Cephalometrics in Orthodontics: 3D vs 2D Radiographs
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Questions and Answers

What is the cephalometric landmark defined as?

  • Points used in evaluating soft tissue structures
  • Points used in evaluating three-dimensional measurements
  • Points used in evaluating growth and development
  • Points used in evaluating linear and angular measurements in 2D (correct)
  • Which landmark is defined as the center of Sella turcica?

  • PNS
  • Gnathion
  • Orbitale
  • Sella point (correct)
  • What is the PNS landmark in cephalometrics?

  • The chin
  • The center of Sella turcica
  • The anterior nasal spine
  • The most posterior point on the bony hard palate (correct)
  • Which landmark is described as the anteroinferior point on the contour of the bony chin symphysis?

    <p>Gnathion</p> Signup and view all the answers

    What does ANS stand for in cephalometrics?

    <p>Anterior Nasal Spine</p> Signup and view all the answers

    Which landmark represents the most inferior point on the symphysis of the mandible in the median plane?

    <p>Menton</p> Signup and view all the answers

    What is the angle of facial convexity defined as?

    <p>Angle between the glabellasubnasale line and SnPg' line</p> Signup and view all the answers

    In which gender is a more convex soft tissue profile considered esthetically pleasing?

    <p>Females</p> Signup and view all the answers

    What is the purpose of the Ricketts E-line in cephalometric analysis?

    <p>To assess the position of the upper lip relative to the nose</p> Signup and view all the answers

    Which cephalometric plane connects the midpoint of sella turcica with nasion?

    <p>SN Plane</p> Signup and view all the answers

    What landmarks does the Frankfort Plane pass through?

    <p>Porion and orbitale</p> Signup and view all the answers

    Which line represents the cranial base in cephalometric analysis?

    <p>Sella-Nasion line</p> Signup and view all the answers

    What is the intersection of the lateral radiographic image of the posterior border of the ramus with the base of the occipital bone called?

    <p>Articulare</p> Signup and view all the answers

    Which point is located at the most superior point of the external auditory meatus?

    <p>Porion</p> Signup and view all the answers

    What is the most inferoposterior point on the anterior margin of the foramen magnum called?

    <p>Ba</p> Signup and view all the answers

    Which landmark is described as the most prominent midline point in the midsagittal plane between the eyebrows?

    <p>Trichion</p> Signup and view all the answers

    Where is the point where the columella merges with the upper lip in the midsagittal plane located?

    <p>Subnasale</p> Signup and view all the answers

    What comprises the lower two-thirds in an ideal lower third facial structure?

    <p>Me’ to St</p> Signup and view all the answers

    Study Notes

    Cephalometrics in Ortho

    • Replacing 2D with 3D CBCT, allowing for a multi-aspect view (x, y, z format) of the entire craniofacial structure with one radiograph.

    Cephalometric Landmarks and Planes

    • Cephalometric landmarks are points used in precise evaluation of 2D measurements like length, width, or height.
    • Global acceptance of cephalometric landmark definitions and associated linear and angular measurements is essential for standardized classification and discussion of growth, development, and treatment outcomes.

    Hard Tissue Landmarks

    • Sella point (S): Center of Sella turcica.
    • Orbitale (Or): The lowest point on the inferior margin of the orbit.
    • ANS (Anterior Nasal Spine): Sharp median process formed by the forward prolongation of the two maxillae at the lower margin of the anterior aperture of the nose.
    • PNS (Posterior nasal spine): The most posterior point at the sagittal plane on the bony hard palate.
    • A point: The most posterior point on the curve of the maxilla between the anterior nasal spine and supradentale.
    • B point: The deepest point of the anterior alveolar bone recess of the mandible.
    • Pogonion (Pog): The most anterior part of the chin.
    • Gnathion (Gn): Most anteroinferior point on the contour of the bony chin symphysis.
    • Menton (Me): Most inferior point on the symphysis of the mandible in the median plane.

    Soft Tissue Landmarks

    • Convexity: The intersection of soft tissue nasion–subnasale line (N ′ Sn) and the subnasale–soft tissue pogonion line (SnPg ′).
    • The angle of facial convexity: Angle formed between the glabellasubnasale line (GSn) intersecting with the SnPg ′ line.
    • In females, a more convex profile is considered esthetically pleasing, while straighter profiles are generally preferred for males.

    Ricketts E-Line

    • Ricketts E-line (esthetic plane): Drawn from the tip of the nose to Pg ′.
    • Ideally, the upper lip is about 4 mm behind this reference line, while the lower lip lies about 2 mm behind it.

    Cephalometric Planes

    • Horizontal planes:
      • SN Plane: Connecting the midpoint of sella turcica with nasion, representing the cranial base.
      • Frankfort Horizontal Plane: Passing through porion and orbitale.
      • Maxillary Plane: Passing through anterior nasal spine and posterior nasal spine.
      • Occlusal Plane: Passing through occlusal surface of 1st molars and incisal edge.
      • Mandibular Plane: Passing through gnathion, pogonion, and menton.
    • Other points:
      • Gonion (Go): Midpoint of the angle of the mandible.
      • Articulare (Ar): Intersection of the lateral radiographic image of the posterior border of the ramus with the base of the occipital bone.
      • Basion (Ba): The most inferoposterior point on the anterior margin of the foramen magnum.
      • Glabella: The height of curvature of the bone overlying the frontal sinus.
      • Porion (Po): A point located at the most superior point of the external auditory meatus.
      • Pterygoid Point (Pt): Intersection of the inferior border of the foramen rotundum with the posterior wall of the pterygomaxillary fissure.

    Soft Tissue Landmarks

    • Trichion (Tri): Hairline.
    • Soft tissue Glabella: The most prominent midline point in the midsagittal plane between the eyebrows.
    • Subnasale (Sn): The point at which the columella (nasal septum) merges with the upper lip in the midsagittal plane.
    • Stomion (St): The contact point between the upper and lower lip at the mouth slit.
    • Soft tissue menton (Me’): The most inferior point on the soft tissue chin.
    • In an ideal lower third, subnasale to stomion (St) comprises the upper third, while menton to stomion (or the top of the lower lip) make up the lower two-thirds.

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    Description

    Learn about the advancements in cephalometrics with the use of 3D CBCT technology in orthodontics. Explore how 3D radiographs can replace multiple 2D radiographs and provide a comprehensive view of the craniofacial structure from multiple angles. Understand cephalometric landmarks and planes used for precise evaluation of 2D measurements.

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