Imaging of the maxillary sinus

There are multiple methods for viewing the maxillary sinus including:
1. Panoramic radiography
2. Water's view
3. CBCT
4. MRI

Panoramic radiography has a focal trough that closely resembles the dental arch and so pathologies and abnormalities outside of this focal trough will not be properly imaged. Fluid levels often found in acute sinusitis are not well demonstrated in OPGs. Therefore MRI and CBCT 3D imaging are the gold standard for sinus imaging. We should therefore strive to detect abnormal symptoms and abnormalities on OPG radiographs and provide a diagnosis to avoid unneccessary specialist referrals and diagnostic tests.

-Inflammatory diseases
Sinus inflammatory conditions are most visible on an OPG when they are on the floor of the maxillary sinus most commonly the mucous retention phenomenon

-Mucous retention phenomenon
Smooth dome shaped swelling of the mucosa with homogeneous density
Rarely symptomatic
Requires no treatment
Has no relationship to sinus obstruction

-Antral mucocele:
Associated with osteal closure, complete sinus opacification, pain, jaw expansion, erosion of the antral outline.
Rare but serious and irregular erosion of the maxillary sinus requires referral to ENT or oncologist.

-Adjacent dental pathoses
Chronic dental abscesses can result in the loss of continuity of the lower border of the sinus and a related thickening of the sinus mucosa is occasionally evident.

-Benign cysts and neoplasms
Tend to displace the floor or wall of the sinus and can expand without obvious jaw expanson. Apical dental cysts can cause an upward displacement of the floor of the sinus but the cortical outline remains intact.
Dentigerous cysts have a similar effect to apical cysts on the floor of the sinus but they envelope the crown of an unerupted tooth. If the tooth is displaced it may appear to be suspended in the sinus.
Trabeulation in multilocular tumours e.g mycoma and ameloblastoma can sometimes be mistaken for septa within the sinus in the absence of noticable jaw expansion

-Other benign radioopacities
Keratinocystic odontogenic tumour results in a homogeneous radiolucency that is unilocular, multilocular, crenulated (Finely scalloped outline) and can occasionally envelope unerupted teeth. It tends to displace the sinus while producing little jaw expansion.
Benign tumours in general displace the sinus floor and expand inwards rather than outwards.
Ameloblastoma would display tooth displacement and external root resorption
OAF after extractions are only apparent when large and within the focal trough

-Dysplasic conditions affecting the maxillary sinuses
Fibrous dysplasia can cause partial or complete occlusion of the sinuse on the affected side. May arise in children and will be aparent by adolesence. Generally unilateral. Ground glass appearance and melds with surrounding bone.
Paget's disease can cause occlusion of the sinus but can affect both sides of the maxilla and is found in an ageing population. Cotton ball opaque sclerotic deposits and crosses the midline.

-Detection of maxillary sinus malignant neoplasia
When affecting the focal trough area, tends to result in erosion of bone. Primary carcinomas in the sinus are most commonly SCC, adenoid cystic carcinoma and adenocarcinoma. May also be a secondary tumour of the oral soft tissues or jaw and rarely metastasis from distant sites. OPGs can show signs of antral SCC especially when present on the posterior wall