MANDIBLE RT 233

MANDIBLE ANATOMY rami coronoid process body mental foramen condyle mental symphysis alveolar process mentum mental protuberance

Mandible Mandible starts out as two ossification centers, fuses into one bone sometime during the first year of life

Mandible

Mandible Indications for x-ray Fractures Neoplastic Processes Inflammatory Processes 2nd most commonly fractured bone of face • most mandibular fractures occur at a single location • multiple fractures and/or TMJ dislocations are common • majority occur in body – often associated w/ a contralateral condylar process fracture http Most mandibular fractures are a result of MVA, second most common cause-fist fight

Mandible

Essential Projections: Mandible PA – rami PA-body PA axial – rami PA axial-body Axiolateral obliques for rami, body, symphysis

Additional Projections SMV AP Axial (Townes) True Lateral

PA Mandible (for rami)   Entry point for CR is roughly just distal to occiput Collimate to include TEA, lower mandible

Mandible-PA (for rami) Mandibular rami Lateral portion of body are visualized Demonstrate the entire mandible without rotation or tilt Will show medial or lateral displacement of fractures

PA Mandible Rami- Diagram

Projection??

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Mandible-PA (for body)   Very similar to Waters but not as much extension, use LML Entry point for CR is base of occiput

Mandible-PA (for body) Contrast and density are sufficient to view body and rami Sharp bony detail indicating no motion

Projection? Identify labels:…..

Mandible-PA Axial (for rami)   CR entry is close to C7, T1, collimate to include EAM

Mandible- PA Axial (for rami) Heads of condyles are visible through mastoid processes. Condyloid processes are well visualized, slightly elongated. Proper Density No rotation or tilt

PA Axial (body) Mandible Positioning   CR passes thru EAMs, exits LML, near acanthion

PA Axial (body) Mandible Radiographs TMJ’s just inferior to mastoid process Symmetric rami Adequate contrast and density

AP Axial – Towne Method   IF the area of interest is the TM fossae angle the CR 40 degrees to the OML to reduce superimposition of the TM fossae and mastoid portions of the temporal bone.

AP Axial- Towne Method Radiograph Demonstrates condyloid processes symmetrically Clear visualization of TMJ fossae and condyle relationship Minimal SI of TM fossae and mastoid portions

Axiolateral Oblique Positioning for Ramus   Center downside to cassette, off-set cassette if needed for CR angle. Enter CR just below upside Body, near 1st molar

Axiolateral Oblique Radiograph for Ramus No overlap of ramus by opposite side of mandible No elongation or foreshortening of ramus No superimposition of ramus by c-spine Note foreshortening of body

Axiolateral Oblique Positioning for Body   Place chin and cheek on long axis of cassette/Bucky Keep shoulders depressed, keep body near Bucky, If needed, tilt head toward bucky, decrease CR angle correspondingly

Axiolateral Oblique Radiograph for Body No overlap of body by opposite side of mandible No elongation or foreshortening of body No superimposition of body by c-spine Note overlap of Hyoid Bone

Axiolateral Oblique Positioning for Mandibular Symphysis  

Axiolateral Oblique Radiograph for Mandibular symphysis No overlap of mentum by the opposite side of mandible No foreshortening of the mentum region

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Panorex Mandible  

Panorex Mandible Radiographs Demonstrates teeth, mandible, TMJ’s Density are uniform across image No artifacts