R.R.
you don't say how old your son is. If most of his growth is complete, I highly recommend the surgery. It is in office and solves the problem permanently. Cutting a "v" will not help, as it is the nail bed that causes the growth, and the nail will not grow to fill in the V - it is a myth. (No offense, previous poster) - see this article... http://www.epodiatry.com/ingrown_nails.htm
I had a very large nailbed and horrible, very painful ingrown toenails as a child and tried every trick in the book, and no matter how careful I was, it always came back. It was because my nailbed was too large and mishapen. When I was 18, I had the surgery, where the dr cauterized the nailbed beside the toe, and no more large, ingrown toenails! Very, VERY worth it.
Two of my now adult children inherited my bad toenails and had the surgery when they were also 18. Our toes all look normail now.