Both periodontal diseases (PDs) and obstructive sleep apnoea (OSA) are highly prevalent disorders with global impact, associated with a large burden at individual patient and health system levels. These disorders often co‐exist, but there is growing evidence that the association between the disorders goes beyond an overlap between two highly prevalent diseases that have shared risk factors. Evidence suggests a potential causal relationship, although further research is required to verify this. Regardless of any causal relationship, the co‐existence of these disorders is important to recognize since they may act in combination to heighten health risks, particularly cardiovascular risk. Thus, dentists have an important role in screening for OSA in patients presenting with PDs, and similarly, they need to evaluate periodontal health in patients requiring treatment for OSA. Here we provide a narrative review of the association between PDs and OSA to raise awareness among clinicians and promote multidisciplinary collaborations that aim at an evidence‐based and effective management of such patients.