Pulled teeth and tooth decay, especially of the upper jaw
In the first half of the 20th century, most of the causes of mental illness were not understood, and aside from post-mortem examination, even decomposition and lesions of the brain could not be outwardly diagnosed. Today, we may not know all of the causes, but we have a much better idea than before - but that didn’t stop people from speculating before we had the technology to know for sure.
Henry Cotton, who managed the New Jersey State Hospital at Trenton, believed that tooth decay and bacterial factors were the primary cause of mental illness. Because of this, he promoted such procedures as total tooth removal (if all teeth showed even mild decay - the norm for most people in those days), which, unfortunately, led to multiple documented deaths due to post-procedure peritonitis and sepsis.
While it was (and is) inadvisable to keep your teeth and gums in a state of ill health, there’s no link between mental illness and oral bacteria, and you should probably not remove all of your teeth in pursuit of a clear brain. In fact, I’d go as far as to say you may want to contact your local psychiatric hospital if you have any urges to do as much.
The Defective, Delinquent, and Insane. Henry Cotton, 1921.
