Comparison of Activator-Headgear and Twin Block Treatment Approaches in Class II Division 1 Malocclusion

Table 1

Cephalometric variables used in the study.

Number	Variable	Unit	Description
1	NSBa	°	Cranial base angle expression of the flexion of the cranial base (nasion-sella-basion)
2	SNA	°	Angle of anterior part of cranial base (S-N) and point A (subspinale) on maxilla
3	SNB	°	Angle of anterior part of cranial base (S-N) and point B (supramentale) on mandible
4	ANB	°	Angle between point nasion and point on maxilla and mandible, basal sagittal relation between the jaws
5	A-NPg	mm	The shortest distance from A point to the facial plane (N-Pg), expression of the skeletal convexity of the face
6	NL/NSL	°	Angle between the nasal line (anterior to posterior nasal spine ANS-PNS) and the nasion-sella line, expression of the tilting of the maxilla relative to the anterior cranial base
7	MP/NSL	°	Angle of mandibular plane (Go-Me) relative to the anterior cranial base
8	MP/NL	°	Angle of mandibular plane (Go-Me) and nasal line
9	FA/NBa	°	Lower angle between the facial axis (pterygoid point-gnathion) and the nasion-basion line, expression of the growth direction of the chin and the relationship, facial height and depth
10	UFH	mm	Upper facial height (middle third of the face), distance from nasion point to spina nasalis anterior measured perpendicular to Frankfort horizontal (FH)
11	LFH	mm	Lower facial height (lower third of the face), distance from spina nasalis anterior to menton measured perpendicular to FH
12	UFH/LFH	%	Upper to lower facial height ratio
13	Co-A	mm	Distance from condylion to A point; measurement of the effective length of midface
14	Co-Gn	mm	Distance from condylion to gnathion; measurement of the effective length of mandible
15	Max Mand diff	mm	Maxillomandibular differential length, the difference between the effective mandibular length (Co-Gn) and the effective midface length (Co-A): gives an indication of the sagittal discrepancy between maxilla and mandible
16	−1/MP	°	Superoposterior angle of lower incisor long axis and mandibular plane
17	+1/NSL	°	Inferoposterior angle of upper incisor long axis and a nasion-sella line
18	−1/A-Pg angle	°	Angle between the long axis of the lower incisor and A-Pg line
19	+1/A-Pg angle	°	Angle between the long axis of the upper incisor and A-Pg line
20	−1/A-Pg distance	mm	Distance from the midpoint of the incisal edge of the most prominent mandibular incisor to A-Pg line, expression of the protrusion of the lower incisors
21	+1/A-Pg distance	mm	Distance from the midpoint of the incisal edge of the most prominent maxillary incisor to A-Pg line, expression of the protrusion of the upper incisors
22	Gl′-Sn-Pg′	°	Lower angle formed by the line from glabella to subnasale and the line from soft tissue pogonion to subnasale, expression of the convexity of the soft tissue profile
23	Cm-Sn-Ls	°	Nasolabial angle, expression of dentoalveolar protrusion
24	Li-E	mm	Distance from lower lip (labrale inferius) to Prn-Pg′ (Ricketts’ Esthetic line)
25	Ls-E	mm	Distance from upper lip (labrale superius) to Prn-Pg′ (Ricketts’ Esthetic line)
26	Li-S	mm	Distance from lower lip to Cm-Pg′ (Steiner’s line)
27	Ls-S	mm	Distance from upper lip to Cm-Pg′ (Steiner’s line)
28	OJ	mm	Distance between the incisal edges of the most prominent maxillary and mandibular incisors, measured parallel to the occlusal line