Brushing teeth with soap
On possible benefits over toothpaste, tooth powders etc.
To my awareness, Dr. Gerald Judd, PhD (author of Good Teeth, Birth to Death), was the first to recommend using bar soap (not liquid soap) to clean teeth and gums properly. His rationale among other things was that most toothpastes contain glycerine which according to his research forms a coating on the teeth requiring 20 rinses to remove. A coated tooth cannot absorb calcium and phosphate minerals from food to remineralize itself. According to Judd, brushing with soap washes oils off the teeth and disinfects the gums, with the bacteria being killed by the soap.
While reportedly people use various kinds of bar soaps for toothbrushing with "everyone noticing improvement", personally I recommend using a natural unscented soap (or with essential oils only) but (for safety and if available) without glycerin ("beware" however of handmade soaps since in contrast to industrial soap, the glycerin is not removed). Conventional store-bought soaps contain numerous man-made chemicals (additives, artificial fragrance/perfume etc.). It may be best to look for "cold process" soap made with only pure natural ingredients.
Someone commented that "Dr. Bronner's is a good choice because it's mild enough to use for brushing my teeth".
Some testimonials for brushing teeth with soap
Severe gum disease of 20 years standing cured
See Brushing with simple bar soap "miraculously" cures severe chronic periodontal disease with loss of teeth - conventional toothpaste and rinses failed.
Cleaner teeth and fresher breath
We've already started brushing with one drop of olive oil shampoo (see Edgar Cayce) with very very positive results in a short time. It's not at all unpleasant and leaves the teeth and gums feeling much cleaner, fresher and better than even the best health toothpastes which all seem to have glycerine in them. We've found that the 'itching' that always seemed to characterize the teeth and gums is gone and the teeth actually feel much cleaner for much longer as well as our breath being fresher."