Evaluating visual thresholds and color metrics in dental research: An exploratory study

Area of Science:

• Dental materials science
• Colorimetry
• Visual perception

Background:

• Accurate dental color measurement is crucial for esthetic restorations.
• Existing color difference equations and measurement devices have varying performance.
• Understanding perceptibility (PT) and acceptability thresholds (AT) is key for clinical application.

Purpose of the Study:

• To evaluate perceptibility (PT) and acceptability thresholds (AT) for multiple color measurement devices.
• To assess the performance of three color difference equations (∆E*_ab, ∆E₀₀, and ∆E₉₄) using expert visual data.
• To compare the effectiveness of different color difference metrics in dental colorimetry.

Main Methods:

• Extended a published visual dataset with the x-rite MetaVue spectrophotometer and ∆E₉₄ analysis.
• Used magnitude estimation for visual scaling on 26 tooth sample pairs.
• Determined PT and AT using a model-free method and analyzed device performance with STRESS and VIAS metrics.

Main Results:

• Perceptibility and acceptability thresholds varied significantly across devices and color difference equations.
• ∆E*_ab showed excellent visual-instrumental agreement (STRESS 18-36, VIAS 64-82%) outperforming ∆E₀₀ (STRESS 23-32, VIAS 68-77%) and ∆E₉₄ (STRESS 24-42, VIAS 58-76%).
• The x-rite MetaVue performed well under controlled conditions but is unsuitable for clinical research.

Conclusions:

• Device-specific thresholds for PT and AT are necessary due to observed variability.
• ∆E*_ab is a more effective and simpler metric for dental colorimetry compared to ∆E₀₀ and ∆E₉₄.
• This research provides valuable insights for selecting appropriate color measurement devices and metrics in dentistry.