Initially, you might find some looseness when brushing or flossing, or your dentist may note some wobbling during a routine dental appointment. In certain cases, a loose tooth is caused by advanced gum disease. This is when a bacterial infection affects the gums, tissues, and bones around your teeth. Gum disease is a product of poor oral hygiene. If you do not brush or floss regularly, or if you miss regular dental cleaning, tartar will build up under your gums and cause gum infection.