to CTO and CDO, both before and after aging (p < 0.001). Color matching was significantly better at 1.5 mm than at 3 mm, except for CTO and CDO on the A3 background (p = 0.193 and p = 0.550, respectively). BE was highest on the A1 background, intermediate on B1, and lowest on A3 (p < 0.001). Translucency was significantly higher at 1.5 mm than at 3 mm (p < 0.001), except for CTO on A3 after aging (p = 0.198), while background shade did not affect translucency (p > 0.05).

CONCLUSIONS

The BE of single-shade resin composite is material and thickness-dependent. Overall, OMN demonstrated superior shade matching across different backgrounds compared to CDO and CTO, at both thicknesses, before and after aging.

CLINICAL SIGNIFICANCE

Understanding the influence of composite material, thickness, and underlying shade can optimize color matching in dental restorations, improving clinical outcomes and esthetics.

Evaluation of color stability in single-shade composite resins using spectrophotometer and cross-polarized mobile photography

BACKGROUND

This study aimed to evaluate the long-term color stability of single-shade composite resins when exposed to simulated intraoral conditions, including staining, brushing, and thermal cycling. Additionally, the study compared the performance of spectrophotometry and cross-polarized (CP) photography in detecting color changes, focusing on their applicability for both clinical and research purposes.

MATERIALS AND METHODS

The study employed five single-shade composite resins (Omnichroma; OMN, Zenchroma; ZNC, Vittra APS Unique; VTR, Charisma One; CHR, and Essentia Universal; ESU) and one multi-shade composite resin (Filtek Z550: FLT) for testing. The specimens were subjected to thermal cycling, staining, and brushing to simulate intraoral conditions. Color measurements were conducted using a spectrophotometer and CP photography at the initial baseline (t0) and following each subsequent procedure 10-day (t1) and 1-year simulated staining, brushing and thermal cycling (t2). Color differences (ΔE1, ΔE2) were calculated using the CIEDE2000 formula. Statistical analyses included Shapiro-Wilk for normality, ANOVA and paired t-tests for parametric data, and Kruskal-Wallis and Wilcoxon tests for non-parametric data. Method consistency was evaluated with the Intra-Class Correlation Coefficient (ICC) (p < 0.05).

RESULTS

All composite groups demonstrated statistically significant color changes following the simulated conditions (p < 0.001). The CHR group exhibited the highest values for both ΔE1 and ΔE2, indicating the greatest degree of discoloration. The FLT and ZNC groups exhibited the lowest ΔE values across methods at various time points. A positive correlation was identified between spectrophotometer and CP photography measurements for all parameters (p < 0.001), although the correlation for ΔE1 and ΔE2 was less robust.

CONCLUSIONS

Single-shade composites display a high susceptibility to significant discoloration when subjected to simulated intraoral conditions, with CHR exhibiting the most pronounced alterations. Both spectrophotometry and CP photography were effective in assessing color stability, with CP photography offering a practical alternative for clinical settings. These findings offer insight into the aesthetic durability of single-shade composites and underscore the importance of long-term evaluations.

Assessing color mismatch in single-shade composite resins for enamel replacement

STATEMENT OF PROBLEM

Shade selection is a challenge in restorative dentistry. While single-shade composite resins may simplify this process, whether the color mismatch between this composite resin and the substrate is within acceptable levels to ensure successful outcomes is unclear.

PURPOSE

The purpose of this in vitro study was to assess the influence of background and surrounding shade, thickness, and proximity to the surrounding on color mismatch when shaded and single-shade composite resins are used in the center of an enamel layer.

MATERIAL AND METHODS

Two-layer specimens mimicking dentin (the background) and enamel (the surrounding and center) were prepared. Two shades were used for the background and the surrounding layer (OA1/A1 and OA3/A3). At the Ø3-mm center, 2 single-shade composite resins were placed, Omnichroma (OM) and Admira Fusion x-tra (FU), and also shaded composite resins A1, WE, A3, and C2. For the OA1/A1 background and surrounding, shades A1 and WE served as positive controls, while the A3 and C2 were negative controls. For OA3/A3, these controls were reversed. Two enamel layer thicknesses were evaluated (0.5- and 1.0-mm). Reflectance measurements were made at 0.0, 1.0, 2.0, and 2.5 mm from the center. Color differences were calculated between those at 2.5 mm and at other distances (ΔE0, ΔE1, and ΔE2). Data analysis employed a 4-way repeated measure ANOVA with Bonferroni corrections for the pair-wise comparisons (α=.05).

RESULTS

Background and surrounding shade, central shade, distance, and thickness affected color mismatch (P<.05). For the OA1/A1 specimens, single-shade color mismatch values were found between both the positive and negative controls (P<.05). For the OA3/A3 specimens, the color mismatch did not differ significantly from that of negative controls (P>.05). No difference was found between ΔE0 and ΔE1, but each was distinct from ΔE2. Thickness did not affect the color mismatch of the single-shade composite resins (P<.05).

CONCLUSIONS

Single-shade composite resins for enamel replacement showed higher color mismatches compared with positive controls.

Effect of surface sealant on the color stability and whiteness index of single-shade resin composites after staining and bleaching

Objectives

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.

Materials and Methods

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).

Results

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).

Conclusions

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.

Surrounding and background shades effect on color adjustment of single-shade composites

This study evaluated the effects of surrounding and background shades on the color adjustment potential (CAP) and visual color match of two single-shade composites, Vittra APS Unique and Charisma Diamond One. Cylinder-shaped specimens were constructed, consisting of either single-shade composites alone (simple) or composites surrounded by the Forma material at shades A1 or A3 (dual). Simple specimens using only the Forma at the specified shades were also prepared. Color measurements of simple specimens were taken against a gray background using a spectrophotometer. For dual specimens, the color of the inner composite was measured against a gray or chromatic (the same shade as the outer composite) background. Color differences (ΔE00) between the single-shade composites and the A1/A3 composite were calculated. CAP was determined by comparing data from simple and dual specimens. Four experienced dentists scored the color match (perfect to unacceptable) for each specimen using a viewing booth illuminated by an illuminant D65. Data were analyzed with repeated-measures ANOVA and the Kruskal-Wallis test. The results showed that both single-shade composites showed the lowest color discrepancies when they were compared to A1 and A3. Using a chromatic background only significantly affected the CAP when the outer composite was A3. The visual analysis showed poor color matches between the single-shade and control chromatic composites, except for Charisma Diamond One surrounded by A1. In conclusion, the CAP values of the evaluated single-shade composites were impacted by both surrounding shade and background color, and the color match of these materials tended to be poor.

Color discrepancy of single-shade composites at different distances from the interface measured using cell phone images

Objectives

This study aimed to evaluate the impact of substrate color and interface distance on the color adjustment of 2 single-shade composites, Vittra APS Unique and Charisma Diamond One.

Materials and Methods

Dual disc-shaped specimens were created using Vittra APS Unique or Charisma Diamond One as the center composite, surrounded by shaded composites (A1 or A3). Color measurements were taken with a spectrophotometer against a gray background, recording the color coordinates in the CIELAB color space. Illumination with a light-correcting device and image acquisition using a polarizing filter-equipped cell phone were performed on specimens over the same background. Image processing software was used to measure the color coordinates in the center and periphery of the inner composite and in the outer composite. The color data were then converted to CIELAB coordinates and adjusted using data from the spectrophotometer. Color differences (ΔE00) between the center/periphery of single-shade and outer composites were calculated, along with color changes in single-shade composites caused by different outer composites. Color differences for the inner composites surrounded by A1 and A3 were also calculated. Data were analyzed using repeated-measures analysis of variance (α = 0.05).

Results

The results showed that color discrepancies were lowest near the interface and when the outer composite was whiter (A1). Additionally, Charisma Diamond One exhibited better color adjustment ability than Vittra APS Unique.

Conclusions

Color discrepancies between the investigated single-shade composites diminished towards the interface with the surrounding composite, particularly when the latter exhibited a lighter shade.