In the original concept chlora percha was used as a filling material.
The problem is that as the chloroform dispersed (or evaporated) the filling became smaller, by as much as 20 percent .
This of course, left a gap between the filling material and the wall of the canal.
Along the way someone figured out that if the chloroform was used to temporarily soften the outside of the gp cone, then the gp could be adapted to a canal wall and after fitting could be coated with cement and inserted into a canal.
Since chloroform has been identified as a carcinogen it's use has pretty much been abandoned.
Even if the chloroform is completely evaporated from the GP and thus is safe for the patient, the fumes are an environmental hazard in the office.