The first factor to examine is the abundance and accessibility of mint oils. Mint oil is cheap and there is an abundance of it year round, which makes it ideal to use as a flavoring when mass producing products.
Another critical factor that keeps mint in favor as the top toothpaste flavor is the tingling fresh sensation that mint causes in the mouth. You have probably noticed that mint makes your mouth feel colder and leaves a sensation. This cooling feeling can be appealing or even addicting, and creates the assumption of fresher breath. This chemical reaction is what toothpaste manufacturers have been capitalizing for nearly one hundred years.