You should never wear your dentures while you sleep. Failing to remove your dentures while you sleep can result in bad breath and denture stomatitis, also known as oral thrush. Thrush is a condition where your gums become swollen, yeast-infected, and inflamed due to overexposure to bacteria that grows between your gums and dentures, as well as a lack of saliva exposure. Instead of sleeping with your dentures in, soak them in water.