I recall that it had been written in the 1950s. My memory could be wrong. I read it some time in the early 1980s. Having aged a few decades since, and experiencing much comedy and fiction in that time, I have come to discover this must have been a common theme from whatever era it was written.
The details I recall from the story are: 1) boy gets a tooth filled with a new alloy. 2) Soon discovers he can tune into different radio stations but adjusting his jaw. 3) Proves this to his friends by telling them what's on which stations, which they verify by tuning the radio. 4) Looses the ability quickly (days, perhaps?) - can't recall if by re-visiting the dentist or some other reason.
I don't recall that the plot of Fat Men From Outer Space (remove all junk food) was involved - seems like it'd be a fairly large plot to miss, but I admit the human brain is a strange thing.
I believe Lucille Ball claimed she helped zero in on a Japanese spy during WW2 as her root filled teeth chattered with the morse code sent by the nearby clandestine transmitter.