The prevalence of gastro-esophageal reflux disease (GERD), as well as that of dental erosion (DE), increases steeply in the 21th century societies of Europe and North America. GERD is a multicausal disease, with genetic, anatomical and neurological insufficiencies in the background, complemented with behavioral factors. In GERD, as reflux occurs more often and lasts longer than physiologically, the result is esophagitis and supraesophageal manifestations. The acid, which might even reach the mouth, interacts with the material of the teeth and demineralization, a form of dental erosion takes place. Clinical studies have proved, that in patients suffering from GERD dental erosion takes place significantly more often than in patients who do not. It was also confirmed that in patients with idiopathic dental erosion GERD is significantly more frequent than in the "uneroded" population. These data suggest that in case of extended dental erosion the dentist should think of a - possibly not yet diagnosed - gastroenterological disease.