Review (5/5): I'm glad I took the chance
I read through quite a lot of the negative reviews on this product, but decided to go ahead and try it. I'm glad I took the chance. My girlfriend had some serious stains that showed up on her teeth and we wanted something natural to gently remove them since she has extremely sensitive teeth. Sure it's a little messy and is best used at night to avoid any weird comments if the charcoal doesn't completely wash out. It's lightweight, so yes, it can very easily make a mess, but if you read the instructions and use a little common sense, you'll get over it pretty quick. The first use was a learning curve. We both decided to use it. I usually wet my brush and you can use this product on its own, or top off the toothpaste on your brush with this charcoal. If used by itself it does stain much more - your lips and teeth. It's best used before bed like this so you can brush out any residue in the morning. I recommend having a small nail brush handy. With this you can quickly rinse off the charcoal that sticks on your sink - it definitely won't stain the sink permanently.
This is great for surface stains and I've seen a slight color of change with my teeth - but nothing significant enough to say this is a great, strong whitener. If you have sensitive teeth, I recommend use only 2-3 times a week to check sensitivity.