Open-mouth odontoid view: what is done and what does it visualize?

Open-mouth odontoid view: what is done and what does it visualize?

• A. Mouth closed; CR through center of mouth; visualizes dens and C1–C2
• B. Mouth open; head in neutral; CR through center of mouth; visualizes dens and C1–C2
• C. Mouth open; head rotated 45 degrees; CR through center of mouth; visualizes C3–C4
• D. Mouth closed; head extended; CR through nasal passages; visualizes occipital condyles

Answer: (B)

Open-mouth odontoid imaging aims to bring the dens (odontoid process) into profile with the atlas and axis by allowing the mouth to stay wide open so the teeth don’t obscure the view. Positioning the head in a neutral attitude and directing the central ray through the center of the mouth ensures the beam passes through the dens and the C1–C2 region. This projection specifically visualizes the dens and the atlas–axis junction, which is essential for assessing odontoid fractures and alignment at C1–C2. If the mouth were closed, the dens could be obscured by teeth; if the head were rotated, the dens would be off-angle and distorted; directing the beam through the nasal passages would shift the view toward skull base structures rather than the upper cervical joints.

Open-mouth odontoid imaging aims to bring the dens (odontoid process) into profile with the atlas and axis by allowing the mouth to stay wide open so the teeth don’t obscure the view. Positioning the head in a neutral attitude and directing the central ray through the center of the mouth ensures the beam passes through the dens and the C1–C2 region. This projection specifically visualizes the dens and the atlas–axis junction, which is essential for assessing odontoid fractures and alignment at C1–C2. If the mouth were closed, the dens could be obscured by teeth; if the head were rotated, the dens would be off-angle and distorted; directing the beam through the nasal passages would shift the view toward skull base structures rather than the upper cervical joints.