An open bite is a situation where the teeth do not meet during a biting action. That means there will be a space between both rows of teeth while trying to eat. Obviously, this will result in more than an aesthetic issue, but one of a functional problem to be resolved.
There are a number of reasons an open bite can occur, but usually it is traced to a genetic issue, malfunction of the tongue, mouth breathing, thumb sucking, or a combination of the above. There are also a few conditions of the jaw that will develop into an open bite.