Quote from healthcare.utah.edu, emphasis mine:
It seems like when you go down the toothpaste aisle now, you're starting to see more and more natural options and a lot of those have no fluoride in them. Are those toothpastes effective?
In terms of prevention of tooth decay, no. The only benefit that you'll gain is a fresher mouth with the natural toothpaste, but you will not receive any benefit against tooth decay if it doesn't have fluoride within it.
So the act of just cleaning your teeth at the end of the day, scrubbing them with a brush, that doesn't prevent tooth decay? You need to have fluoride?
You certainly need to brush your teeth. The question is, do you need toothpaste to clean your teeth?
You really do not need toothpaste to remove the dental plaque from your teeth. Purely the mechanical action of the toothbrush bristles and your dental floss disrupts the dental plaque that ultimately leads to tooth decay and gum disease. So you really don't need toothpaste. Now, toothpaste does have some benefits. Some will have some whitening agents for those who want whiter teeth with associated concerns, though, with abrasiveness, and sensitivity considerations. You would also have a fresher feeling mouth. But as far as removing the causative factors for tooth decay and gum disease, the toothpaste itself is not as important as purely the mechanical action of your toothbrush and your dental floss.
In other words, he says that non-fluoridated toothpaste is no more effective in tooth decay prevention than mere mechanical brushing. Is this statement true?