Reliability of Three Image-Based Instrumental Color-Measurement Methods

Area of Science:

• Dental Materials Science
• Colorimetry
• Digital Imaging

Background:

• Accurate color assessment of dental composites is crucial for aesthetic restorations.
• Existing clinical methods for color measurement vary in precision.
• Image-based color assessment tools are increasingly accessible but require validation.

Purpose of the Study:

• To compare the precision of smartphone imaging, Optishade, and Borea Cobra against a spectrophotometer for measuring composite resin shades.
• To evaluate CIELAB coordinates and CIEDE2000 (ΔE₀₀) color differences.

Main Methods:

• Three specimens from eight composite shades were measured using a benchtop spectrophotometer (reference) and three test devices.
• Agreement for L*, a*, and b* was assessed using linear regression and Bland-Altman analyses.
• ΔE₀₀ values were analyzed using two-way ANOVA and regression.

Main Results:

• Optishade demonstrated the closest agreement with the reference, showing minimal bias and narrow limits of agreement.
• Borea Cobra performed well, with strong agreement for a* and b*, but exhibited greater data dispersion.
• Smartphone measurements showed systematic bias, reduced precision, and compression of color differences.

Conclusions:

• Optishade is the most reliable device for quantitative color measurements of composite resins.
• Borea Cobra offers acceptable performance with certain limitations.
• Smartphone imaging preserves shade order but is not precise enough for quantitative color analysis.