Before predictably successful dental implants were available to dentists, the only way to replace a tooth permanently was to attach it to an existing tooth, or multiple existing teeth. This is called a bridge.
Bridges are still very good ways to replace missing teeth, especially if those teeth already have large fillings or existing crowns. The procedure would simply be to crown the existing teeth and connect the replacement tooth or teeth to the crowns. This is then cemented to the existing teeth and functions as if the teeth were never missing. Missing teeth may be replaced in this manner for both function and esthetics.