False teeth could double as hearing aids

Jawbones transmit sound just as well as the bone that traditional hearing aids rely on

An X-ray image shows a person's jaw, including a tooth implant in the lower left jaw

A screw anchors a fake tooth to a person’s lower jaw in this X-ray image. Such dental implants can transmit sound well and could be used as part of a novel hearing aid design.

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Prosthetic teeth could make great hearing aids.

Vibrations applied to replacements for lost teeth travel well through jawbones to the inner ear, researchers report in the September Journal of the Acoustical Society of America. The finding could lead to discreet alternatives to conventional hearing aids and cochlear implants that people with hearing impairments often use (SN: 7/7/16).

Previous tooth-based hearing aids designs clipped onto molars and received sound wirelessly from a microphone placed behind the ear. Dental researcher Jianxiang Tao and colleagues want to take the concept a step further, turning tooth implants into hearing aids. The electronics that impart sound vibrations would be built into the portion of a false tooth anchored into the jawbone, says Tao, of Tongji University in Shanghai.

But first, the team had to determine how well dental implants transmit sound compared with natural teeth and the mastoid bone behind the ear, which other types of hearing aids rely on to work. So the researchers applied sound tones to the implants, natural teeth and mastoid bones of 38 people with hearing loss and a single dental implant. For a wide range of frequencies, the volunteers could hear sounds through implants as well as, or better than, through natural teeth or mastoid bones, the team reports.

Front-tooth implants appeared to work slightly better than dental implants toward the back of the jaw. That may be because jawbone at the front of the mouth is harder than jawbone at the back, the team speculates. Lower teeth and implants worked as well as uppers for transmitting sound. 

Compared with traditional hearing aids, dental implant hearing aids could offer “excellent concealment, good comfort and improved quality of sound,” the researchers write.

James Riordon is a freelance science writer and coauthor of the book Ghost Particle – In Search of the Elusive and Mysterious Neutrino.

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