I think I realized why!

[Azash]

I'm not sure how many people know, but my teeth are kinda yellow...

Well, it didn't really start until after I noticed my toothbrush was in really bad shape, and I stopped using it. This was in January.

Sure, if I didn't have to use money for other stuff, it would've been no problem, but I only got a new one yesterday.

I think it didn't mess up my immune system, as I've been as healthy as usual since then.

 

[thetrooper]

This sounds vaguely familiar...

 

[Atlas14]

Your teeth could also be yellow from whatever you are eating/drinking too much of, i.e. the sugar.

 

[Xanikk999]

Having yellow teeth isnt particularly bad, its unnoticable as long as you smile without showing your teeth. Just dont get cavities like i do!

 

[thetrooper]

He's just messing with you guys:

http://forums.civfanatics.com/showthread.php?t=216478