When tooth decay spreads and attacks a tooth, it can usually be removed by a dentist and the tooth saved with a filling. However, if the decay is neglected or not discovered until after it spreads into the root canal of the tooth itself, then the nerve and blood vessels become infected from the bacteria which are part of the tooth decay process.
The bacteria easily and rapidly travel the entire root canal and of course they easily discover those tubules and their nutrient supply. The organisms have, in fact, found a new home, one in which they grow and rapidly reproduce.
Click here for Dr. Mercola's Video about root canals
HOW ROOT CANALS GENERATE TOXINS
Dr. Weston Price spent 35 years...in research. [For 14 years,] he was the...Director of Research for the Amercian Dental Association.... He studied diseases of the heart, kidney, uterus, nervous system and endocrine system resulting from toxins seeping out of root canal filled teeth. He became aware that a certain percentage of people are sensitive to toxins that are manufactured within these dead teeth. The treatments he researched are basically the same...that are [the] foundation of today's root canal work. Research convinced Dr. Price of many truths that we still have a hard time...[understanding], even today. We remain bogged down in "that's the way we've always done it" thinking. We have been too habitual to adopt this sense of new "truth". His extensive research covered 24 procedures.... In...[his]...[day], before extensive use of x-ray, the infection in the root canal went unnoticed or disguised itself as bone absorption. Local comfort of a treated tooth was...a sign of success.... Only...pus flowing from a tooth was...a sign of failure. However, Dr. Weston Price looked beyond the obvious.