RESUMO
Objective: To determine the prevalence of bruxism, associating it with mouth breathing in preschool children in Florianopolis, Brazil. Material and Methods: Clinical examination and questions to parents/guardians of 429 children aged 2-5 were conducted. The clinical examination was performed by three calibrated examiners to register the presence of tooth wear on incisors and molars. The questions were related to sleep bruxism (teeth grinding) and mouth breathing. For determinate diagnosis, were "possible" bruxism by the American Academy of Sleep Medicine and "probable" bruxism, whereas the Item Response Theory was employed for mouth breathing. To determine the associations, a Chi-square test and Fisher exact test with a standard error of 5% and 95% interval confidence were applied. Results: The clinical examination revealed bruxism in 8.2%, whereas the parental report revealed bruxism in 17.2%. When clinical examination was associated with the parent's report, bruxism was present in 2.1%. Among the non-clinical variables, the most prevalent changes included: child presenting a regular stuffy nose (19.6%), followed by child is always open-mouthed (16.1%). A significant statistical association between bruxism and age was obtained (p<0.05), the age group with prevalence of 4 and 5 years old with 68.9%. There was no mouth breathing association with the presence of bruxism (p>0.05). Conclusion: Bruxism was prevalent for children aged 4-5 and bruxism had no association with mouth breathing.