A new masticatory performance scale to integrate food biting, comminution and mixing ability in removable partial denture wearers.

BACKGROUND The existing masticatory performance (MP) tests cannot comprehensively evaluate objective masticatory function. OBJECTIVES We aimed to examine the construct validity and responsiveness and determine the clinically minimum important difference (MID) and related factors of a newly developed MP scale to integrate food biting, comminution and mixing ability in patients with removable partial dentures (RPDs). METHODS Masticatory performance tests using gummy jelly, peanuts and colour-changeable gum were performed before and 3 months after RPD treatment in 248 partially dentate patients. A 10-point ordinal subscale was created for each MP test based on the distributions of MP values, and the three subscales were integrated into a single scale (iMP scale). We analysed the correlations between MP values and iMP scores and determined the effect size for RPD treatments and the MID on the basis of patient perception of chewing ability. RESULTS iMP scores exhibited moderate correlations with the three MP values (|ρ| = 0.73-0.79, p < .001) and with the change scores (|ρ| =0.61-0.64, p < .001). The mean iMP score significantly increased after RPD treatment (p < .001), and the effect size was 0.35. Of the 248 patients, 55 (22%) reported a slight improvement in chewing ability with a mean iMP score change of 2.1 points. Sex and the number of missing teeth were significantly associated with iMP scores (p < .05). CONCLUSIONS The iMP scale comprehensively evaluated objective masticatory function, including food biting, comminution and mixing ability in RPD wearers, and an increase of two points on the iMP scale was considered to be the MID in RPD treatments.