People need to understand how teeth bleaching works. People always ask if “teeth whitening actually works”, or if at home teeth whitening actually works. If the product has hydrogen peroxide or carbamide peroxide in it, it’ll work. Professional ones just have more peroxide then at home ones so they work faster. You don’t even need a kit, you can just brush your teeth with peroxide. They are guaranteed to work, just like water is guaranteed to make something wet. Peroxide bleaches teeth, it will never not bleach teeth. The only exception is if you teeth are yellow because they’re covered in plaque instead of stained. In which case the plaque would need to get removed first.