In 1942, Dr. Harry Coover of Kodak Laboratories developed the forerunner of super glue-cyanoacrylates. He first demonstrated the bonding strength capabilities of super glue on "I've Got A Secret" in 1959. During the Vietnam War, field medics used super glue under battlefield conditions to stop bleeding and even close some wounds.
Over the years, I have found that if I use a nail file to smooth the area where the crack is appearing, the crack can lessen. I then disinfect the crack, cut or scrape, and then coat the area with a drop of super glue. It may sting a bit, but the area is sealed. I continue to file and super glue the area for a few days until crack is gone, compared to 7-10 days it took to heal before I started doing this.