The bottom half of my front teeth are darker than the rest of my teeth after using the daily whitening strips. Why? (photo)

This is one of the issues you see with whitening strips. They don't always align perfectly. Just as the lip sides of the teeth end up one shade and the tongue sides another. With custom whitening trays and gel it's usually not a problem. It will probably fade enough that it won't be that noticeable.

 

That is a common occurrence. It’s not that the bottom half is darker, it’s that the middle part is whiter. Once you stop whitening, your teeth shade will blend in more and you shouldn’t have that difference. Different areas of teeth soak up the whitening at different rates, That’s why you notice the effect. Give it some time and it will ok. I hope this helps!