Dunn will be out indefinitely and will not travel with the Bulls to Atlanta for their Saturday game.
The Bulls initially said he chipped and dislocated two front teeth but was clear of concussion symptoms after initial tests.
Dunn's two dislocated front teeth were stabilized and have been splinted with braces as a form of treatment.
Dunn, 23, acquired from Minnesota during a summer trade, is in his second NBA season. The former lottery pick is averaging career highs in points (13.7 per game), assists (6.4), rebounds (4.6) and steals (2.1).