Table 5.

Changes of standard deviation of masticatory efficiency in the two groups before and after treatment (x̅ ± sd)

Group	Number of cases	In pre-treatment	In post-treatment	t	P
The observation group	49	0.86±0.35	0.53±0.15	6.066	0.000
The control group	49	0.88±0.29	0.64±0.13	5.286	0.000
t	-	0.308	3.879	-	-
P	-	0.759	0.000	-	-