To add further to your question, for a silver diamine dental product (Riva Star by SDI), the white precipitate disappears after applying more potassium iodide to the mixture. The excess solution in the tooth cavity is then rinsed off with water.
There is some cool chemistry going on here but I am unsure what it is.
Riva Star comes in 2 solutions that are mixed together in the tooth cavity.
Solution (1): Silver diamine fluoride has a pH of 10.
Solution (2): Potassium iodide has a pH of 7.
Tooth: Consists of collagen, proteins, hydroxyapatite, bacteria.
When solution (1) is first applied to the tooth, the high pH has been shown to aid in the formation of covalent bonds of phosphate groups onto proteins and crystallites to grow. It has been postulated that the fluoride usually reacts with hydroxyapatite, by replacing the calcium to form fluoroapatite, while the silver diamine exerts an antibacterial effect. The silver ions also react with the tooth structure to form the dark black silver phosphates.
So, the possible by-products could be Calcium ions, fluoride ions, ammonium ions, silver ions, silver phosphate.
The addition of solution (2) is to remove the excess silver ions that may form the dark silver phosphates. This is to avoid black stains on the tooth. Solution (2) is added into the cavity to form white precipitates and more solution is added until the white precipitate disappears.
What chemical reaction(s) could be going to explain the formation and dissolution of the white precipitate?