Tooth decay (cavities) is caused from lactic acid, a byproduct from the breakdown of glucose by bacteria, that targets areas, such as pits, grooves, and spots where teeth touch.

                                 Tooth + Bacteria + Sugar = Lactic Acid/Caries (decay)

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Tooth erosion refers to the action of acid on the entire tooth surface.  There are 2 major source of acid that erode teeth:

1. 1. What goes in the mouth - food and beverages have various acidic pH levels.  Foods such as tomatoes, vinegar (acetic acid), fruits (citric acid), yogurt, etc all have low pH levels.  In addition, many drinks contain one or more acids  that are very acidic to teeth.  See pH Chart
   

    Soda pop and energy drinks are a major cause of tooth erosion.

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2.  What comes up into the mouth - Regurgitation also know as “acid reflux” or GERD (gastroesophageal reflux disorder).  Stomach acid (HCl) has a pH of 1.7 - 2.0 and is extremely erosive to teeth.  Typically reflux enters into the oral cavity and attacks teeth closest to the stomach, the back teeth, especially the molars.  (Links to GERD or Acid Reflux Disease)