One of my students turned me on to a nail hardener called "Irene Gari Calcium Base Coat. I creates a beautiful thick coat that lasts long, and really protects your nails.
I just developed a split in my RH thumb nail. I put two thick coats on, and it filled the split top and bottom so full and thick that I cannot even see the split. It's been holding, and I've been playing, and so far it's working great.
If you try it, I think it will fill the ridges and create a smooth surface, and possibly hold the nail together. It's also great for general nail protection.