The extrinsic causes of dental erosion can be grouped under the headings of environmental, diet, medications and lifestyle. Environmental factors mainly involve exposure to acid fumes by workers in factories without proper safeguards. Swimming pools with low pH due to inadequate maintenance have also been implicated. Dietary factors have received the most attention and are likely to affect the broadest segment of the population. Most acidic foods and drinks have the potential to cause dental erosion in the human mouth. The total acid level (titratable acid) of dietary substances is considered more important than their pH, because it will determine the actual H+ available to interact with the tooth surface. Other constituents of foods and beverages will also have a modifying effect, including the calcium, phosphate and fluoride concentration, the acid type, and physical and chemical properties that influence the clearance rate from the mouth. It is not appropriate to assign relative degrees of risk to the different dietary substances except in general categories, because of the many human biological and behavioral factors that influence the clinical expression of dental erosion. The types of foods and beverages consumed, and the frequency and time of consumption are lifestyle factors that are considered most important regarding the clinical development of dental erosion. Low pH medications and oral hygiene products have also been suggested as potential causes of erosion. The combination of frequent consumption of acidic substances and overzealous oral hygiene practices may be another high risk lifestyle factor.