why would I need a bridge?

Usually because you have had a tooth extracted or knocked out in an accident, leaving you with a gap in your teeth. Closing the space is important for cosmetic reasons, but your dentist has good clinical reasons to fill in the space, too: leaving the gap open can put extra strain on the teeth either side. It can also affect your “bite” – the teeth on either side of the gap may lean together into the space and alter the way that the upper and lower teeth meet, which can cause further problems.