This course establishes the concept of dental erosion as a condition that is distinct from caries, and as an emerging public health issue with increasing prevalence in people of all ages. Although often generalized under the heading of “tooth wear,” there are actually two distinct tooth surface loss processes that must be taken into account. Tooth surface loss can be the result of physical mechanisms, such as attrition and abrasion, or chemical mechanisms triggered by acid. Both of these mechanisms are discussed, as well as the chemical, biological, and behavioral factors that increase or reduce risk of tooth surface loss. For the purpose of this discussion, the impact of physical processes on tooth surface loss, such as attrition and abrasion, will be referred to as tooth wear. The process related to chemical acid attack resulting in tooth surface loss will be referred to as dental erosion. In addition, diagnosis and prevention measures related to dental erosion are introduced.