Dental plaque is a biofilm, usually a pale yellow, that develops naturally on the teeth. Like any biofilm, dental plaque is formed by colonizing bacteria that attach themselves to the tooth's smooth surface.
Once sugars are introduced to plaque, it turns into a tooth eating acid that sits just above the gum line. If regular oral care isn't standard, the acid will start eating at the teeth producing cavities and the plaque will cause gum disease.
Plaque that is allowed to sit for a prolonged period of time can cause cavities, gingivitis, and other problems in your mouth. If it's left longer than that, serious dental procedures may be required to restore your decaying smile.