Basically, I used to be not much of a smiler because I'm not a great fan of my open-smile; I expose a lot of upper gum (inherited from my dad). I have no problem with smiling sincerely, but I'm a little self-conscious about when I use teeth because I flat-out don't think I look attractive at all, more crazy than anything. I'm sure I could "learn" to not expose the gum, but then I can't smile sincerely with my eyes because I can't even use those muscles.

Is there any hard evidence to suggest teeth are a bonus in some fashion?