If a growing portion of the dentistry industry was discovered to have been weakening people's teeth at the government's request, I'd start to buy Bob a beer a little more often.
It turns out Bob was actually receiving radio transmissions from the ADA through his fillings. He's a sleeper in the underground dentist community, waiting for the call to turn his xray machine on when the TSA releases its ruling on the need for back-scatter surveillance to prevent the next tooth-bomber from hijacking civilian aircraft. Be careful what you say around Bob.