Gum disease is an infection of the tissues that surround and support your teeth. It is a major cause of tooth loss in adults. Because gum disease is usually painless, you may not know you have it. Gum disease is caused by plaque, the sticky film of bacteria that is constantly forming on our teeth. Some warning signs that can signal a problem include gums that bleed easily; red, swollen, and tender gums; receding gumline; and persistent bad breath. See your dentist if you suspect you have gum disease because the sooner you treat it the better.