The men were part of a Facebook group called the Class of DDS 2015 Gentlemen. The group was removed from Facebook late last week.
CBC News has obtained screenshots of the group's posts, which are sexually explicit and appear to involve discussions of female classmates.
In one post, members were polled and asked, "Who would you hate f--k?" They were given two names to vote on.
Another post shows a woman wearing a bikini. The caption says, "Bang until stress is relieved or unconscious (girl)."
The screenshots also include conversations among the members in the past few days. From those images, it is clear that members of the group were concerned there had been a leak and that the school's administration was now involved.
Jokes about chloroform
"RED ALERT!!!!! RED F--KING ALERT!!!!!" reads one post. "Apparently one of the ladies has seen or heard something about the recent posts in the gentleman's. We have to get rid of the evidence."
The group then launched another poll asking its members whether it should "Do nothing," "Hold off unless the shit hits the fan," "Put posts on the DDS Class of 2015," or "Issue statement of some sort."
Their conversations also include jokes about using chloroform on women.
The words: "Does this rag smell like chloroform to you??" were superimposed on one photo.
In response to another photo of a bikini-clad woman, two members wrote: "Can you tell me what this chloroform smells like?" and "Does this mask smell like nitrous oxide to you?"
The group had at least 12 members.
CBC News has decided not to name the men involved at this stage of the investigation.
'We're taking it very seriously'
Janet Bryson, a spokeswoman for Dalhousie University, told CBC News late Monday afternoon the university is aware of the group.
"We are aware that there were some inappropriate comments online. We're taking it very seriously. And we're taking the steps that are available to us to look into it," she said.
"It's a bit of a complicated process. There might be a number of students that are involved and trying to ensure that they're getting the support that they need as we go forward investigating it."
At least three of the men have removed their Facebook profiles in the past 24 hours.
The Dalhousie University investigation comes one year after Saint Mary's University launched a probe of its own into sexual impropriety. That probe began after first-year students were seen in an online video reciting a pro-rape chant.
CBC News spoke with one dentistry student on campus on Monday who said he was "aware" of the group, but wasn't a member. He thought it was a group formed for people who wanted to "gripe."
When reached by email Monday, one of the group's members directed CBC News to his lawyer.