scottma, Thank you VERY much
for your comment. Please, please tell me research references (published in journals?)
for your information. A car accident long ago smacked the right side of my head. Root canal infections started later. In spite of intense pain, dentists (high level) in Japan insisted there was no problem because nothing showed on x-rays. Then, several times, the various infections burst into my mouth or nasal passages. The nasal infection was undetected for years.