Earlier quoted context omitted.
Although I haven't personally tried it, I have friends outside of the US that rave about Sensodyne Repair & Protect original with the "Powered by NovaMin" badging. NovaMin is composed of special ceramic particles that coat the teeth with a compound that reacts with the saliva to form a durable physical barrier. The problem is that the stuff with NovaMin is not typically available in the US. I just searched Amazon and…
As of a few years ago there's a similar FDA approved ingredient available in the US as BioMin. It works well for me and is cheaper than importing NovaMin.
Another option for leveling up on toothpaste is using those that contain micronized hydroxyapatite. Options here are Carifree or the Japanese brand Apagard available on eBay or Amazon. Biomin’s formula is proprietary but it might contain hydroxyapatite in part.
I stopped randomly getting cavities after using xylitol gum occasionally and brushing with these various toothpastes, n=1.
There also exist a variety of oral probiotics that claim to rebalance mouth flora away from species that cause cavities.
While no dentist ever told me about any of these options, at least Carifree is starting to market through US dentists.