Maxillary sinusitis is an acute or chronic inflammation of the maxillary sinus which is caused by fungal, viral, allergic, or bacterial rhinitis (Ferguson, 2014). Odontogenic maxillary sinusitis [OMS] is resulted from either iatrogenic injury to the sinus floor after a dental procedure or chronic maxillary dental disease untreated (Craig et al., 2020). Moreover, further studies highlighted that 45-75% of the unilateral maxillary sinus membrane thickening and opacification on the CT (Troeltzsch et al., 2015, Matsumoto et al., 2015, Turfe et al., 2019), and 25-40% (Albu and Baciut, 2010, Melén et al., 1986) of the maxillary sinusitis are resulted from odontogenic disease. Various odontogenic pathologies can cause OMS; namely, periodontitis, oroantral fistula, endodontic disease, and periimplantitis. Moreover, Abrahams and others (Abrahams and Glassberg, 1996) showed 60% of patients that have diseases in maxillary posterior teeth, exhibit pathologies in their maxillary sinuses. Selden described or referred to the spread of endodontic disease into the maxillary sinus as endo-antral syndrome (Selden, 1974, Selden, 1989, Selden, 1999).
