- Acute sinusitis is an acute bacterial or viral infection of the paranasal sinuses.
- Main causes: upper respiratory tract infection, trauma, oro-antral joint, dental infection, nasal defect and allergic mucosal edema.
- Radiographic features: air-liquid level, air bubbles, mucosal thickening or complete opacification of the sinus.
- Chronic sinusitis: The inflammation of the sinuses has been present for more than 3 months.
- Main causes: persistent antral infection, persistent presence of a foreign body or an oro-antral connection.