Is it normal to stare at a persons teeth while they're talking?

This is why I don't masticate in front of strangers.

What do you do with people who have no teeth?

I don't like white teeth. I know someone who has bizarrely white teeth with blinding capabilities. There are been times where I have found myself fixated on staring at this person's teeth! When this happens, I try to look elsewhere. I tend to look a lot into this person's eyes. You can try this but be warned, some say that if you look into a person's eyes for a period of time, that the person will think that you are attracted to them.

This is a bit weird. You should be looking them in the eye.

It's better than staring at their chest or genital areas.

this is why i will bite you to died
you are abnormal

I think this is very normal, especially when there is something odd about their teeth. Outdoors, I always wear shades, so few ever have any idea what I am focused on. Inside I sometimes forget people can see my eyes and that can become a little embarrassing..
I think they call it wandering eye syndrome, and it happens whenever a pretty girl is near; bad boy, get a grip, no, no, not that.....whoops

Since you're aware of this, just make a concerted effort to look at their eyes whilst speaking.

I used to find I would avoid eye contact during conversation (it made me feel uncomfortable), but eye contact is important, so I made an effort to remedy the problem. Rather than look at their eyes, I looked between the eyes - people can't actually tell you're looking at the top of their nose rather than their eyes. Eventually I got over the habit of looking away.

Why not try something similar. Force yourself to look at the speaker's eyes instead of teeth. Eventually it'll become habit.