The ostomy story is disturbing and points to TSA people who are not well trained. From looking at the TSA website, they have included people with disabilities in their planning for various screening. I know that the TSA agents we have encountered in Minneapolis and Orlando when traveling with DD in her wheelchair have been generally very nice and very professional. But, with as many airports and as many TSA staff as there are, it's not a surprise that some are rude or ill trained.
Interestingly, on the question of braces, I found a TSA page I had not seen before.
The first page talks about passengers with braces, artificial limbs, etc (and does include your rights - like they will not require you to remove the braces - so you probably want to print it out).
It also includes some information about ostomies that says passengers should advise TSA agents that they have an ostomy and that they will not be required to remove it. There is some information on that page about external devices (which would include ostomy appliances) which is contradictory:
"If you are wearing an exterior medical device and are uncomfortable with going through the metal detector or be handwanded, you may request a pat-down inspection and visual inspection of your device instead.....
# Security Officers should not be asking you to remove your orthopedic shoes, appliances, or medical device (insulin pump, feeding tube, ostomy or urine bag, or exterior component of cochlear implant) at any time during the screening process.
Advise the Security Officer if you have an ostomy or urine bag. You will not be required to expose these devices for inspection."
That page is not new, but there is a link on that page to
a page about a new technology, introduced in 2008 called CastScope, which allows TSA to check casts, braces and similar devices without having them removed. From the description, it is the same general technology as the new AIT scanners, using back scatter technology to produce a clear image of casts, prosthesis, etc.
This is a page about AIT scanners from the TSA website that talks about how they work. From what I have read, some airports have had backscatter technology AIT scanners installed - which sound like they would be able to handle casts, braces and other devices. Some airports have had millimeter wave technology scanners installed, which I can't find out anything more about whether those will clear things like casts, braces, etc.