Yes, false teeth can absolutely stain and turn colors over time. When not brushed daily, left-behind food debris and bacteria-filled plaque can create stains that look yellowish-gray, green and even black on teeth. (However, dental implants like crowns and veneers cannot be whitened.) Avoid this scenario by maintaining stellar oral hygiene even when your teeth are false, and brush and soak your dentures regularly while also following the proper steps to clean your dentures.