My husband had a severe accident. he had a major jaw surgery. how long will it take for the numbness in chin and lower lip to go??

Depends: on type of injury ,repair of damaged nerve , location of injury when repaired will regenerate at the of 1mm a day ( approximate ) , in some areas may not regenerate and will be permanent , speak to his doctor for exact out come .

Depends on need: Depends on location and severity of the injury. Full normal sensation may or may not return. Talk to the Surgeon. He/she knows your husband's injury history. Good luck.