Bergeron headed down the tunnel early in the third period after a deflected slap shot from David Pastrnak missed his visor and hit him in the face.
The Bruins captain was in apparent pain, having medical attention, but would emerge back on the bench later in the period, helping his side round out a third straight win.
Despite returning to the ice, Montgomery revealed Bergeron had not been cleared by medical staff yet.
"How much respect I have for him coming back after, I know the puck got deflected, but it hits him up high and in the face," Montgomery told NESN.
"The admiration I have and everybody has for him coming back to try to help the team win after that is immense.
"We're hoping that all the X-rays come back good."
"I couldn't be more happy, it's been overwhelming," Ullmark said. "I have a lot of gratitude playing with the boys who work so hard every night."
The Bruins are the NHL's only 30-win team, improving their record to 35-5-4.