ABO Cephalometric Analysis and Radiographic Interpretation 1 — Questions and Answers
Question 1: What is the normal value for the SNA angle in cephalometric analysis?
- 76°
- 79°
- 82° (Correct answer)
- 88°
Correct answer: 82°
The normal SNA angle is 82° (±2°), representing the anteroposterior position of the maxilla relative to the cranial base.
Question 2: Which cephalometric landmark is defined as the most posterior-superior point of the pituitary fossa?
- Nasion
- Articulare
- Sella (Correct answer)
- Porion
Correct answer: Sella
Sella (S) is located at the center of the sella turcica and serves as the origin of the sella-nasion reference line.
Question 3: The Frankfort Horizontal plane is constructed between which two cephalometric landmarks?
- Sella to Nasion
- Porion to Orbitale (Correct answer)
- ANS to PNS
- Gonion to Menton
Correct answer: Porion to Orbitale
The Frankfort Horizontal is drawn from Porion (superior border of external auditory meatus) to Orbitale (lowest point of the orbital rim).
Question 4: Which cephalometric analysis first introduced the concept of measuring facial convexity angle to evaluate the skeletal profile?
- Steiner analysis
- Ricketts analysis
- Downs analysis (Correct answer)
- McNamara analysis
Correct answer: Downs analysis
Downs analysis (1948) introduced the facial convexity angle, measuring the convexity of the face from Nasion-A point-Pogonion.
Question 5: In standard cephalometric analysis, the mandibular plane is most commonly constructed from which landmarks?
- Gonion to Menton (Correct answer)
- Articulare to Pogonion
- Sella to Nasion
- ANS to Menton
Correct answer: Gonion to Menton
The mandibular plane is typically drawn from Gonion (Go) to Menton (Me), representing the inferior border of the mandible.
Question 6: What is the normal range for the FMA (Frankfort-Mandibular Plane Angle) in Tweed's analysis?
- 12–18°
- 19–24°
- 25–30° (Correct answer)
- 31–38°
Correct answer: 25–30°
The normal FMA in Tweed's analysis is approximately 25° (±5°), with 25–30° representing a normal vertical skeletal pattern.
Question 7: An ANB angle of +6° in a patient most likely indicates which skeletal classification?
- Class I skeletal relationship
- Class II skeletal relationship (Correct answer)
- Class III skeletal relationship
- Normal bimaxillary protrusion
Correct answer: Class II skeletal relationship
An ANB angle greater than +4° indicates a Class II skeletal discrepancy, with the maxilla positioned anteriorly relative to the mandible.
ABO Cephalometric Analysis and Radiographic Interpretation 1
What is the normal value for the SNA angle in cephalometric analysis?