Originally Posted by Anthony
As someone who has been in similar circumstances, I understand your concern about discussing the subject gently. If his top teeth are false, what would you have him change about them? Unless they aren't being cleaned, I can't see how there would be a problem.
When you decide to speak with him about it, you might want to consider bringing up the topic and directing it towards yourself instead of at him. One way of doing that would be to ask him for his opinion on something dental-related, of which he likely has experience if he has false teeth. For example, "I've been thinking about trying a package of Crest Whitening Strips to see if they're actually effective, do you know anyone who has used them?"
From there you may be able to start a small discussion on the subject, which should present you with the opportunity to ask him about his teeth with the least amount of discomfort.