Background/purpose: Color-changeable chewing gum is used for the evaluation of masticatory performance. However, it is currently unclear whether colorimetric and visual assessment methods yield consistent results. This study aimed to clarify the consistency between colorimetric and visual methods used for the evaluation of color changes in color-changeable chewing gum. Materials and methods: The sample comprised 644 older persons (mean age, 75.4 ± 6.4 years). The chewing gum was masticated 60 times at the participant's own chewing rate and then expectorated. The color of the chewing gum was evaluated with the ΔE values and a∗ values, measured using a colorimeter, and the 10 Color Shades (10CSh) and 5 Color Scales (5CSc), using visual evaluation. Spearman's correlation analysis was performed to examine the correlation between the results obtained by the four methods. The significance level was set at α = 0.05. Results: The ΔE values, a∗ values, 10CSh scores, and 5CSc scores were all significantly correlated. The highest correlation coefficient (0.979) was between the ΔE values and a∗ values. The lowest correlation coefficient (0.847) was between the a∗ values and 5CSc scores. Decreased masticatory performance was observed with increased age. Conclusion: Significant correlations were found for all four methods used in the assessment of masticatory performance with color-changeable chewing gum. While visually based assessments are valid, colorimetric methods are more sensitive to smaller changes in masticatory performance.
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