Dental infections are infections that originate at the tooth or its supporting structures and can spread to the surrounding tissue. Dental infections most commonly occur when bacteria invade the pulp and spread to surrounding tissues. Cavities are permanently damaged areas in the hard surface of your teeth that develop into tiny openings or holes. Cavities, also called tooth decay or caries, are caused by a combination of factors, including bacteria in your mouth, frequent snacking, sipping sugary drinks, and not cleaning your teeth well. Streptococcus mutans is the main cause of dental decay. Tooth decay can be stopped or reversed at this point. Enamel can repair itself by using minerals from saliva, and fluoride from toothpaste or other sources. But if the tooth decay process continues, more minerals are lost. A cavity is a permanent damage that a dentist has to repair with a filling.