Introduction Sleep bruxism is an unusual orofacial disorder affecting both children and adults. Its consequences include temporomandibular disorder, muscle pain, periodontal problems, tooth wear and tooth loss. Its aetiology remains unclear, and a multifactorial nature has been attributed to pathophysiological, psychological and morphologic aspects. Most studies carried out so far involve adults and few have investigated younger groups. Hence this study aimed to assess the association between stress levels, personality traits and sleep bruxism in children.

Methods A population-based case-control study (proportion of 1:2) was carried out involving 120 children with sleep bruxism and 240 children without this disorder aged between 7 and 11 years. The sample was randomly selected from schools in the city of Belo Horizonte, Brazil. The following instruments were employed for the data collection: questionnaire administered to parents; Child Stress Scale (CSS); and Neuroticism and Responsibility scales of the Big Five Questionnaire for Children (BFQ-C). Psychological tests were administered and evaluated by psychologists. Sleep bruxism was diagnosed from parents' reports. The χ² test, binary and multivariate logistic regression were applied for the statistical analysis.

Results In the adjusted logistic model, children with a high level of stress due to psychological reactions (OR=1.8; 95% CI 1.1 to 2.9) and high sense of responsibility (OR=1.6; 95% CI 1.0 to 2.5) had a nearly twofold greater chance of having sleep bruxism in comparison to those with low levels of these psychological traits.

Conclusion High levels of stress and responsibility are associated factors for the development of sleep bruxism among children.