Question: What is the best nonprescription toothpaste with the most fluoride? I want the most potent toothpaste. I have no cavities, but I used to get cavities pretty quickly in the past. I want a strong toothpaste that will ensure I continue not getting any new cavities. What is the best toothpaste for that?

Reply: According to Fluoride toothpaste of different strengths for preventing tooth decay study, the specific strength of regular toothpaste is around 1000 to 1500 parts per million (ppm) fluoride, but many other strengths are available worldwide. 

No minimum fluoride concentration exists, but the maximum permissible fluoride concentration for toothpaste varies according to age and country. Higher concentrations are rarely available over the counter and are classed as prescription‐only medicine. Stronger fluoride toothpaste may offer more extensive protection against decay but also increases the risk of fluorosis (enamel defects) in developing teeth. 

I suggest discussing your concerns about cavities with your dentist to see what they may advise. Good at-home dental care habits such as brushing twice, flossing daily, and making and keeping regular dental checkups should help keep you cavity-free.