I got an easy solution for that. MIpaste. I had to use that after i got my braces off to get the marks away and it works! Its cheap and is amazing stuff! You should seriously look into it. (it's not a prescription nor do you need one) The only thing is use it ONCE a day and your not supposed to have anything to eat or drink after it but if you do then you just have to wait 30 minutes.
Rinse mouth with peroxide once a week.Then brush at least once a day with baking soda.Then go to just once a month with peroxide so not to ruin your enamel.Brush with a toothpaste with baking soda with the other 2-3 of brushing teeth per day.