Obi Toppin scored 18 points. Ibi Watson had 12. Ryan Mikesell and Trey Landers each added 10 points. Rodney Chatman scored eight.
Dayton shot 64.8 percent from the field and 40 percent (10 of 25) from 3-point range. Dayton had 25 assists to St. Bonaventure’s seven.
The Bonnies (12-7, 4-2) suffered their second straight lopsided loss. They lost 91-63 at Virginia Commonwealth on Saturday.
Anthony Grant: Postgame press conference after win against St. Bonaventure
Dayton outscored St. Bonaventure 17-3 in the last four minutes, 16 seconds of the first half to build a 47-29 halftime lead.
Dayton put an exclamation point on the half with four points in the final four seconds. Crutcher scored on a layup and then missed a free throw. Dayton got the rebound, and Toppin hit a jump shot at the buzzer.
Crutcher led the Flyers with 13 points in the first half. Toppin scored 10 points and dunked three times. Mikesell had eight. Chatman had four of his six points in the first two minutes. Watson and Landers each scored five.
Dayton shot 69.2 percent (18 of 26) from the field and 45.5 percent (5 of 11) from 3-point range. The Bonnies shot 40 percent (12 of 30) from the field and 11.1 percent (1 of 9) from 3-point range.
St. Bonaventure played without its best big man: sophomore forward Osun Osunniyi, who missed his second straight game with concussion-like symptoms. He did not travel with the team to Dayton. He averages 9.9 points and 9.3 rebounds per game.
• ARCHDEACON: No moment too big for Crutcher
• THE BUZZER BEATER: All the angles on Crutcher's shot
• ST. BONAVENTURE PREVIEW: Flyers seek eighth straight win | Game preview
• POLL POSITION: Flyers not letting ranking go to their heads
» NATIONAL ATTENTION: Dayton 'most fun team to watch' in college basketball
» SAINT LOUIS GAME: Crutcher's mom was too nervous to watch | Grant proud of team's character and resolve | Photos of the big shots and the celebration | Photos of the first 40 minutes