How will having braces make my adult tooth come down?

I'm 14 and last week I had my final baby tooth taken out at the dentist. It's the third one along to my front teeth, not sure of the proper name but often people call them 'fang' teeth. Now the dentist has sent me to an orthodontist to get molds to have braces but the rest of my teeth are perfect, I just have this gap which is making me look like some sort of pirate. I know I'm not an expert but I don't understand how braces will help it to come down. When I was younger they just came down themselves. Does anyone know how long it will take for it to come down if I did have braces? Thank you for the help! :)