RESUMO
OBJECTIVES: The study objectives were: 1) to develop a masticatory index for evaluating masticatory ability in patients wearing a dental prosthesis, including complete dentures (CD), removable partial denture (RPD), and fixed partial denture (FPD), 2) to test the reliability and validity of the index, and 3) to determine whether the index better reflected patients' masticatory ability compared with conventional subjective and objective measures. METHODS: The present cross-sectional study consisted of 2 phases: 1) developing the Chulalongkorn University masticatory index (CUMI) consisting of 20 food items in 5 masticatory difficulty grades using a 3-point Likert scale, and 2) application of the CUMI in 110 patients wearing a dental prosthesis, including CD, RPD, and FPD (control group). The CUMI test-retest reliability was reevaluated 2 weeks later. The convergent validity was compared with objective masticatory performance evaluated with a standard peanut chewing test, and subjective eating impacts evaluated by the Oral Impacts on Daily Performances Index. Oral and denture status were determined clinically. The associations between CUMI score, peanut particle size, and eating impact score was identified using Spearman's correlation coefficient. To evaluate discriminant validity, the associations between masticatory ability measurements and oral and denture status were analyzed using regression analyses. RESULTS: The CUMI's Cronbach's alpha and intraclass correlation coefficient values were 0.89 and 0.95, respectively. The convergent validity was shown by significant associations between the increased CUMI score, smaller peanut particle size and decreased eating impact score. Multivariable analyses found that the CUMI score, peanut particle size, and percentage of having an eating impact were significantly associated with the number of remaining teeth and posterior occluding pairs, and type and quality of dental prosthesis. However, the CUMI demonstrated better discriminant validity because significant dose-response relationships were found only between the decreased CUMI score and increased tooth loss severity, and unacceptable denture quality. Adjusted R2 values of the CUMI models were the highest, followed by those of peanut particle size and eating impact. CONCLUSION: CUMI is a reliable and valid tool to evaluate masticatory ability of patients wearing a dental prosthesis, including CD, RPD, and FPD. Due to a better discriminant validity, the CUMI better reflects masticatory ability of patients compared with conventional subjective and objective masticatory ability measures.
