I checked Wikipedia for the different types, and apparently I had a panoramic X-ray made last year.
A quick googling finds [1] which puts the maximum dose for X-rays at 0.17 mSv. Wikipedia [2] puts the average background radiation around the world at 3 mSv per year, or 0.082 mSv per day. So while 170 mSv is indeed "orders of magnitude more radiation" than an X-ray of a single tooth, it's still roughly in the order of magnitude I estimated (around a day's worth of background radiation).
Next time you go to the dentist, try to ask the person taking the x-rays what radiation setting they used or how much radiations you will be getting from the x-rays... in my experience, they don't know... Also ask them why they cover your torso with lead but not your brain...
Also, I think that you confused some units and you forgot to include link #2 ...
A quick googling finds [1] which puts the maximum dose for X-rays at 0.17 mSv. Wikipedia [2] puts the average background radiation around the world at 3 mSv per year, or 0.082 mSv per day. So while 170 mSv is indeed "orders of magnitude more radiation" than an X-ray of a single tooth, it's still roughly in the order of magnitude I estimated (around a day's worth of background radiation).
[1] http://www.ada.org/en/member-center/oral-health-topics/x-ray... (section "Radiation Exposure in Dentistry")