This article summarizes how to diagnose common and nuanced cases of odontogenic sinusitis (ODS) through a collaborative approach between otolaryngologists and dental specialists, with a heightened focus on the role of otolaryngologists in the diagnostic process. A critical part of the diagnostic framework is that otolaryngologists must confirm the infectious sinusitis but also suspect ODS to ensure he or she refers the patient to a dental specialist to confirm or refute ipsilateral infectious maxillary dental pathology. To confirm the purulent sinusitis of ODS, nasal endoscopy is most critical. Computed tomography imaging is an important part of the workup.