Cephalometric Analysis in Orthodontics

What is Cephalometrics?

• Cephalometrics refers to the quantitative evaluation of cephalograms, or the measuring and comparison of hard and soft tissue structures on craniofacial radiographs.
• Cephalometric analysis helps to confirm or clarify the clinical evaluation of the patient and provides additional information for decisions concerning treatment.

Why do we need Cephalometrics in Orthodontics?

• A lateral cephalogram shows a 2D view of the anteroposterior position of teeth, the inclination of the incisors, the position and size of the bony structures holding the teeth, and the cranial base view of the upper respiratory tract.
• We can assess skeletal or dental malocclusion, position of the incisors, position of the jaws relative to each other and the cranial base, and compare pre/post-treatment positions.
• Soft tissue is also involved in the anomaly, and changes with growth and development can be assessed.

Cephalometric Landmarks and Planes

• Cephalometric landmarks are points used in precise evaluation of 2D measurements like length, width, or height.
• Hard tissue landmarks include:
  • Sella point (S): Center of Sella turcica
  • Orbitale (Or): The lowest point on the inferior margin of the orbit
  • Anterior Nasal Spine (ANS): Sharp median process formed by the forward prolongation of the two maxillae
  • Posterior Nasal Spine (PNS): 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
  • 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
  • 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
• Convexity: Intersection of soft tissue nasion–subnasale line (N′Sn) and the subnasale–soft tissue pogonion line (SnPg′)

Cephalometric Analysis

• Ricketts E-Line: The esthetic plane is drawn from the tip of the nose to Pg′
• In females, a more convex profile is considered esthetically pleasing, whereas straighter profiles are generally preferred for males.

Cephalometric Planes

• Horizontal planes:
  • SN Plane: Connects the midpoint of sella turcica with nasion
  • Frankfort Horizontal Plane: Passes through porion and orbitale
  • Maxillary Plane: Passes through anterior nasal spine and posterior nasal spine
  • Occlusal Plane: Passes through occlusal surface of 1st molars and incisal edge
  • Mandibular Plane: Passes through the inferior border of the mandible