Which Norm of Mixing Ability Index to Evaluate Deficiency in Masticatory Performance in Young Adults?

Background The two-coloured chewing gum test is widely used to quantify oral mixing ability. Lack of consensual normative reference values limits its interpretation and comparability across studies.Objective To present the methodology establishing normative reference cut-offs for masticatory mixing ability in healthy young adults using two-coloured chewing gums.Methods Data from 61 healthy individuals (22.08 ± 2.22 years) who fulfilled anatomical (≥ 7 posterior functional units), psychosocial (GOHAI ≥ 52) and physiological (carrot D50 < 4 mm) criteria for good oral health were considered. Mixing ability was measured after 5 cycles, 20 cycles and 1 min with two different gum types (Hue-Check Gum and Hollywood gum). Outcomes were SD-Hue and Mix%.Results Mix% increased significantly from 5 to 20 cycles for both gums and approached maximal values after 1 min (p < 0.001). At 20 cycles, mean Mix% was 81.06% (95% CI: 78.46-83.66) for Hollywood and 88.31% (95% CI: 85.44-91.17) for Hue-Check Gum. Corresponding mean SD-Hue values were 0.076 (95% CI: 0.068-0.084) and 0.108 (95% CI: 0.085-0.131), respectively. Normative reference cut-offs at 20 cycles were defined using the lower bound of the 95% CI for Mix% (78.46% for Hollywood and 85.44% for Hue-Check Gum) and the upper bound of the 95% CI for SD-Hue (0.084 for Hollywood and 0.131 for Hue-Check Gum).Conclusion Normative reference cut-offs for the two-coloured chewing gum test are provided for healthy young adults, enabling standardized interpretation of mixing outcomes. However, their applicability across other age groups is needed.