Session sustained a concussion in the preseason and in Sunday's loss at Cleveland. He also dealt with hand and elbow injuries during the season.
Bentley is in his 10th season and has spent time with Cleveland, Seattle, Houston and San Diego. Bentley, a fourth-round draft pick in 2002, has 233 tackles, four fumble recoveries, two sacks and an interception in 132 career games.
Bentley spent the past three seasons in Houston. He was with San Diego in the preseason before being released in final cuts.