Soft drinks - even diet drinks, sports drinks, and fruit drinks that are low in sugar or sugar free - include acids that can damage teeth. The American Association of Orthodontists has prepared a list of the pH levels of more that 30 popular beverages.
According to the AAO, the acid in soft drinks pulls the calcium out of enamel. Such decalcification can lead to cavities. When soft drinks also include sugar, the risk of cavities increases. The sugar interacts with plaque and forms another acid to further dissolve the enamel, and when the enamel is gone, the loss is permanent.
The dangers are particularly troublesome for orthodontic patients. Brackets protect the portions of the teeth that they cover, but decalcification can occur on the uncovered portion of the tooth.
The AAO also encourages patients to refrain for drinking soft drinks while wearing aligners or retainers. Liquid can seep into them and stay there until they are removed. If the liquid contains acid, the prolonged exposure accelerates damage to the teeth.
Realistically, we recognize that patients may indulge in soft drinks for an occasional treat. All patients who consume such beverages should drink them through a straw to minimize acid contact with their teeth. They should brush and floss right away, or at the very least, rinse with water.