Masticatory Performance: Particle-size Distributions Determined Using Optical Scanning Versus Sieving

OBJECTIVES: The standard procedure for the determination of masticatory performance is the fractionated sieving of comminuted test-food, which is time-consuming. Aim of this study was to introduce a comparable feasible and valid technique based on scanning. METHODS: Twenty-one chewing samples (Optosil) were comminuted by healthy dentate adults and analysed by a sieving and scanning method. The sieving procedure was carried out using ten sieves (5.6-4.0-2.8-2.0-1.4-1.0-0.71-0.5-0.355-0.25 mm), the retained particles per sieve were weighed. Scanning was performed with a conventional flatbed scanner (Epson Expression1600Pro, Seiko-Epson-Corporation, Japan, 1200dpi). All scanned images underwent image analysis (ImageJ1.42q, NIH, USA ), which yielded descriptive parameters such as area, best-fitting ellipse etc. for each particle. Out of the 2D-image, a volume was estimated for each particle, which was converted into a weight. In order to receive a discrete distribution of particle sizes comparable to sieving, five chewing samples were used to calculate a size-dependent area-volume-conversion factor. The cumulated weights yielded by either method were curve-fitted with the Rosin-Rammler-distribution using a least-square-method (Matlab, The-Mathworks-Inc., Natick, USA) to determine the median particle size x50. RESULTS: The Rosin-Rammler distributions for sieving and scanning resemble each other. The distributions show a high correlation (0.919-1.0, N = 21, P < 0.01, Pearson's Correlation Coefficient). The median particle sizes were vary between 3.83 and 4.77mm (mean: 4.31) for scanning and 3.53 and 4.55mm (mean: 4.21) for sieving. On average, scanning overestimates the x50 values by 2.4%. A modified Bland-Altman-Plot reveals that 95% of the x50 values fall within 10% of the average x50. The scanning method took 10 min per sample as opposed to 50 min for the sieving method. CONCLUSION: The scanning method is a valid, simple and feasible method to determine masticatory performance.