Table 3

Distribution of occlusal traits and malocclusion requiring treatment by education level of mother

	All (n=557, 100%)		Education level of mother
			Low		Intermediate		High
			(n=105, 19%)		(n=243, 44%)		(n=209, 38%)
	N or mean	Per cent or SD	N or mean	Per cent or SD	N or mean	Per cent or SD	N or mean	Per cent or SD	p for χ² test
Occlusal traits not used for diagnosis
Dental age
III B	99	18	16	15	42	17	41	20	0.15
III C	290	52	66	63	122	50	102	49
IV A	168	30	23	22	79	33	66	32
Midline discrepancy (mm)†	0.8	1.0	0.8	1.0	0.8	0.8	0.9	1.1	0.17
Tooth size of upper left incisor (mm)†	8.7	0.7	8.7	0.5	8.6	0.9	8.8	0.5	0.07
Level of dental caries (sum of decayed, filled teeth for mixed and permanent dentition)†	5.6	3.5	5.5	3.3	5.9	3.6	5.4	3.3	0.29
Occlusal traits used for diagnosis
Increased overjet which needs treatment
>6 mm	20	4	4	4	9	4	7	3	0.97
≤6 mm	537	96	101	96	234	96	202	97	0.97
Reverse overjet which needs treatment
>1 mm	12	2	1	1	5	2	6	3	0.54
≤1 mm	545	98	104	99	238	98	203	97	0.54
Deep bite
Deep bite causing notable indentations of the palatal gingivae	5	1	1	1	0	0	4	2	0.10
Deep bite or normal overbite without indentations or signs of trauma	552	99	104	99	243	100	205	98	0.10
Open bite which needs treatment
>4 mm	1	0	0	0	0	0	1	1	0.43
≤4 mm	556	100	105	100	243	100	208	100	0.43
Anterior crossbite
(+)	60	11	9	9	24	10	27	13	0.42
(−)	497	89	96	91	219	90	182	87	0.42
Posterior crossbite
(+)	48	9	8	8	21	9	19	9	0.91
(−)	509	91	97	92	222	91	190	91	0.91
Scissor bite
(+)	30	5	5	5	15	6	10	5	0.77
(−)	527	95	100	95	228	94	199	98	0.77
Displacement of teeth in the maxillary arch which needs treatment
>4 mm	70	13	13	12	28	12	29	14	0.75
≤4 mm	487	87	92	88	215	89	180	86	0.75
Displacement of teeth in the mandibular arch which needs treatment
>4 mm	20	4	5	5	11	5	4	2	0.26
≤4 mm	537	96	100	95	232	96	205	98	0.26
Cleft lip and/or palate
(+)	1	0	0	0	0	0	1	1	0.43
(−)	556	100	105	100	243	100	208	100	0.43
Hypodontia which needs treatment
(+)	26	5	2	2	8	3	16	8	0.030*
(−)	531	95	103	98	235	97	193	92	0.030*
Impeded eruption
(+)	11	2	3	3	1	0	7	3	0.06
(−)	546	98	102	97	242	100	202	97	0.06
Partially erupted teeth, tipped and impacted against adjacent teeth
(+)	10	2	2	2	4	2	4	2	0.97
(−)	547	98	103	98	239	98	205	98	0.97
Presence of supernumerary teeth
(+)	2	0	0	0	2	1	0	0	0.27
(−)	555	100	105	100	241	99	209	100	0.27
Molar relationship by Angle Classification
Class I	349	63	57	54	150	62	142	68	0.006*
Class II	113	20	27	26	46	19	40	19
Class III	37	7	6	6	13	5	18	9
Not applicable	58	10	15	14	34	14	9	4
Diagnosed malocclusion
Grade 1	39	7	7	7	20	8	12	6	0.13
Grade 2	110	20	24	23	50	21	36	17
Grade 3	212	38	44	42	94	39	74	35
Grade 4	181	33	27	26	77	32	77	37
Grade 5	15	3	3	3	2	1	10	5
Malocclusion requiring treatment
(+)	196	35	30	29	79	33	87	42	0.037*
(−)	361	65	75	71	164	68	122	58	0.037*

*p<0.05.
†Continuous variables were analysed with analysis of variance (ANOVA).