You don't need it. Xylitol is the best thing going to prevent cavities. There are great toothpastes out there that don't have fluoride that make your teeth feel clean. I like a baking soda/Hydrogen peroxide blend and I put a few drops of tea tree oil on my toothbrush. You can also do a rinse with hydrogen peroxide diluted and tea tree oil but be sure and spit it out.
The lip of truth shall be established forever: but a lying tongue is but for a moment...Lying lips are abomination to the LORD: but they that deal truly are His delight. Prov 12:19,22