Dental caries is a clinical name for tooth decay. It is a destructive process which causes decalcification of the tooth.
Gingivitis is the inflammation of gums mainly caused by plaque deposits. Gums become red, swollen, and bleed easily.
If gingivitis left untreated it progresses to Periodontitis. It is a severe and irreversible form of gum disease and may destroy the tissues that hold the tooth in the bone. As a result, teeth may become loose.