Walk into the ER in Bethlehem, Pa., with a toothache, and you could walk out with a plug of Super Glue in your mouth. Doctors there may squirt your damaged tooth with the medical version of the stuff called Dermabond, sold by Johnson & Johnson and approved by the FDA to close wounds.

The business end of the sticky stuff is cyanoacrylate, the key chemical in Super Glue and Krazy Glue that you might have in your toolbox. A tiny dab of glue brought quick pain relief when doctors used it to seal the cavities of patients who showed...