Bests & Worsts Reviews from Amazon

I saw this advertised via clickbait link on a different website...I figured it's only $25, and decided I'd give it a shot. I used it once a day for about two weeks, and the only thing it did was irritate my gums. My teeth are absolutely no different. I spoke with my dentist about this at a regular cleaning appointment, and he had concerns of the abrasive nature of the product, and told me there is absolutely zero research showing that activated charcoal has any whitening effect on teeth, and that if there is a whitening effect, it probably is because the abrasive powder is rubbing off the top layer of enamel (which would explain why there are quite a few people saying it made their teeth more sensitive). He recommended I stop using, and I have. I'm extremely suspicious of a lot of the positive reviews...especially the "My teeth are whiter after 1 use" reviews. I think there's something fishy going on.