Check out this lame excuse for an ad. Apparently, these people have yellow teeth.
Okay, either these people are also afflicted with serious jaundice (in which case, their teeth are the least of their worries) or these images were tinted yellow. I'm guessing the latter.
Learn how to use Photoshop, people. You could have focused on just the teeth, if you'd just read a little teensy bit of the instructions. They're under "Help".
Oh, and I'm pretty sure the second photo is supposed to be white. (The teeth, that is.) It doesn't look all that different from the first one.