Irving, who most often plays at strong-side linebacker in the Broncos' defense when Von Miller is moved to defensive end in some of the team's personnel groupings, injured his right shoulder on a touchdown run by the Chargers' Ryan Mathews Sunday. Irving did not participate Wednesday, but interim head coach Jack Del Rio has said he's hopeful Irving can return to practice on at least a limited basis at some point this week.
Dreessen had been limited last week as well -- he had two arthroscopic procedures on his knee before the regular season started -- but is expected to practice this week.
Cornerback Champ Bailey (left foot), who has played in just two games this season, also returned to practice for the first time since leaving the Broncos' Oct. 20 loss to the Colts. Bailey took part on a limited basis.
"Great to have Champ back ... we'll see how the week goes," Del Rio said.