To clean the teeth, what is most important is a mechanical cleaning. On Ibiza traditionally the leaves of the white rockrose are used to rub the teeth.
After a contact with an acid (for example lemon juice) it's best to wait at least half an hour until rub the teeth.
A toothpaste easy to make, although the ingredients need to be bought, is the following: We take coconut fat and baking soda (sodium bicarbonate, NaHCO3, not to be confused with baking powder) in equal parts, mix them (heating the oil a bit), and that's it. If you want, you can add essential oils for the taste. If it is essential oil of sage, it is also good for the gums. Other ingredients like aloe are possible.
After using the tothpaste we can rinse the mouth with sea water.