DDS 6234 / DH 3234 Air cavities within facial bones lined by mucoperiosteum (1 mm thick) Unknown function: humidification and heating, aid in olfaction, reduction of cranium weight, addition of resonance to voice, protection and insulation of cerebrum and orbits, evolutionary unwanted space Maxillary Ethmoid Frontal Sphenoid Mastoid Hypoplasia (8%), aplasia rare Ostium at the superior aspect of the medial wall of the max. sinus Close proximity to teeth apices Jaw pathology can extend in the sinus Max. pathology can give symptoms from teeth Proximity to vital structures: orbits, pterygo-palatine fossa, brain Sinusitis Acute Chronic Polyps Mucous retention phenomenon (MRP) Mucocele Conventional Radiography intraoral (periapical, occlusal) extraoral (pan, Waters’, Lateral and PA skull) CT MRI Acute, chronic and recurrent Allergic Infectious Dental sources Periapical lesions Traumatic extractions (Oro-antral fistula) Often a complication of common cold Nasal discharge or pharyngeal drainage Pain, tenderness over involved sinus Teeth may be sensitive to percussion Fever, chills, malaise, elevated leukocyte count Thickening of mucosal lining Cloudy appearance in periapical or panoramic Bony erosion Fungal infection Carcinoma Chronic infection Typically sequel of an unresolved acute infection No extreme symptoms except in case of acute exacerbations Might be a complication of anatomic derangements, allergic rhinitis, asthma, cystic fibrosis, dental infections Radiodensity (due to mucosal thickening and accumulation of secretions) Uniform or polypoid Shape/architecture/extent Air-fluid level Effects on adjacent structures Mucosal thickening, sclerosis of bony wall Sinus size normal or decreased Facial pain, pressure, nasal obstruction, headache, dental pain Pus due to infection Blood from trauma Straight superior surface with tapered edges (meniscus) Always horizontal Multiple sinus opacification Expansion of sinus, possible erosion of border Unilateral or bilateral (R>L).  Ethmoid>maxillary>frontal>sphenoid Mostly young adults. M>F Nasal obstruction, facial deformity, diplopia Hypertrophy of inflamed mucosa in irregular folds Single or multiple Can be locally destructive D/D from mucous retention cysts/ phenomenon Usually asymptomatic Dome-shaped, uniform, well defined radiopacity Location and size varies Can be superimposed over root apices D/D from polyps, cysts, tumors Expanding, destructive lesion Starts with an MRP and a blocked ostium Radiating pain, sensation of fullness, swelling Sinus opacification, expansion and destruction of the sinus borders Rare in maxillary sinus 90% in ethmoid or frontal