With the Leafs about to embark on their bye week, the move gives the pair a chance to play with the Marlies.
Dermott has looked good in his limited action through two games, picking up his first NHL point (an assist) in a win over Vancouver.
A second-round pick in 2015, the 21-year-old has two goals and 17 points in 26 games with the Marlies this season.
Gauthier has played in five games for the NHL club this season and has failed to register a point.
The Leafs don’t play again until Jan. 18.