Paranasal Sinuses Flashcards
2 purposes of imaging the maxillary sinuses
- To verify the integrity of the sinus walls
- To identify the presence of disease
2 ways sinus walls may be compromised
- Cysts and benign tumors –> displace walls
- Malignant tumors –> destroy walls
9 functions of the maxillary sinus
- Air conditioning (heating and humidification)
- Acting as an air reservoir
- Ventilation
- Aiding in olfaction
- Reductoin in weight of the cranium
- Addition of resonance to the voice
- Protection
- Insulation of the cerebrum and orbits
- Participation in formation of the cranium
How to distinguish a cyst in the posterior maxilla from a normal maxillary sinus
Presence of nutrient canals in the walls of the maxillary sinus (radiolucencies)
When does pneumatization mostly occur?
Following extractions
2 problems with pneumatization
Often limits implant placement
Often combined with resorption
Define pneumatization
The presence or development of air-filled cavities in a bone
Radiographic appearance of hypoplasia of the sinus
The hypoplastic sinus appears more radiopque because there is more bone and less air in the maxilla
Describe sinus septa
Radiopaque lines within the sinus, usually indicating incomplete divisions
Describe hyperostosis (exostosis)
Bony projection attached to the wall of the sinus, appearing as radiopacities within the sinus. Can have the appearance of retained root tips but have no ligament space and no lamina dura
6 types of projections to image the paranasal sinuses
- Periapical radiograph
- Maxillary lateral occlusal
- Panoramic
- Plain films
- CT
- MRI
4 types of plain films to visualize the sinuses
- Waters
- Posteroanterior - Caldwell
- Lateral
- Submentovertex
4 observations when imaging the maxillary sinus using Waters technique in plain film
- Lateral wall
- Medial wall
- Posteroinferior aspect obscured by the teeth
- Roof appears as 2 lines
- Superior = inferior orbital rim
- Inferior = floor of the orbit
Describe what can be seen on plain film with a posteroanterior view
- Midline and posterior facial structures displayed well
- Frontal sinus
- Ethmoid sinus
- Nasal cavity
- Lower half not seen well due to superimposition of the petrous ridge
Describe what can be seen on plain film with a submentovertex view
- Maxillary sinus
- Lateral wall
- Medial wall
- Sphenoid sinus
Describe what can be seen in axial CT images
Anterior wall
Posterior wall