Effect of Organic Ions on Solubility of Enamel and Dentin in Acid Buffers

Acid decalcification is generally accepted as a major factor in caries, and it has been usual to place primary responsibility on lactic acid. Analyses of plaques, saliva, and various material, however, have revealed the existence of acids other than lactic that may be involved in the dissolution of tooth structure. ' 9 These acids, resulting from bacterial fermentation of foods or ingested in the diet, may be present in varying amounts and combinations from one person to another and in a given person from one time to another. At any given acid pH, therefore, plaques, saliva, and carious material may be considered as buffers having hydrogen ion common to a number of anions de-rived from different organic acids. The capacity of these systems to dissolve tooth structure is the sum of the effects due to various ionic and molecular species present therein. Because the pH of such systems is usually not below 4.5, the concentration of hydrogen ion and undissociated acid must necessarily be small relative to the concen-tration of the acid anions. Thus, while hydrogen ion and undissociated acid, acting as a hydrogen ion donor, are important in decalcification, the contribution of the anions to this process cannot be ignored