After all extractions, the gum and bone shrinks around where the tooth used to be. We think of this like the ‘use it or lose it’ principle with muscles - if the stimulus is no longer there, than the muscles will waste away.
This is why we ONLY perform a 2-bridge protocol. The initial bridge fits perfectly for the first 4-6 weeks but as the gum shrinks spaces can develop under the bridge as the gums shrink and heal. We wait three months before we rescan the tissue to fabricate a new final bridge as it is the only way to guarantee the final bridge will have no spaces where food can get stuck. This is because the under surface of the bridge is fitted with firm tissue pressure onto the gum underneath preventing food debris from getting stuck when you chew and eat.