For well over 100 years, it has been appreciated that maxillary dental infections can cause sinusitis. This insight has been largely overlooked with the advent of functional endoscopic sinus surgery (ESS) and its emphasis on the osteomeatal complex. We review several recent case series and reviews of odontogenic sinusitis that characterize and discuss emerging diagnostic modalities in odontogenic sinusitis. In recent publications on odontogenic sinusitis, up to 40% of chronic bacterial maxillary sinus infections are attributed to a dental source, which is far higher than the previously reported incidence of 10%. Plain dental films and dental evaluations frequently fail to detect maxillary dental infection that can be causing odontogenic sinusitis. However, sinus computed tomography (CT) or Cone Beam Volumetric CT (CBVCT) are far more successful in identifying dental disease causing sinusitis. The microbial pathogens of odontogenic sinusitis remain unchanged from earlier reviews; however, the clinical findings in odontogenic sinusitis are better described in recent reviews. Successful treatment of odontogenic sinusitis requires management of the odontogenic source and may require concomitant or subsequent sinus surgery. Odontogenic sinusitis is frequently recalcitrant to medical therapy and usually requires treatment of the dental disease. Sometimes dental treatment alone is adequate to resolve the odontogenic sinusitis and sometimes concomitant or subsequent ESS is required. Evaluation of all patients with persistent chronic rhinosinusitis (CRS) should include inspection of the maxillary teeth on CT scan for evidence of periapical lucencies. Unilateral recalcitrant disease associated with foul smelling drainage is especially characteristic of odontogenic sinusitis. High-resolution CT scans and CBVCT can assist in identifying dental disease.