Reply To: Cranial Base Flexure

[Chad Carter (Course Director)]

Samantha,

First, trust looking at the ceph and your initial impression. Taking time to do a cranial base calculation may not always be worth the squeeze – for example you can easily identify they are Class II or Class III.

Do you have a sample ceph of what you are seeing? I’d like to look at it to make sure I can help clarify my thoughts.

Now we are all clear on how cranial base is calculated.

The three planes SN (the cranial base), Franfort Horizontal, and Mandibular plane contribute to make the three angles. So if FMA is giving you a “normal” number and SN-MP is “off” then that’s a clue for a cranial base calculation. Likewise if SN-MP is “off” but FMA is “normal” that would also be a clue to check the cranial base. So if either SN-MP or FMA are out of norms that helps us identify a steep or shallow cranial base. If its just a degree or two off then I don’t find it’s worth my time doing calculations but if it’s a cranial base of 15 degrees then the calculations could “help” me identify which jaw is at fault but I’ll also still be trusting my eye’s initial impression.