A patient has persistent purulent nasal discharge and facial pain predominantly in the morning worsened by bending forward, following a recent dental procedure involving the upper left premolar. CT paranasal sinuses shows left maxillary sinus opacification with a periapical lucency in the adjacent second premolar. The most likely diagnosis and its aetio-pathogenesis are:

• A Chronic rhinosinusitis — CRS with nasal polyps, not related to dental cause
• B Fungal sinusitis (mycetoma) — dental metallic material providing a nidus
• C Odontogenic sinusitis — maxillary sinusitis arising from periapical infection of the upper dentition (roots of upper molars/premolars project into the sinus floor) ✓
• D Osteomyelitis of the maxilla with secondary sinus involvement

Explanation

Odontogenic sinusitis accounts for approximately 10–12% of all maxillary sinusitis cases. The roots of upper molar and premolar teeth (particularly the second and third molars, and first and second premolars) may project directly into the floor of the maxillary sinus with only a thin membrane separating them. Periapical infection, failed root canal treatment, or dental implants can breach this barrier, seeding bacteria (often anaerobic, including Fusobacterium, Prevotella, Bacteroides) into the sinus. Odontogenic sinusitis characteristically involves unilateral maxillary sinus with foul-smelling discharge, does not respond to standard antibiotic therapy, and requires combined dental treatment (tooth extraction/apicoectomy) with FESS.

Reference: Dhingra Diseases of Ear, Nose and Throat, 7th ed.

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Written and medically reviewed by the StethoPrep medical team.