Table 2. Periodontal knowledge among orthodontic patients according to age, gender and duration of treatment (subjects with correct answers).

Questions	Age		Gender		Duration of treatment		Total n (%)
	Adolescents	Adults	Female	Male	<18 month	≥18 month
	(n= 119) n (%)	(n=178) n (%)	(n=207) n (%)	(n=90) n (%)	(n=231) n (%)	(n=66) n (%)
What is dental plaque?	29 (24%)	49 (27.5%)	48 (23%)	30 (33%)	60 (26 %)	18 (27%)	78 (26%)
	(X2= 0.655; P=0.884)		(X2= 3.346; P=0.341)		(X2=0.697; P=0.874)
What can dental plaque cause?	3 (2.5)	12 (7%)	12 ( 6%)	3 (3%)	13 ( 6%)	2 ( 3%)	15 (5 %)
	(X2= 3.335; P=0.343)		(X2=10.506; P=0.015*)		(X2=0.811; P=0.847)
What bleeding gum indicates?	79 (66%)	129 (72.5%)	152 (73%)	56 (62%)	161 (69 %)	47 (71%)	208 (70%)
	(X2=3.409; P=0.333		(X2= 4.334; P=0.228)		(X2=1.088; P=0.780)
How can you prevent gum disease?	66 (55.5%)	102 (57%)	110 (53%)	58 (64 %)	130 (56%)	38 (58%)	168 (57%)
	(X2=3.409; P=0.333)		(X2= 5.120; P=0.163)		(X2=1.394; P=0.707)