Table 3.

Mean ± SD plaque, gingival, and calculus indices for the 12-year-old age group by gender, area of residence, and governorate.

	Plaque index	Calculus index	Gingival index
Gender
Male (n = 2052)	1.17 ± 0.60	0.09 ± 0.18	1.03 ± 0.64
Female (n = 2052)	1.06 ± 0.49	0.04 ± 0.13	0.91 ± 0.62
Total (n = 4104)	1.12 ± 0.55	0.07 ± 0.16	0.97 ± 0.64
t -test	<0.001	<0.001	<0.001
Area of residence (for 12 years)
Urban (n = 1520)	1.12 ± 0.53	0.07 ± 0.19	1.01 ± 0.56
Rural (n = 1292)	1.19 ± 0.54	0.07 ± 0.15	1.02 ± 0.69
Periurban (n = 1292)	1.04 ± 0.57	0.05 ± 0.14	0.88 ± 0.65
Total (n = 4104)	1.12 ± 0.55	0.07 ± 0.16	0.97 ± 0.64
ANOVA	<0.001	0.005	<0.001
Governorate
Sana'a (n = 1216)	1.26 ± 0.49	0.03 ± 0.12	1.38 ± 0.31
Taiz (n = 836)	0.71 ± 0.56	0.02 ± 0.08	0.54 ± 0.59
Hodeida (n = 684)	1.01 ± 0.67	0.10 ± 0.20	0.61 ± 0.63
Hajjah (n = 684)	1.33 ± 0.34	0.04 ± 0.11	1.43 ± 0.31
Hadramaut (n = 684)	1.25 ± 0.69	0.16 ± 0.25	0.69 ± 0.63
Total (n = 4104)	1.12 ± 0.55	0.049 ± 0.14	0.97 ± 0.64
ANOVA	<0.001	<0.001	<0.001