Measurement

Normal value

Patient reading

Interpretation

SNA

82 degrees

79 degrees

Retrognathic maxilla

SNB

80 degrees

77.5 degrees

Retrognathic mandible

ANB

0-4 degrees

1.5 degrees

Class I skeletal base

U1-Maxillary plane

108 +/− 5 degrees

100 degrees

Retroclined upper incisors

U1-(S-N) Plane

103 +/− 5 degrees

89 degrees

Retroclined upper incisors

L1-Mandibular plane

90 degrees

80 degrees

Retroclined lower incisors

Mandibular plane angle ((S-N)-(Go-Gn))

32 degrees

41 degrees

High angle

Frankfort mandibular plane angle

25 degrees

35 degrees

High angle