The dose equivalent for neutrons is at most 20 times the dose of xrays, and that’s for the worst-case around 1 MeV.
The cookie test does not mention the intensity of the individual emitters. I’d prefer to hold a small neutron source from a moisture gauge over merely being in close vicinity of an iridium-192 radiography pellet. Those things are bright.
Besides, if a limited dose of neutrons into a hard tissue of the tooth significantly lowers the risk of a toothache, I’d consider it a win.
And the permitted doses are ridiculously low anyway. The linear no-threshold model is not supported by observations, and the longer-term effects of even fairly high single doses are less catastrophic than the public mythology of radiation effects would suggest. Check e.g. the list of criticality accidents, and the fates of the survivors, for some extreme doses that involve even the bad’n’ugly neutrons.
