Color assessment of resin composite by using cellphone images compared with a spectrophotometer

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.

Comparison of instrumental methods for color change assessment of Giomer resins

Objectives

The aim of this study was to compare the color change of the Giomer resin composite (Beautifil-Bulk) by using photographs obtained with a smartphone (iPhone 6S) associated with Adobe Photoshop software (digital method), with the spectrophotometric method (Vita Easyshade) after immersion in different pigment solutions.

Materials and Methods

Twenty resin composite samples with a diameter of 15.0 mm and thickness of 1.0 mm were confectioned in A2 color (n = 5). Photographs and initial color readings were performed with a smartphone and spectrophotometer, respectively. Then, samples were randomly divided and subjected to cycles of immersion in distilled water (control), açai, Coke, and tomato sauce, 3 times a day, 20 minutes for 7 days. Later, new photographs and color readings were taken.

Results

The analysis (2-way analysis of variance, Holm-Sidak, p < 0.05) demonstrated no statistical difference (p < 0.005) between the methods in all groups. Similar color changes were observed for all pigment solutions when using the spectrophotometric method. For the digital method, all color changes were clinically unacceptable, with distilled water and tomato sauce similar to each other and with statistical differences (p < 0.005) for Coke and açai.

Conclusions

Only the tomato sauce produced a color change above the acceptability threshold using both methods of color assessment. The spectrophotometric and digital methods produce different patterns of color change. According to our results, the spectrophotometric method is more recommended in color change assessment.