[A study on the differences in function of free-sided and unilateral chewing].
OBJECTIVE
Unilateral chewing requires a greater number of chewing strokes up to the point of the first swallowing. The rate of storage of ground food particles in the oral vestibule is said to be high during unilateral chewing. However, influence of the masticatory method, that is free-sided or unilateral chewing, involved in masticatory efficiency has not been elucidated. On that point, in order to clearly represent the effects that free-sided (bilateral) chewing and unilateral chewing have on the chewing efficiency, our purpose was to examine the difference of the functions of both free-sided chewing and unilateral chewing.


METHODS
We used 116 dentate subjects with normal occlusal relations, and compared the number of chewing strokes for peanuts up to the point of the first swallowing (abbreviated as "chewing strokes") for both free-sided chewing and unilateral chewing. Following this, we made calculations regarding the amount of saliva secretion, occlusal force, and contact points of posterior teeth. Based on the averages of three parameters (saliva secretion, occlusal force and contact points of posterior teeth), all the subjects were classified into two groups (high score group and low score group). In the two groups, we counted the difference in the number of free-sided chewing and unilateral chewing. And also in two groups, the amount of remaining coarse particles immediately prior to the first swallowing was investigated between free-sided chewing and unilateral chewing.


RESULTS
The number of chewing strokes by free-sided chewing for all subjects was 10% less than that of unilateral chewing. Furthermore, the numbers of chewing strokes by free-sided chewing were all less than those of unilateral chewing in both groups on three parameters. The amount of remaining coarse particles by free-sided chewing was significantly smaller than that of unilateral chewing in the low score group of saliva secretion and occlusal force.


CONCLUSIONS
The number of chewing strokes by free-sided chewing was less than that of unilateral chewing in both of the high score group and low score group on the amount of saliva secretion, occlusal force, and contact points of posterior teeth.
Honma
Kazuyo
K
Division of Removable Prosthodontics, Niigata University Graduate School of Medical and Dental Sciences. honma@meirin-c.ac.jp
Kohno
Shoji
S
Honma
Wataru
W
Sakurai
Naoki
N
D000328:Adult; D001732:Bite Force; D005260:Female; D006801:Humans; D008409:Mastication / Q000502:physiology*; D012472:Salivation / Q000502:physiology