Dental caries (cavities) is tooth decay caused by bacteria in dental plaque. Streptococcus mutans is a gram positive, anaerobic bacterium that causes caries. Pain occurs as the caries progress. Left untreated, caries lead to tooth destruction, infection, and loss of teeth with the need for replacement prostheses. Plaque begins on the tooth surface as a soft film of bacteria, dead cells, and food debris. The plaque eventually mineralizes and hardens to become calculus, also known as tartar. Plaque and calculus irritate the gums and may lead to gingivitis and periondontitis. Calculus is more difficult to remove than plaque and requires removal by a dental hygienist. Prevention of caries includes a healthy diet, regular brushing and flossing, fluoride use, and regular professional cleanings. Source
