The gist of the research and of the thousands of animal studies is this: That root-canal-filled teeth always remain infected no matter how good they might look or how good they might feel.
Dr. Price suspected that bacterial infection accompanied many degenerative illnesses. In the beginning, he didn't know what bacteria were involved or just how they contributed to so many disease conditions. But he did recall that in medical practice doctors made cultures from the infection site, grew the organism present in a culture medium and then injected the bacteria into an animal to see if they could reproduce the disease and thereby prove it was the cause of the illness.
Dr. Price suspected that these infections arose from the teeth. He decided to implant an extracted root-filled tooth under the skin of an animal. He felt that if bacteria were present and carrying illness, their presence in a tooth might offer the same kind of proof physicians found when they injected the bacterial culture to produce disease in an animal. That is exactly what took place. He found that by implanting the root-filled tooth, the disease of the patient was transferred to animals. Whatever disease the patient had, the animal with the extracted tooth under its skin developed the same disease as the patient.
In other words, if the patient had heart disease, the animal developed heart disease. If he had kidney trouble, disease of the kidney was transferred to the animal. If he had a problem in his joints, the animals' joints became similarly involved. The principle held true for the whole spectrum of human ailments. Whatever the disease, the animal would develop that of the patient.