Dental caries is a progressive bacterial infection that causes damage to teeth. It is caused by an interaction between cariogenic bacteria like Streptococcus mutans, fermentable carbohydrates like sugar, and the bacteria's ability to produce acid that demineralizes enamel. The demineralization can progress and destroy dentin, eventually reaching the pulp and causing inflammation if left untreated. Clinical signs include cavities and pain from hot or cold stimuli. Advanced dental caries can spread infection beyond the tooth and cause serious health issues if not addressed.