The effect of bolus size on masticatory parameters at swallowing threshold in children using a hard, solid, artificial test food

The effect of different bolus sizes on food breakdown has been studied in adults, but not in children. The objective of this study was to study median particle size (MPS) and other parameters of masticatory function at swallowing threshold (ST) in 8-10-year-old-children with two different bolus sizes. A randomized crossover trial was undertaken in 89 eight to ten-year-old children. The study was performed with informed consent and ethical approval. The artificial test food used was made of a condensation silicone (Optosil Comfort) following a standardized protocol. Two bolus sizes (three or four quarters of a 20-mm diameter, 5-mm thick tablet) were randomized to avoid an order effect and tested in different sessions. Variables were: MPS (X50 ) at ST, number of cycles until ST, sequence and cycle duration as well as cycles/g. Comparisons were performed with paired t and Wilcoxon tests, regressions and correlations were run. Cutoff for statistical significance was .05. Statistically significant differences were found for all variables; X50 (2.5 ± 0.8 vs. 2.8 ± 0.7 mm, p < .001), cycles until ST (38 vs. 40, p = .022), sequence (25 vs. 27 s, p = .003), and cycle duration (650 vs. 683 ms, p = .015) and cycles/g (27 vs. 21 cycles/g, p < .001), three or four quarters, respectively. In conclusion, in children, as in adults, chewing on a bigger bolus size leads to a larger MPS (X50 ) at ST. When chewing on a larger bolus the number of cycles increases, but not enough to swallow the same particle size since the number of cycles/g is less with a bigger bolus size.