You might think that the only reason you would need braces is because you have crooked teeth, but that's not always true. Malocclusion (ma-loh-clue-shun), which means "bad bite" in Latin, comes in many forms. Teeth become crooked when a person's jaw is too small, but sometimes a person will need braces even if their teeth are straight. The top or bottom jaw bone can often be bigger than the other, which will cause either an overbite (when your top jaw bone is bigger) or an underbite (when your bottom jaw is bigger). Braces are also used to help these conditions.