Irving added five pounds of muscle during the offseason so he would be able to handle any contact on drives to the basket. But he wound up losing the weight after he had four wisdom teeth pulled.
Irving's injury isn't the only one impacting the Cavs.
Second-year forward Tristan Thompson sustained a nasal fracture in Sunday's loss to the Sixers. He will be fitted with a protective mask and is projected to be available for Wednesday's home game against Philadelphia.
Also, guard Daniel Gibson has a bruised right elbow.
The Cavs just got back rookie center Tyler Zeller from a concussion and broken cheekbone. Zeller was elbowed in the face during a recent game in Los Angeles and is playing with a protective mask. He scored six points against the Sixers.
With Irving out, coach Byron Scott, who gave his road-weary team the day off Monday, will have to juggle his starting lineup and rotation. He could move rookie Dion Waiters from shooting guard to the point.
Scott has been disappointed with his team's defense so far this season, but without Irving to run the offense for a while, he's got much bigger concerns.