9yr old boy and nail biting

I could really use some specific advise on how to get my 9yr old son to stop biting his nails.
His fingers looked terrible. He has no nails.  His fingers look sore.  He likes to bite his nails while
watching a movie and off an on through out the day.  He'll do it in the car.  He'll do it when he is
bored.  I have painted the liquid on his hands in the past and that has not worked.  I'm to the point
of having him wear gloves in the house.  I don't know what to do. I need to make sure he doesn't ruin his fingers before it's too late.  Please help with specifics.  By the way......there are many children
I see at school with this same problem!  Why are there so many children biting their nails down to
nothing?  Please help!!!  Thank you!!!

[notcreative]

I have the same problem with my 9 year old son.  I too thought of having him wear gloves in the house.  His dad tried that nasty brush on stuff to no avail.  I have tried rewards as well as punishments.  He stopped for a while and his fingers went back to looking great.  I think that kids get some sort of pleasure out of it--from what I have been reading.  This all makes me feel defeated however.  

[albert232]

I have the same problem with my 10 year old son. He plays the guitar and has been told that he needs nails before he can take his next grade. Today I am taking him to have acrylic nails as a one off to hope we can encourage him to grow the overthe summer break. We are using the chane of instant nails and the new guitar sound as he knows the pieces to hopefully strike a chord with him.