ObjectiveObstructive sleep apnea (OSA) and periodontitis share risk factors, such as age, obesity, stress, and cardiovascular events, which have a bidirectional cause-effect relationship through systemic inflammation. Our objective was to determine the relationship between OSA and the periodontal condition and its associated local and systemic risk factors.Material and methodsThis was an observational case-control study involving 60 patients. Local oral risk factors and the systemic condition of each patient were evaluated. All patients underwent polysomnography for the diagnosis of OSA. Chi-squared, one-way ANOVA, and Bonferroni’s tests were performed.ResultsA higher percentage of patients with periodontitis had severe OSA (66.66%); however, no statistically significant association was found between the two pathologies (p= 0.290). In terms of systemic risk factors, an association was found between arterial hypertension and severe OSA (p= 0.038), and in terms of local factors, an association was found between the use of removable prostheses and severe OSA (p= 0.0273).ConclusionIn the general population, patients with periodontitis showed a higher prevalence of severe OSA. Obesity and hypothyroidism were the most prevalent systemic findings in patients with OSA and periodontitis. Arterial hypertension and osteoarthritis were found to be associated with severe OSA. The local risk factors associated with periodontitis and severe OSA were removable partial dentures and misfit resins.Clinical relevanceTo study the factors that can facilitate the progression of OSA and periodontitis, physicians and dentists should be advised to provide comprehensive care for patients with both pathologies.