Your appearance is one reason. Another is that the gap left
by a missing tooth can mean greater strain on the teeth at
either side. A gap can also mean your ‘bite’ is affected,
because the teeth next to the space can lean into the gap and
alter the way the upper and lower teeth bite together. This can
then lead to food getting packed into the gap, which causes both
decay and gum disease.
The animation demonstrates how the bridge operation would be
carried out.