What Causes Cavities? Written by Website Administrator on July 12, 2012. Posted in FAQs Plaque causes cavities. Bacteria + food & liquids with sugar in them causes plaque (that sticky film in your mouth). Regular brushing and flossing eliminates the plaque. Trackback from your site. Website Administrator This information box about the author only appears if the author has biographical information. Otherwise there is not author box shown. Follow YOOtheme on Twitter or read the blog.