Bacterial plaque - a sticky, colorless film that continually forms on the teeth - is thought to be a major cause of gum disease. If you brush your teeth and floss each day to remove plaque, it hardens into a coarse, porous material called calculus (also known as tartar). Germs in the plaque produce and release toxins that stimulate the gums. These toxins cause the fibers that fasten their gums to their teeth to break down, forming a periodontal pocket filled with more toxins and bacteria. As the disease progresses, the pocket is deeper and the bacteria move down until the bone holds the teeth in place. Teeth will eventually fall off or need to be extracted.