Hi Ajgund, Horsetail (Hymale particularly) has some good results helping to remineralize tooth cavity. It is recommended by holistic dentists, only use a week or two and take a break so you don’t have potential for stones to be created. And make sure it comes from a clean source as this plant will pull toxins from the soil. Doc Jones has monographs on Clove, Myrrh, and Calendula which are all useful for killing bacteria in the mouth so a good mouth wash could be made from a tincture of the first two plus a tea to swish around peacefully later in the day made with Calendula and a pinch of licorice. Also Oil Pulling using coconut oil helps to detox the mouth and has many beleivers in how much it helps overall health. All this said, it would be important to increase minerals and vitamins to the diet so her body has what it needs to strengthen her teeth and bones.  Good organic bone broth would be great plus the usual bone strengthening vitamins would probably be helpful. They say everyone is very low in Vitamin D these days, as well as, magnesium.  I hope you find this helpful. Blessings.