Sialolithiasis: mechanism of calculi formation and etiologic factors.

BACKGROUND Sialolithiasis is a common disease of salivary glands. The etiology of these calculi is little known and their exact mechanism of formation is unknown. METHODS The composition and structure of 21 sialoliths were studied and the composition of the saliva of each corresponding patient was determined (pH, calcium, magnesium, phosphorus, citrate and phytate). RESULTS Eighteen sialoliths exhibited similar macro and microstructure, being constituted by hydroxyapatite (HAP) and organic matter, normally arranged in a multilayer structure. The three remaining sialoliths were exclusively constituted by organic matter. The salivary Ca of patients with HAP calculi was significantly higher than that found in the saliva of the healthy group. The salivary phytate concentration of patients with HAP calculi was significantly inferior to that found in patients with calculi exclusively formed by organic matter, as well as to that found in saliva of healthy group. Significant differences between the salivary magnesium concentrations of patients with HAP calculi and the control group were also observed. No significant differences between pH and citrate concentrations of the three groups were found. CONCLUSIONS It was concluded that the deficit of crystallization inhibitors such as myo-inositol hexaphosphate (phytate) was also an important etiologic factor implied in the sialolith development.