Mandible largest, densest bone of face 10 17 2012 home ed

PA Mandible

Lateral Mandible

Mandible is one of two non-paired bones of the face What is the other? If you said Occipital- you are wrong! That is a cranial bone! Vomer is other non-paired facial bone!

Basic Routine Projections for Mandible PA Bilateral Axiolateral Obliques SMV (optional)

Notice- there is no lateral projection- why not? Two halves of mandible would be superimposed-thus obscuring information for both sides.

Mandible-PA - Ramus

Mandible-PA-Ramus (General survey) Similar to a PA skull-nose and forehead against IR CR- 0 Degrees Exit at tip of nose (acanthion) 8x10 cassette, collimated (body and mentum superimposed on spine)

Evaluation Criteria - PA Mandible Mandibular body and rami symmetric include entire mandible collimate Interpupillary line horizontal midsag.plane perpendicular

Dental Dosage Average person in US is exposed to about 360 mrem per year from background sources Full mouth series of  dental x rays (18 intraoral exposures) = 36 mrem 1 set of dental x-rays = 1/10th background radiation average person is exposed to yearly Panorex film = 4 mrem or 1/90th yearly back. radiation

Panoramic tomography unit

Mandible-PA - Ramus

Mandible-PA Ramus Similar to PA skull-nose and forehead against IR CR- 0 Degrees Exit at tip of nose (acanthion) 8x10 cassette, collimated (body and mentum superimposed on spine)

Evaluation Criteria - PA Mandible Include entire mandible Mandibular body and rami symmetric Interpupillary line horizontal midsag.plane perpendicular Collimated

PA Mandible-Body Similar to PA for Ramus, except chin and nose against IR 0 degree CR angle

PA Mandible -Body Ramus Mentum Body Angle

PA - Body PA - Ramus

A pretty decent AP mandible can be obtained by doing C-spine odontoid

Mandible- axiolateral oblique Both left and right oblique projections must always be performed! Blow to one side of jaw transfers force to opposite side, possibly breaking that side, not necessarily fracturing side of impact

Mandible- axiolateral obliques – 3 variations Ramus (lateral) Body (30 degrees internally rotated) Symphysis (45 degrees internally rotated) CR angled up 25 degrees in all projections!

Mandibular axiolateral obliques Ramus Body Symphysis A B C

Mandibular Axiolateral oblique for Ramus Head true lateral CR angled 25 degrees up extend chin to avoid superimposition on spine

Axiolateral oblique-Ramus TMJ A CONDYLE B CORONOID C RAMUS D BODY E ANGLE F

Axiolateral oblique - Mandibular Body Similar to ramus oblique, but rotate head 30 degrees to IR (mand. Body of interest will be parallel to IR) CR 25 degrees up through area of interest

Axiolateral oblique-mandibular body Evaluation criteria -no overlap of body by opposite body no cervical spine superimposition no distortion of body Coronoid A B C D E Ramus Body Hyoid Angle

Mandibular Axiolateral oblique - symphysis No overlap of mentum no foreshortening (spine will overlap body)

Mandible-axiolateral oblique LAO LPO Shoulder super-imposition problem!

Mandible-axiolateral oblique (tip!) Why struggle to get patient into zero tilt lateral, and then angle 25 degrees up? Use tilted head to your advantage! tilt of head + CR angle 25 degrees

Mandible -SMV (optional) For visualizing mandibular body and coronoid & condyloid processes of rami

Mandible -SMV Similar to skull, but collimated to anterior portion of cranium IOML parallel to IR (tilt cassette forward if possible) CR Perpendicular to IOML, midway between angles of mandible

SMV- alternate projection

Mandible- SMV Evaluation Criteria Distance between lateral border of skull and mand. Equal on both sides condyles anterior to pars petrosae Symphysis extendng to anterior border of face Symphysis A Body B Coronoid process C Ramus D Condyle E F Petrous ridge

Hyoid Bone! What is the only bone of the human body that does not articulate with any other bone?

Hyoid Bone Attaches from the styloid processes of temporal bone to tongue No views to demostrate

REVIEW A- Coranoid process B- mandibular fossa C- neck of condyle D- Condyle E- condylar process F- Ramus G- Gonion H- Body I-Alveolar process