Objective To investigate the association between probable sleep bruxism (PSB) and associated factors in schoolchildren. Materials and methods A case-control study was conducted with a representative sample of 320 schoolchildren aged 8 to 10 years. The case group (160 children with PSB) and the control group (160 children without PSB) were matched for sex and age at a proportion of 1:1. Information on audible characteristics of PSB, harmful oral habits, and socio-demographic characteristics as collected through questionnaires answered by the parents/caregivers. The family functioning of children was measured through The Family Adaptability and Cohesion Evaluation Scales (FACES III). Mothers self-administered the Lipp Stress Symptoms Inventory (LSSI) for adults to measure mothers’ stress and the children filled out the Child Stress Scale (CSS) to measure the children stress. Data analysis used descriptive and logistic regression analyses ( p  < 0.05). Results Among the children with stress, 67.3% had PSB. Children with stress (OR = 2.22, 95% CI 1.18–4.19), those with a history of nail biting (OR = 2.22, 95% CI 1.39–3.55), and biting objects (OR = 1.77, 95% CI 1.09–2.87) were more likely to have PSB. Conclusion Childhood stress and a history of nail biting or biting objects are important signs to be considered in schoolchildren with PBS. Clinical relevance These results alert that the PBS might be a sign of stress and other psychological problems such as tension and anxiety related to the presence of harmful oral habits. Furthermore, the results could help in the targeting of anamnesis, improved prevention and treatment strategies for sleep bruxism which should involve an interdisciplinary approach.