What you’re worried about: That you’ve been reintroducing old bacteria into your mouth, or perhaps that you’ve actually been undoing all those months of faithfully flossing. Omg, have you been gradually yellowing your pearly whites all this time?
The very worst that could happen: Periodontal disease and tooth loss, due to a major buildup of plaque, says Melissa Thompson, DMD, who owns three Aspen Dental practices in Massachusetts. Over time, she explains, the firm bristles get frayed and become incapable of clearing the areas between the teeth and the plaque resting on each tooth’s surface. “Plaque not only causes cavities, but when it’s not removed from around the gum line, can cause inflammation and irritation leading to gingivitis or gum disease. If gingivitis is not treated, it can progress to periodontal disease and, possibly, tooth loss.”
What will probably happen: Some plaque buildup, but your toothbrush will probably become so frayed and unappealing that you’d almost always replace it before you did any real damage, says John Grbic, DMD, professor and director of the division of oral biology at Columbia University College of Dental Medicine. “A well-functioning toothbrush has bristles that bend,” he says. “When your brush is old, it’s hard not to notice,” he says.