Table 2

Characteristics of participants, by presence of malocclusion

 Malocclusion (−)Malocclusion (+)
All (n=557, 100%)(n=361, 65%)(n=196, 35%)
N or meanPer cent or SDN or meanPer cent or SDN or meanPer cent or SDp for χ2 test
Age of father†40.35.840.65.839.75.60.13
Age of mother†38.65.538.85.738.35.10.31
Education level of father
 High13925862453270.69
 Intermediate25446163459146
 Low1132077213618
Education level of mother
 High209381223487440.037*
 Intermediate24344164457940
 Low1051975213015
Family income level
 High9717611736180.86
 Intermediate289521895210051
 Low16029105295528
Number of children in the family†2.61.12.61.02.61.10.62
Dwelling
 Traditional ‘ger’13324922641210.56
 Detached house21939139398041
 Apartment complex20437129367538
School location
 Outside of the centre of the city263471774986440.25
 At the centre of the city294531845111056
Drinking habit of mother during pregnancy
 (+)183123630.99
 (−)496893218917589
Smoking habit of mother
 (+)16393740.30
 (−)540973529818896
X-ray exposure during pregnancy
 (+)10218701932160.23
 (−)366662406712664
Age of participant†12.81.312.81.312.91.30.20
Birth weight
 <2500 g193164320.15
 ≥2500 g473853068516785
Gestational age at birth
 <37 weeks of pregnancy285216740.18
 ≥37 weeks of pregnancy507913299117891
Type of feeding in early childhood
 Breast feeding only3856925370132670.018*
 Mixed feeding1332488244523
 Bottle feeding only316195126
Use of a pacifier during childhood
 (+)9918601739200.11
 (−)442792948114876
Finger-sucking habit during childhood
 (+)3672161580.43
 (−)506913329217489
Frequency of tooth brushing
 More than once a day233421594474380.35
 Once a day25746160449750
 Not every day621140112211
Regular breakfast
 (+)3336021760116590.83
 (−)22440144408041
  • *p<0.05.

  • †Continuous variables were analysed using Student's t-test.