For a while now, there is known that lipsticks who have blue undertones actually make teeth look whiter.
Though sometimes it may be hard to determine what is this "blue undertone", because red with blue undertone - whiter teeth, red without blue undertone- unnattractive yelowish smile...
Drrrrums rrrolss please.... Enter - Clinique.
Using a dental color guide, Clinique compared the brightness of teeth before and after applying certain lipstick colors. These 10 were found to make teeth look a full shade whiter (believe it or not - it's optical illiusion)
Photo: Time Inc. Digital StudioClinique lipsticks in (from top) Peach Pop, A Different Grape, Cranberry Cream, Red-y To Wear, Raspberry Rush, Raspberry Glacé, Go Fig, Pink-a-boo, Ice Bloom, and Twilight Nude, $14 each; clinique.com.
So, you can grab the shade you like from Clinique, or just try to detect this shade on the other brand lipstics you like :)