Close-up of a person's teeth showing dental plaque deposits revealed using a disclosing tablet, which stains plaque red. Plaque is a mixture of saliva, bacteria and carbohydrates that may build up on the teeth surfaces and around the gum margins as a result of inadequate oral hygiene. If allowed to build-up, plaque eventually forms a hard, calcareous deposit (tartar or calculus) which may invade the gingival spaces between the teeth & gums and cause gum disease (gingivitis) - a condition marked by swollen & bleeding gums. If untreated the disease spreads to and destroys the underlying periodontal membrane & alveolar bone, causing the teeth to loosen and drop out.