Dental bridge are for people who wants to fill up the gap of their missing tooth, Basically a dental bridge are two crowns on each side of the gap, these will now hold or anchor the false tooth that will be placed in the middle of the two crowns.
Why have them? they can fill the gap of your teeth making you retain the shape of your face, prevents your teeth from drifting away from each other and many the like.
Does it cost much? well it depends on your dentist, so if you want to have your smile back call your dentist to ask if how much will it cost and of course if it is possible for you to have one.
How long would a Dental Bridge would last? roughly 5-8 years depending on your oral hygiene, so always take care of those tooth to avoid losing them in the first place.