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

Abstract

Objectives

This study assessed the reliability of digital color measurements using images of resin composite specimens captured with a cellphone.

Materials and Methods

The reference color of cylindrical specimens built-up with the use of resin composite (shades A1, A2, A3, and A4) was measured with a portable spectrophotometer (CIELab). Images of the specimens were obtained individually or pairwise (compared shades in the same photograph) under standardized parameters. The color of the specimens was measured in the images using RGB system and converted to CIELab system using image processing software. Whiteness index (WI _D) and color differences (ΔE ₀₀) were calculated for each color measurement method. For the cellphone, the ΔE ₀₀ was calculated between the pairs of shades in separate images and in the same image. Data were analyzed using 2-way repeated-measures analysis of variance (α = 0.05). Linear regression models were used to predict the reference ΔE ₀₀ values of those calculated using color measured in the images.

Results

Images captured with the cellphone resulted in different WI _D values from the spectrophotometer only for shades A3 and A4. No difference to the reference ΔE ₀₀ was observed when individual images were used. In general, a similar ranking of ΔE ₀₀ among resin composite shades was observed for all methods. Stronger correlation coefficients with the reference ΔE ₀₀ were observed using individual than pairwise images.

Conclusions

This study showed that the use of cellphone images to measure the color difference seems to be a feasible alternative providing outcomes similar to those obtained with the spectrophotometer.