I could be wrong on the intent here, but in English we would say 'There's something in your teeth.' We use this when a piece of food is caught in between teeth (like a piece of lettuce or broccoli or something). I think this what the Indonesian sentence saying, but I could be wrong. Best example I can think of is in the cartoon The Emperor's New Groove and yzma has a piece of broccoli in her teeth. Kuzco could have told yzma 'there's something in your teeth'. Saying it as 'on' just sounds weird.
Agreed that "in your teeth" is more common, but "on your teeth" is grammatically fine, and might be used in certain circumstances. For example, if someone had lipstick on their teeth.