Cephalometric Analysis Overview

Cephalometric Analysis Overview

• Lateral cephalograms provide critical information regarding craniofacial skeleton, soft tissue profile, dentition, pharynx, and cervical vertebrae.
• Cephalometric radiograph analysis is used for pre-treatment diagnosis, monitoring treatment progress and growth, and evaluating post-treatment results.

Measurement Techniques

• Measurements can be done via hand tracing or specialized software, such as Dolphin software.
• Important for accurate analysis is the use of a Cephalostat.

Anatomical Landmarks

• Validity is crucial; measurements should accurately represent anatomical structures.
• Measurements should be reproducible; consistency across repeated measures is essential.
• Some key landmarks:
  • Sella (S): midpoint of sella turcica in the median plane, located in sphenoid bone.
  • Nasion (N): most anterior point of the frontonasal suture in the median plane.
  • Point A: deepest midline concavity on maxilla between anterior nasal spine and prosthion.
  • Point B: deepest midline concavity on mandibular symphysis.
  • Pogonion (Pog): most anterior point of the bony chin.
  • Gnathion (Gn): most anteroinferior point on the chin symphysis.
  • Gonion (Go): intersection of ramus plane and mandibular plane.
  • Menton (Me): most inferior midline point on the mandibular symphysis.
  • Porion (P): superior point of external auditory meatus.
  • Orbitale (Or): lowest point in the inferior margin of the orbit.

Requirements for Quality Cephalometric Analysis

• Ensure natural head position during imaging.
• Use a millimeter ruler for accurate measurements.
• Patient must bite in centric occlusion (CO) for consistency.

Reference Lines

• Important reference lines include:
  • Sella-Nasion line
  • Frankfort line (horizontal between orbit and porion)
  • ANS to PNS line
  • Mandibular line (from Gonion to Gnathion)
  • Occlusal plane (derived from molars and premolars).

Malocclusion Assessment

• Determine if malocclusion is skeletal or dental using ANB angle:
  • Normal ANB (0-2 degrees) indicates no skeletal issues.
  • ANB greater than 2 suggests Class II skeletal pattern.
  • ANB less than 0 indicates Class III skeletal pattern.
• Identify which jaw (maxilla or mandible) is advanced.

Vertical Relation Analysis

• Normal SNMP = 33 degrees; values above indicate an open bite.

Dental Component Analysis

• Analyze dental compensation using specific incisor measurements:
  • Upper incisor to SN: 103 degrees.
  • Lower incisor to MP: 91 degrees.
  • Upper incisor to NA: 22 degrees (4 mm).
  • Lower incisor to NB: 25 degrees (4 mm).
• Evaluate proclination or retroclination based on measurements.

Additional Considerations

• Recognize that a cephalometric radiograph is a 2-D representation of 3-D structures.
• Be aware of potential errors in landmark identification and individual face variability.

Monitoring Growth

• Superimpose two cephalometric radiographs for growth monitoring.
  • Overall changes monitored via S-N line over sella.
  • Mandibular aspects checked through third molar follicle, symphysis border, dental canal, and anterior chin point.
  • Maxillary updates noted through root of the zygomatic arch.

Case Examples

• Class III cases of mandibular prognathism should be assessed through ANB and SNB relation adjustments, confirming prognathism with SN within normal limits and observing normal MP.
• Upper incisor measurements may indicate proclination, while lower incisor positioning could show retroclination.