Gingival bleeding and calculus among 12-year-old Chinese adolescents: a multilevel analysis

BMC Oral Health

Table 5 Selected variables using training data shown to be associated with dental calculus, evaluated by multi-level logistic regression analyses (n = 3394)

Variables	Categories	Null model	Model with individual and contextual variables
Variables	Categories		OR (95% CI)	p
Fixed effect
Individual level
Gender	Female		1
Gender	Male		1.32 (1.13, 1.54)	< 0.01
*hukou*	Rural		1
*hukou*	Urban		0.69 (0.59 0.82)	< 0.01
Family size	One child		1
Family size	More than one child		1.34 (1.12, 1.59)	< 0.01
Father’s educational level	Middle school or lower ^a		1
Father’s educational level	More than middle school^b		0.46 (0.39 0.54)	< 0.01
Mother’s educational level	Middle school or lower ^a		1
Mother’s educational level	More than middle school^b		0.65 (0.59 0.82)	< 0.01
Brushing frequency (times/day)	Never		1
	Sometimes		1.76 (1.21, 2.54)	< 0.01
	One		1.04 (0.771.42)	0.79
	≥Twice		0.57 (0.42 0.78)	< 0.01
Dental floss use	Never		1
Dental floss use	Yes		0.66 (0.48 0.90)	0.01
Sugar-containing soft drink/Pop/ milk/yogurt/tea/coffee/water	≤1/week		1
	> 1/week		1.30 (1.11 1.53)	< 0.01
Dental visit (last year)	No		1
Dental visit (last year)	Yes		1.15 (0.96 1.39)	0.14
Frequency of dental curricula (last semester)	0		1
Frequency of dental curricula (last semester)	≥1		0.85 (0.67, 1.07)	0.16
Random effect
Contextual level variance (SE^c)		0.065 (0.42)	0.12 (0.07)	0.11
AIC^d		4277.8	3985.3
Average intercept		0.715	1.06365
VPC^e		0.01438	0.022693

Abbreviations: ^aMiddle school or lower: ≤9 years; ^bMore than middle school: >9 years; ^cSE standard error, ^dAIC Akaike Information Criteria, ^eVPC variance partitioning coefficient

ISSN: 1472-6831