There are two things everyone should be aware of
1) Dentists see a spot on the their x-ray they call a pre-cavity, and then drill. Often this is a false positive, and you never really had a cavity to begin with, so you can easily cure yourself of their false positives.
2) Saliva does a lot to help your teeth. But every time you eat you are making it harder for it to do its job of protecting your mouth. Intermittent fasting, or people who only eat once or twice a day, have a much easier time maintaining dental health.
There is no amount of brushing that can help you if you are constantly snacking all day. If you do a Keto Diet (very low sugar) and don't eat anything at all for 16+ hours a day, a lot of people will find that their cavities shrink and disappear over time as your body creates new enamel faster than you are destroying it.