1 tablespoon Bentonite Clay
1 tablespoon Diatomaceous earth
0.5 teaspoon Borax
0.25 teaspoon Himalayan salt
Approx 8 drops of essential oil (I use peppermint or eucalyptus).
Edit 19/09/2021: The essential oil could be substituted for ground cloves, perhaps 1/8th of a teaspoon. Credit to 
@atma.love/healing-toothache-holistically
Put first four ingredients (dry) in a small glass jar and shake well to mix. Then add essential oil and shake well again.
Slightly dampen toothbrush and dip into powder.
Tastes and cleans very well and ingredients have healing properties unlike commercial toothpaste which are detrimental to health.
Toothbrush made of bamboo and has charcoal impregnated bristles. It's good to spray with MmS solution to disinfect before dipping. The works as the damping method to help powder stick to brush plus MMS is also good for mouth health.
Namaste
Atma