How come adults teeth are smooth and nice on the bottom and kids teeth are all bumpy?

Question

How come adults teeth are smooth and nice on the bottom and kids teeth are all bumpy?

Answer 1

Those little bumps are distintive to younger teeth and are called mamelons....

As we age they wear down, and are just another sign of being younger....

Answer 2

Because the bumps have worn off by the time we are adults

Answer 3

because they're teeth havent worn down yet from being bumby, so they can push through the gums