How does a dentist fix an indent in roof of mouth?

Two ways: One would be with surgery and the other with an appliance all the depends on location and size.

Ruggae or tori?: In the roof of the mouth toward the anterior there is sometimes a series of ridge formed by the mucosal folds, these are called ruggae. Ruggae is normal anatomical structure and no treatment is necessary. In the roof of the palate sometimes there is bony tubercle forming. The bony structure is termed palatal tori. The tori can be large and thus forming an indentation at the border.