Six of them if the article is accurate. It's from the Encyclopaedia Britannica Book of the Year 1966...
I also found this short article about it:
https://archive.macleans.ca/article/1965/9/18/broadcasting-your-biteI'm not sure I'd volunteer for this type of nuttiness, couldn't they just glue sensors to a normal tooth and have wires to the outside??
And how the heck did they recharge those batteries? Did the volunteer have to stick his head into a 1965 Amana Radarange?
I wonder if this really happened or it was just someone's plan at the time, I can't find any corroborating info. If the idea was to have the tooth broadcasting continuously you'd need to be near a receiver and a chart recorder when chewing I suppose. There weren't any IBM 360s that could fit in a tooth in 1965. Right?
Anyone ever hear of this??