What's the mandibular plane angle? What's the significance of a high vs low angle?
angle formed from the mandibular plane (Go - Gn) and the anterior cranial base (S-N). Mean is 32 degrees.
High: class II, VME, ant open bite
Low: vertical deficiency, deep bites
What's the major difference between the Steiner analysis and the Witt's appraisal?
- Steiner compares the AP position of the maxilla & mandible to the cranial base. Witt's is a linear measurement of the max & mand NOT influenced by the cranial base.
Whats the Witts appraisal?
Lines drawn from A to the OP (occlusal plane) and B to OP. These two points should have the AO 1mm ahead in males and coincident in females. Large discrepancies might require surgery vs ortho alone.
What's the McNamara analysis for maxillary incisor position?
vertical line drawn through A point and parallel to N, which is perpendicular to FH. The facial surface of the max central incisor should be 4-6mm ahead.