everything is crap , none of it able to fight tooth decay, the best solution issalt, but the problem with salt is u cannot use it every day, and it burningsensition on the tounge, and dont swallow it, so its better to use 2 or 3 times in week, i heard from old village people, even i used it and found it worth, i dont know about other problems so consult your doctor before using it, but i think its safe because Colgate recently launched salt version.some people even use charcoal in our place.when using salt use with your finger rather than brush.the reason for this is salt kills bacteria. thats why they were used to preserve things in olden days.