SNA, SNB and ANB

[ha1999]

Anyone can please explain what can the SNA and SNB angles say about the direction the jaws moved in (forward/backwards) in table 1 and table 2.

Also how come the ANB is different for the same patient pre-op?

Any help would be much appreciated.

	Pre-op	Planned 3D
SNA	83	82.9
SNB	83.8	83.5
ANB	1.3	1.4

Table - 1

	Pre-op	Planned 3D	Post-op
SNA	82.5	82.6	82.8
SNB	84	83.7	84.8
ANB	1.9	1.7	2.6

Table -2