Dento- alveolar or dental structural diseases that affect the floor of the maxillary sinus can cause maxillary sinusitis which is known as odontogenic maxillary sinusitis (OMS). Many treatment protocols have been documented to treat OMS. However, There is no unanimity among clinicians on how and who should treat OMS, whether is it otolaryngologist, oral/maxillofacial surgeons, or dentist. Therefore, this study will be will be enrolled to evaluate the efficacy of the Single-step Functional Sinus endoscopy and trans-oral surgery in the management of maxillary sinusitis raised from Odontogenic origin via Department- integrated therapy.