Lack of agreement between objective and subjective measures in the evaluation of masticatory function: A preliminary study.

The evaluation of mastication is important to understand the masticatory behavior and diagnose feeding difficulties. The objective of this preliminary study was to verify if there is agreement between objective and subjective validated methods of chewing evaluation in a convenience sample which consisted of 32 adolescents (mean 15.5years), complete permanent dentition and free of tooth decay. The Quality of Masticatory Function Questionnaire with the Food-Mastication, Habits, Meat, Fruit and Vegetables domains was used in the subjective evaluation. The objective aspects consisted of maximum bite force (BF) and masticatory performance (MP) by mastication of cubes of test-material and sieving to determine the median particle size (X) and distribution in the sieves ("b"), and by the colorimetric method using colorchangeable chewing gum. Data were submitted to exploratory analysis, normality test and correlation tests (Pearson/Spearman). The correlation between BF and X (r=-0.43; p=0.02) and between BF and MP chewing gum (r=0.53; p=0.002) was significant with large effect size. The MP evaluated by chewing gum correlated with X (r=-0.34; p=0.055), but not with "b" (r=-0.06; p=0.73), while "b" correlated only with X (r=0.52, p=0.002). No significant correlation was observed between the objective measures and the total score of the subjective evaluation; only a negative correlation was observed between "b" and Meat domain (r=-0.40; p=0.023). The objective methods showed moderate correlation with each other and no agreement between the objective and subjective methods was observed in this sample of healthy adolescents, emphasizing the importance of both aspects in the evaluation of masticatory function.