고민... Anyone aware of side effects of teeth whitening?

My teeth haven't been particularly white since I was young.

As I became an adult and started drinking coffee frequently, my teeth turned more yellow.

My teeth are too prominent when I smile, so I can't smile.

I looked in the mirror and smiled, but I was really surprised to see Hwangni.

I lose my confidence...

I'm really worried because whitening procedures involve scraping the surface of the teeth, which is said to be bad for the teeth.

Whitening toothpaste doesn't really work either...

What are the possible side effects of teeth whitening procedures?