Regehr had missed seven games with a lower body injury from a 3-2 loss at Washington on Jan. 27. To make room on the roster, the Sabres (5-6-1) waived fourth-line forward Matt Ellis for reassignment to Rochester in the AHL.
Struggling defenseman Tyler Myers was a healthy scratch for a second consecutive game. Rookie center Mikhail Grigorenko was a healthy scratch for the first time this season.
For the Bruins (7-1-1), center Shawn Thornton returned after missing two games with a concussion. Also back were forwards Daniel Paille (upper body), who missed two games, and Brad Marchand (upper body), who missed one game.