The procedure I had was to have the sides cut off and an acid chemical swab treatment. I believe there is also a laser treatment available. Because the sides of the nail were cut off and treated I had to do a salt bath everyday for about ten days and apply a salve. Within a month or two the deep groove in the sides of the toes healed and filled in. The nails now appear perfectly normal and only need to be trimmed in the normal fashion of the rest of my nails. Each was reduced by about 1/3.
I am confident that my ingrown toenail problems are over. I wish I had done this 20 years ago.