The answer is short and simple: fluoride toothpaste.
There are many toothpaste manufacturers who claim that they have the best product. The only thing that determines the integrity of your toothpaste is essentially whether it contains fluoride or not.
There will probably always be a number of people prone to believe in conspiracy theories and do the opposite of what has been scientifically proven. The positive effect of fluoride, or natriumfluoride as it is declared on the ingredient list, is undeniable.
The discovery of the beneficial effect of natriumfluoride to countering cavities happened by accident in the United States in the 1930’s. After two water drillings, one found a significant difference in the amount of natriumfluoride present in the water. There proved to be a clear correlation between the amount of fluoride in the water and the number of cavities two identical groups of school children had.
There and then the effect of fluoride was discovered. And today, it is an integral part of all decent toothpastes.