Is there a tactful way to drop the hint that someone needs to whiten their teeth?

I have an acquaintance with badly stained teeth (coffee), and he would be so much more attractive without the brown teeth! He is single and a nice looking guy, and it would just be such an improvement on his appearance. I was thinking about telling him that I bought some new whitening strips, and I was going to use them just to try to open up the topic to discussion. I don't want to hurt his feelings because he is really nice! Please help!!!
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It's possible that this guy has sensitive teeth and can't use tooth whitening products (like me). Or, maybe he just doesn't care about the stains enough to do anything about it. Maybe one day you should say that your teeth are aching from these new whitening strips that you got... that way, you're still bringing the topic of tooth whitening up for discussion, but the conversation is still focused on you and it's not an obvious "hint." Hopefully you'll engage him and you'll find out why he hasn't done anything about his stained teeth. If he goes "oh" and lets the topic drop, forget about it-- he probably just doesn't care.
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