What is the definition or description of: dental caries?

Dental Caries: Dental caries is another term for tooth decay or dental cavities. Cavities are caused by specific types of bacteria which produce acid that destroys the tooth's enamel and the layer under it, the dentin. Brushing and flossing correctly and regularly will help prevent dental caries.

Tooth disease: It's the illness that occurs in teeth. Almost all adults have had it at some time. For an interesting read: https://en.wikipedia.org/wiki/Tooth_decay

Dental Cavity: Caries is the term dentists use for bacterial tooth decay. Cavities is a commonly used synonym but somewhat less specific.