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Mandible & TMJ Lecture. RT 233 Week 7. Hello class, This is my preliminary lecture, I may add more slides over the weekend. Please check back on Sunday evening for any revisions. Mandible. Mandible. Only movable bone in the skull Densest & largest facial bone 2 bones at birth
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Mandible & TMJ Lecture RT 233 Week 7
Hello class, • This is my preliminary lecture, I may add more slides over the weekend. Please check back on Sunday evening for any revisions.
Mandible • Only movable bone in the skull • Densest & largest facial bone • 2 bones at birth • Contains mental foramina
PA Mandible (rami) • Seated or Prone • Forehead and nose on IR • OML & MSP perpendicular to IR • CR perpendicular to exit acanthion
PA Mandible (rami) Radiograph • Mandibular rami and lateral portion of body are visualized • Entire mandible without rotation or tilt
PA Mandible (body) • Seated or Prone • Nose and chin on grid device or table placing mandibular symphysis parallel with plane of IR • AML & MSP perpendicular to IR • CR perpendicular to level of lips
PA Mandible (body) Radiograph • Contrast and density are sufficient to view body and rami • Sharp bony detail indicating no motion
PA Axial (rami)Mandible Positioning • Seated or Prone • Forehead and nose on IR • OML & MSP perpendicular to IR • CR 20- 25 cephalic, centered to exit acanthion
PA Axial (rami)Mandible Radiographs • TMJ and heads of condyles are visible through mastoid processes. • Condyloid processes are well visualized, slightly elongated. • Entire mandible with no rotation or tilt with adequate density
PA Axial (body)Mandible Positioning • Seated or Prone • Nose and chin on grid device or table placing mandibular symphysis parallel with plane of IR • AML & MSP perpendicular to IR • CR between TMJ’s, 30 cephalad.
PA Axial (body)Mandible Radiographs • TMJ’s just inferior to mastoid process • Symmetric rami • Adequate contrast and density
AP Axial – Towne Method • OML & MSP perpendicular to IR • CR 35-40 caudad • Centered to glabella midway between EAMS and angles of mandible • If IOML is used increase CR angle 7 degrees
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 • Seated, semiprone or semisupine • IPL perpendicular to IR • Mouth closed- teeth together • Extend neck, chin jutted forward • CR 25 degrees cephalic to pass through area of interest
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
Axiolateral Oblique Positioning for Body • Seated, semiprone or semisupine • IPL perpendicular to IR • Mouth closed- teeth together • Extend neck, chin jutted forward • Rotate pt’s head 30 degrees toward IR • CR 25 degrees cephalic to pass through area of interest
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
Axiolateral Oblique Positioning for Mandibular Symphysis • Seated, semiprone or semisupine • IPL perpendicular to IR • Mouth closed- teeth together • Extend neck, chin jutted forward • Rotate pt’s head 45 degrees toward IR • CR 25 degrees cephalic to pass through area of interest
Axiolateral Oblique Radiograph for Mandibular symphysis • No overlap of mentum by the opposite side of mandible • No foreshortening of the mentum region
Panorex Mandible • Explain how tube/image receptor move • IOML perpendicular • Stand straight, not jutting chin forward • Instruct pt to keep lips together and tongue on roof of mouth
Panorex Mandible Radiographs • Demonstrates teeth, mandible, TMJ’s • Density are uniform across image • No artifacts
AP Axial Temporomandibular • Supine or seated upright • Posterior teeth closed and in contact • For open mouth- wide as possible without chin jutted forward • OML perp to IR • CR 35 caudad, centered midway between TMJ’s. • Enters approx 3” above nasion
AP Axial TMJ Radiograph • No rotation • Minimal superimposition of petrosa on condyle in closed mouth • Condyle and TMJ below pars petrosa in open mouth
Axiolateral TMJ • Semiprone or seated • Center ½” anterior to EAM • Rest cheek on grid device • Rotate MSP approx 15 degrees toward IR • IPL perpendicular • CR 15 caudad exiting through TMJ closest to IR about 1 ½ “ superior to upside EAM
Axiolateral TMJ Radiograph • TMJ • Condyle lying in mandibular fossa in closed mouth • Condyle lying inferior to articular tubercle in open mouth