title: Effects of breast-feeding duration, bottle-feeding duration and non-nutritive sucking habits on the occlusal characteristics of primary dentition.
abstract: BACKGROUND
  Early transition from breastfeeding and non-nutritive sucking habits may be related to occlusofacial abnormalities as environmental factors. Previous studies have not taken into account the potential for interactions between feeding practice, non-nutritive sucking habits and occlusal traits. This study assessed the effects of breast-feeding duration, bottle-feeding duration and non-nutritive sucking habits on the occlusal characteristics of primary dentition in 3-6-year-old children in Peking city.
  
  
  METHODS
  This cross sectional study was conducted via an examination of the occlusal characteristics of 734 children combined with a questionnaire completed by their parents/guardians. The examination was performed by a single, previously calibrated examiner and the following variables were evaluated: presence or absence of deep overbite, open bite, anterior crossbite, posterior crossbite, deep overjet, terminal plane relationship of the second primary molar, primary canine relationship, crowding and spacing. Univariate analysis and multiple logistic regressions were applied to analyze the associations.
  
  
  RESULTS
  It was found that a short duration of breast-feeding (never or ≤ 6 months) was directly associated with posterior cross bite (OR = 3.13; 95% CI = 1.11-8.82; P = 0.031) and no maxillary space (OR = 1.63; 95% CI = 1.23-2.98; P = 0.038). In children breast-fed for ≤ 6 months, the probability of developing pacifier-sucking habits was 4 times that for those breast-fed for >6 months (OR = 4.21; 95% CI = 1.85-9.60; P = 0.0002). Children who were bottle-fed for over 18 months had a 1.45-fold higher risk of nonmesial step occlusion and a 1.43-fold higher risk of a class II canine relationship compared with those who were bottle-fed for up to 18 months. Non-nutritive sucking habits were also found to affect occlusion: A prolonged digit-sucking habit increased the probability of an anterior open bite, while a pacifier-sucking habit associated with excessive overjet and absence of lower arch developmental space.
  
  
  CONCLUSIONS
  Breastfeeding duration was shown to be associated with the prevalence of posterior crossbite, no maxillary space in the deciduous dentition and development of a pacifier-sucking habit. Children who had a digit-sucking habit were more likely to develop an open bite.
authors.affiliation: Department of Pediatric Dentistry, First Dental Center, Peking University School and Hospital of Stomatology, Postal address: Jia No.37 Xishiku Street, Xicheng District, Beijing, 100034, China. chenxiaox2007@126.com.
authors.forename: Xiaoxian
authors.initials: X
authors.lastname: Chen
authors.affiliation: Department of Pediatric Dentistry, Peking University School and Hospital of Stomatology, Beijing, 100081, China. summerinbeijing@vip.sina.com.
authors.forename: Bin
authors.initials: B
authors.lastname: Xia
authors.affiliation: Department of Pediatric Dentistry, Peking University School and Hospital of Stomatology, Beijing, 100081, China. gelh0919@126.com.
authors.forename: Lihong
authors.initials: L
authors.lastname: Ge
mesh_terms: D001903:Bottle Feeding; D001942:Breast Feeding; D002648:Child; D002675:Child, Preschool; D002681:China / Q000453:epidemiology; D003430:Cross-Sectional Studies; D005260:Female; D005386:Fingersucking / Q000009:adverse effects*; D006801:Humans; D007223:Infant; D007231:Infant, Newborn; D008297:Male; D008310:Malocclusion / Q000453:epidemiology*; D015999:Multivariate Analysis; D041361:Pacifiers / Q000009:adverse effects*; D015995:Prevalence; D013997:Time Factors