The 22-year-old was injured on a hit from behind by Oilers forward Brad Malone in the third period. Before departing the ice, Dermott was in visible pain and appeared to be holding onto his left arm.
After the game, head coach Mike Babcock announced Dermott was week-to-week with a shoulder injury. Babcock added that the team will recall defenceman Martin Marincin from the AHL and pair him with Justin Holl, who has been a healthy scratch for all but two games this season, in the Maple Leafs’ game against the New York Islanders on Thursday.
Earlier in the day, the Maple Leafs announced Gardiner was also out week-to-week with a back injury.
In 59 games this season, Dermott has recorded four goals and 13 assists. The Maple Leafs won the game 6-2.