Comparison of chewing cycles in 2-, 3-, 4-, and 5-year-old normal children.

Chewing movements of normal 2-, 3-, and 4-year-old children were measured. Chewing movements of 2- and 3-year-olds were compared with those of 4- and 5-year-olds. Measures were taken on 56 children: 17 were 2 years old (8 female, 9 male); 19 were 3 years old (10 female, 9 male); and 20 were 4 years old (10 female and 10 male). Data of twenty 5-year-olds (10 males, 10 females) were taken from a previous study (9). Chewing movements were measured by time (seconds), number of cycles, and a time/cycle ratio. A chewing cycle was defined as an upward and downward movement of the chin. Total time from the moment food was placed in the mouth until the final swallow occurred was divided by the number of cycles counted for the same period. The type of food eaten affected time, cycles, and the time/cycle ratio, but age and sex did not. A comparison of younger (2- and 3-year-olds) and older children (4- and 5-year-olds) showed significant time differences. During maturation, time was shortened. It was shown earlier that under pathologic conditions (Down's syndrome) time was prolonged. Thus, the time/cycle ratio is an excellent indicator of the developmental status of a child.