THE EFFECT OF THE CHANGING DENTITION ON MASTICATORY FUNCTION

¹ Oral Pediatrics Department and the Laboratory for Oral Physiology, Tufts College Dental School, Boston, Mass.

An investigation has been made of 400 children from 6 to 15 years of age in order to determine the effect of the changing dentition on masticatory function. Masticatory performance, swallowing threshold, food platform area and the maximum biting force were determined on both sides of the dentitions. It was possible to predict masticatory efficiency from masticatory performance with considerable accuracy. The masticatory performances with peanuts, P_p, were well correlated with the performances with carrots, P_c, with efficiency, E_p, and with the swallowing threshold, U_p.

The masticatory efficiencies of the children extended over a wide range and averaged about half that of adults who had all teeth except the third molar present. The first and second permanent molars did not improve masticatory function immediately after eruption, but efficiency gradually increased over a period of three to four years. Efficiency declined after age 10 and rose again by age 14, probably because of the time required for the recently erupted teeth to become functional.

Forty-seven per cent of 400 cases investigated were classed as malocclusions by orthodontic criteria. Only the Class III cases showed a low area and a corresponding low performance. Other malocclusions were similar to normal cases in their average masticatory function. There was no significant difference in the efficiency of males and females with similar ages and a limited range in area. Food platform area was less well correlated with efficiency (.57) than was found previously among adults.

The maximum biting force had little relationship to masticatory efficiency or food platform area. The tendency to prefer the right side in mastication predominated over the tendency to prefer the more efficient side in mastication.