ORIGINAL ARTICLE Association of breastfeeding and malocclusion in 5‐year‐old children: Multilevel approach Patrícia Corrêa-Faria 1 | Mauro Henrique Nogueira Guimarães de Abreu 2 | Lidia Moraes Ribeiro Jordão 1,3 | Maria do Carmo Matias Freire 1,3 | Luciane Rezende Costa 1,3 1 Dentistry Graduate Program, Faculdade de Odontologia, Universidade Federal de Goiás, Goiânia, GO, Brazil 2 Department of Community and Preventive Dentistry, Universidade Federal de Minas Gerais, Belo Horizonte, MG, Brazil 3 Department of Oral Health, Faculdade de Odontologia, Universidade Federal de Goiás, Goiânia, GO, Brazil Correspondence: Patrícia Corrêa-Faria, Av. Universitária Esquina com 1, Avenida s/n, Setor Universitário, Zip code: 74605- 220, Goiânia, Goiás, Brazil (patriciafaria.faria09@gmail.com). Background: Breastfeeding plays an important role in child health, including the development of normal dental occlusion, but large epidemiological findings on the association breastfeeding‐malocclusion are lacking. Aim: To investigate the association between the proportion of breastfed children in the city level and the prevalence of malocclusion in the primary dentition at age 5. Design: This cross‐sectional analysis used data from national population surveys on oral health and on breastfeeding practices. Data refer to 5278 5‐year‐old chil- dren and 44 Brazilian towns. Information on malocclusion and individual sociode- mographic characteristics were obtained from the 2010 Brazilian Oral Health Survey. Breastfeeding rates during the first year of life were extracted from the Breastfeeding Prevalence Survey in Brazilian Towns. Population sociodemo- graphic data were analysed as confounder. Multilevel Poisson analyses were per- formed. Results: Malocclusion prevalence was 63.3%. Towns exhibiting higher preva- lence of breastfeeding among 9‐ to 12‐month‐olds presented lower prevalence of malocclusion among children at age 5 (PR 0.98; 95% CI 0.98‐0.99). Conclusions: Lower prevalence of malocclusion among 5‐year‐old children was associated with a higher proportion of children breastfed at ages 9 to 12 months at a city level, regardless of sociodemographic factors. These findings highlight the importance of encouraging breastfeeding during a child's first year. KEYWORDS breastfeeding, child, malocclusion, multilevel analysis, preschool 1 | INTRODUCTION Malocclusions are frequent alterations among preschool chil- dren and may impact negatively their quality of life. 1 In addi- tion, this condition may track into mixed 2 and permanent dentition. 3 According to studies carried out in countries such as Germany 4 and China, 5 the prevalence of occlusal alter- ations in the primary dentition is high and may reach more than 80%. 5 Data from a nationally based epidemiological survey conducted in Brazil in 2010 revealed that about 68% of 5‐year‐olds presented dental or craniofacial alterations. Increased overjet, anterior open bite, and posterior crossbite were the most frequent alterations. 6 The aetiology of malocclusions is related to multiple factors, 7 including hereditary and environmental aspects. 8 In that sense, deleterious oral habits 9 and unfavourable socioeconomic characteristics have been associated with greater prevalence of malocclusion. Previous studies tend to agree on the role that nonnutritive sucking habits play on the occurrence of malocclusion in the primary Received: 4 May 2018 | Revised: 3 June 2018 | Accepted: 18 July 2018 DOI: 10.1111/ipd.12417 Int J Paediatr Dent. 2018;1–6. wileyonlinelibrary.com/journal/ipd © 2018 BSPD, IAPD and John Wiley & Sons A/S. Published by John Wiley & Sons Ltd | 1