The gastroesophageal reflux (passage of gastric contents into the oesophagus and the mouth) is the main sign/symptom of a very frequent gastroesophageal reflux disease. Thus, acid regurgitation originates from stomach and it is responsible of the onset of typical symptoms and mucosal injury. Also in oral cavity the noxious acid agent is able to injury oral cavity (soft and hard tissues). These effects are described from international literature, even if a greater interest has shown to date only for hard tissue injury.