Normal mouth bacteria don't make lactic acid from Xylitol.Xylitol is a 5-carbon sugar. 6-carbon sugars can be made into lactic acid by bacteria in the mouth. These bacteria are always present in the environment and will repopulate the mouth from the air and the environment. These bacteria are in animals' mouths though animals don't usually eat 6-carbon sugars so they don't have tooth erosion from lactic acid.The bacteria make an acid (lactic acid) that eats the teeth. This only happens when these special bacteria eat 6-carbon sugars. This toothpaste contains Xylitol (a five-carbon sugar) and is so much better than flouride toothpaste. Flouride contains flourine which is the most reactive element in the universe (electronegativity of 3.98 on the Pauling scale). Basically, flourine (like chlorine in bleach) will react with the outer layer (cell membrane of bacteria) and kill them. The bacteria leak out their guts where the flourine reacts with the cell membrane. The flourine also reacts with organic molecules called enzymes which can stop the lactic-acid producing bacteria from destroying teeth. The flourine will stop the bacteria from making lactic acid, however, the flourine also reacts with the brain and it helps bring positively-charged aluminum into the brain where it definitely doesn't belong. Aluminum is in the salt of most fast food restaurant. Read a packet of salt at a fast-food restaurant next time you go to one.Though flourine is not a major cause of hypo-thyroidism (low-thyroidism), flourine can replace iodine and deplete the thyroid gland. There are other industrial pollutants (like perchlorate) that replace the iodine and result in hypothyroidism more easily. Teeth re-mineralize from the saliva which contains calcium and phosphorous. Flourine is not the correct material to rebuild the teeth.The above statements are my opinion. Figure out the facts for yourself before trying anything. I am not responsible to big pharma or anyone for any statements made, etc. etc. etc. I do feel the above statements are true and we have been lied to about flouride so it can be sold to water companies as a good chemical when it is really harmful. Thank you.