CT scans and models for implants?

[pt]

How many of you use these with your surgeons for implants for the ear,
nose or orbit? If they are cancer patients, they usually have a scan
already that could be used. If they haven't had a new scan in a long
time, do you get a more recent one? If they never had a scan, is it
protocol to order one. Do they ever order a temporal bone scan? If you
have a scan, how do you decide if there is insufficient bone? What is
the minimum amount of bone? Is there such a thing as too little bone
(bone grafts?)?

I'm asking this because I want to hear whether your surgeons think
they are necessary and what the protocol is in general. This has
nothing to do with your decision making or the quality of the
treatment you give, I'm just asking what are the preferences of your
surgeons you work with?

My personal opinion- We read all the time in journals that you should
get a scan for everything. I tend to think this stems from the dental
profession having x-rays in offices and they just become accustomed to
scanning. The locations of our implants don't significantly change and
we're quite limited to implant sites because we want the greatest
amount of compact bone. If we know where the sites are and know how
much bone is there anatomically (remember there is no resorption like
there is in the alveola), and no harm is done to the patient and no
bridges are burned- Why is it that we always are told we need a scan?
Is it habit or is it because we don't know cranial anatomy?

Paul