Pollard and Sibert combined to score 12 points during Dayton's 14-2 run for a 57-39 lead with 2:29 left.
Dayton (15-2, 5-0 Atlantic 10) has now won 15 of its last 16 regular season conference games dating back to last season.
Dyshawn Pierre added 10 points, 12 rebound and five assists for the Flyers. Pollard, a sophomore, was 8 of 10 from the field but just 4 of 11 from the free throw line.
Saint Louis made just three field goals in the final 10 minutes - two in the final 1:30.