Related factors of periodontal health among Chinese middle school students, findings from a national cross-sectional survey

Table 4 The generalized linear mixed model of calculus

	Coefficient	Sig.	Exp (coefficient)	95% CI for exp (coefficient)
	Coefficient	Sig.	Exp (coefficient)	Lower	Upper
Intercept	1.17		3.23	2.34	4.47
Gender
Male	0.28	< 0.001	1.32	1.28	1.36
Female^a
Age
12	− 0.67	< 0.001	0.51	0.49	0.53
13	− 0.48	< 0.001	0.62	0.59	0.64
14	− 0.25	< 0.001	0.78	0.75	0.82
15^a
Ethnic group
Han	− 0.10	.003	0.91	0.86	0.96
Minority^a
Family structure
One-child family	− 0.13	< 0.001	0.88	0.85	0.91
With siblings^a
Father education
Middle school	0.23	< 0.001	1.26	1.20	1.33
High school	0.11	< 0.001	1.12	1.08	1.17
University^a
Brush teeth
Yes	− 0.11	< 0.001	0.90	0.85	0.95
No^a
Dental floss
Yes	− 0.18	< 0.001	0.83	0.79	0.87
No^a
Oral health knowledge
0–3	0.06	.002	1.06	1.02	1.11
4–5	0.06	.001	1.06	1.03	1.09
6–8^a

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