EFFICACY OF TEMPORARY FIXED RETENTION FOLLOWING ...

1. ANB, A Point to Nasion to B Point angle: The inferior angle formed at the
junction of the Nasion-A Point line and the Nasion-B Point line (Figure 3-13).
2. AOBO: The linear distance between two points along Downs’ occlusal plane
(Downs 1948) obtained from the intersection of a perpendicular line from
point A and from point B to the occlusal plane (Figure 3-14). This variable is
also referred to as the Wits appraisal (Jacobson 1975, 1976). In the present
study, Downs’ occlusal plane was used to calculate AOBO, even though
Jacobson promoted the use of the functional occlusal plane.
3. DOP, Downs’ Occlusal Plane: The line that bisects the maxillary and
mandibular incisal overbite and the most anterior occlusal contact of the
maxillary and mandibular first molars (Downs 1948).
4. FMA, Frankfort Mandibular Plane Angle: The anterior-inferior angle formed
at the junction of the Frankfort Horizontal plane and the mandibular plane
(Figure 3-15). Mandibular plane is defined by two landmarks, namely
anatomic Gonion and Menton.
5. FMIA, Frankfort Mandibular Incisor Angle: The posterior-inferior angle
formed between the Frankfort Horizontal plane and the long axis of the
mandibular central incisor (Figure 3-16).
6. IMPA, Incisor Mandibular Plane Angle: The posterior-superior angle formed
at the junction of the mandibular plane and the long axis of the mandibular
central incisor. The long axis of the mandibular incisor is defined by Ii and L1
apex (Figure 3-17).
7. SNA, Sella-Nasion A Point angle: The posterior inferior angle formed at the
junction of the Sella-Nasion plane and the Nasion-A Point plane (Figure
3-18).
8. SNB, Sella-Nasion B Point angle: The posterior inferior angle formed at the
junction of the Sella-Nasion plane and the Nasion-B Point plane (Figure 3-19).
9. Z angle: The inferior angle formed at the intersection of the Frankfort
Horizontal line and the profile line (Merrifield 1966), where the profile line is
defined by Pronasale and either Li or Ls depending on which lip in more
protrusive (Figure 3-20).
10. UL, Upper Lip: The millimeter measurement of the horizontal thickness of
the upper lip, recorded from Prosthion to the most anterior point on the
vermilion border of the upper lip (Merrifield 1966; Figure 3-21).
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