Table 3.

The prevalence of dental caries of first permanent molars of the surveyed children according to different variables studied (N = 2,849)

Variable		N	Prevalence of dental caries of FPMs	P-value*
sibling	no	1,734	4.8%	0.080
	yes	1,115	6.4%
Father’s educational background	High (college or above)	1,926	4.4%	< 0.001
	Low (senior school or below)	923	7.7%
Mother’s educational background	High (college or above)	1,940	4.7%	0.016
	Low (senior high school or below)	909	6.9%
Frequency of toothbrushing	≥ 2/d	2,001	4.9%	0.075
	< 2/d	848	6.6%
Sweets intake	Everyday	234	6.4%	0.495
	Not everyday	2,615	5.4%
The use of dental floss	Everyday	109	1.8%	0.003
	Not everyday	2,740	5.6%

*Chi-square test