Amazing to think that the gnathograph, which looks about as comfortable as Clockwork Orange's crazy eye-opener device but for your teeth, was ever considered a good idea. But there it is, in the June, 1939 ish of Popular Science.
WITH the aid of the "gnathograph," an instrument as mouth-filling as its name, a dentist's patients may now be assured of a perfect fit for artificial teeth. Fitted to the jaws as shown above, the new device registers the arrangement of the teeth and the direction of the "bite," to guide the dentist in straightening teeth or fitting inlays, crowns, bridges, and plates. Its inventor, Dr. Beverly B. McCollum of Los Angeles, Calif., demonstrates in the picture at the right how the instrument is then mounted for use in tooling a plate to just the right shape to give the most comfortable fit in the mouth.Link