Tooth phone provides covert chat:

A prototype radio device designed to fit inside a human tooth and provide covert mobile phone communications has been created by two UK students. The device currently consists of a digital radio receiver that converts radio signals into sound and a tiny vibrating component, which conveys sound to the wearer’s inner ear through bone vibrations. New Scientist

Psychiatric reactions: this will not sit well with a number of paranoid schizophrenic patients. For decades, it has been a fairly common delusion, on the transmitter side, that their dental fillings are bugs. On the receiver side, some explain the auditory hallucinations that are a prominent part of the illness by invoking the small receivers that have been implanted in their heads, and sometimes their teeth. And I have heard tales of people being able to hear actual radio broadcasts, supposedly because their dental fillings are resonating with the broadcast frequency. This Google search on ‘ “dental fillings” and “radio” ‘ will take you further, you hear?