The term erosion describes tooth wear caused by acids. Erosions can be a consequence of medical problems like gastroesophageal reflux disease or eating disorders which lead to a regular contact of gastric acid with teeth. These, so called intrinsic erosions occur in such typical locations within the dental arches that even in the absence of other symptoms gastric acid can be assumed to be the cause. Dental professionals may thus be the first to discover and diagnose the underlying medical problem. A good cooperation between the physician and the dentist is consequently necessary for a causal treatment of the patient. Parallel to the therapy of the underlying disease practical dental prophylactic measures like chewing gum und fluoride rinses are recommended.