Effects of Human Saliva on the Formation of Calcium Phosphate Precipitates in the Presence of Glycyrrhiza and Tannic Acid

Tannins are one of polyphenolic compounds. Polyphenols are classified into two groups in terms of their reaction to gelatin, i.e., hydrolyzable (gelatin-soluble) and polymeric (gelatin-precipitable) polyphenols. They are present in a wide variety of plants used for medicine and food1). Polyphenols are known to form a stable complex with human whole saliva2). They form a complex with proline-rich glycoproteins and histatins3-5). Human saliva is a tannin-binding agent, similar to gelatin, bovine serum albumin (BSA), lysozyme and polyvinylpyrrolidine (PVP)6,7). Therefore, it is expected that the salivary interaction with saliva-soluble and saliva-precipitable tannin may influence oral calcification. Both glycyrrhiza (a herb) and tannic acid affected the formation of calcium phosphate precipitates8). Tannic acid forms precipitates with saliva (salivaprecipitable), but glycyrrhiza does not (salivasoluble)9). Therefore, it is of interest to study the effects of both compounds on the formation of calcium phosphate precipitates in the presence of saliva. Materials and Methods