Weird teeth-cleaning trick that I discovered from suffering from interstitial cystitis / painful bladder syndrome (IC / BPS): toss a bit of baking soda in your water, such as 1 teaspoon per liter. It makes it alkaline. My teeth got whiter and felt better (less of a film feeling).
Baking soda is used as a cooking ingredient and shouldn't be too risky, but don't go overboard... bit of discussion on the IC / BPS aspect in the two citations below (including risks):
Baking soda is used as a cooking ingredient and shouldn't be too risky, but don't go overboard... bit of discussion on the IC / BPS aspect in the two citations below (including risks):
[Effects of urine alkalinization with sodium bicarbonate orally on lower urinary tract symptoms in female patients: a pilot study](https://link.springer.com/article/10.1007%2Fs00192-017-3492-...)
[Urine alkalization improves the problems of pain and sleep in hypersensitive bladder syndrome](https://www.ncbi.nlm.nih.gov/pubmed/24224617)
UPDATE: Also check edathamil toothpaste as I mentioned in a below comment https://news.ycombinator.com/item?id=27329165