Sialolithiasis consists of calcified structures in either the salivary gland or ductal system and alteration of salivary gland parenchyma. To investigate the clinicopathological features of sialolithiasis in Korean patients, we selected 60 patients with sialolithiasis diagnosed at the Seoul National University Dental Hospital. Their clinical records and radiographs were reviewed with the analysis of available histologic data from 32 cases. The male to female ratio was 1.1:1. Sialolithiasis is most common between the ages of 20 and 60 years and occurred most frequently in the submandibular gland (97%). Upon microscopic examination, most lesions showed moderate-to-severe inflammatory infiltration and parenchymal changes such as ductal metaplasia, acinar necrosis and fibrosis. Consequently, Korean patients exhibited clinicopathological features similar to those previously reported.

In the previous study it was demonstrated that most of sialolith contained bacterial colonies in their center of calcified laminated capsules1). Although it is still not determined whether the bacterial infection is a major pathogenic cause or not, many authors reported that the bacterial vegetation in sialolith can cause chronic suppurative inflammation in salivary gland. Actually a lot of different bacteria were found in oral cavity, most of them are non-pathogenic as normal flora, and only some of them are pathogenic for different mucosal infectious diseases. However, this study was aimed to identify a causative bacterial strain for the sialolith formation in human salivary gland. A strain of Bacillus subtilis (B. subtilis ) was found in the culture of sialolith, which was known to be a normal flora related to the fermentation of various Korean bean foods. In vitro culture experiment of B. subtilis it abundantly produced the thick biofilm aggregated around their cells and colony structure, which were subsequently attached on the surface of hydroxyapatite( HA) beads in scanning electronmicroscope(SEM) observation. The bacterial adherence on HA beads was strongest in the culture of B. subtilis, followed by Streptococcus mutans (Str. mutans ), oral mixed bacteria, and lactobacillus. Therefore, B. subtilis might be an important causative microorganism for the sialolithiasis in Korean people, and it is suggested that postmeal oral hygiene care should be required to reduce the number of normal flora, B. subtilis, after eating of fermented bean foods.

A patient complaining of severe pain in the right submandibular area showed a huge sialolith in radiogram. During the operation, the submandibular gland was much indurated, and large amount of pus was discharged out at an incision of the salivary gland. The removed salivary gland contained a huge sialolith in the major excretory duct of submandibular gland, which had an intact grayish-white surface in ovoid shape. In the histological examination its excretory ducts were extensively dilated without extravasation of saliva, and the involved salivary gland was almost destroyed by the granulomatous r eaction. Most of a cinar cells were d isappeared and r eplaced by ductal cells filled with exudative materials. The microsections of sialolith showed typical laminar structures of calcification containing amorphous basophilic material in the center, in which a lot of Gram positive and Gram negative microorganisms were found. In the center of sialolith numerous microorganisms were admixed with mucinous materials which were strongly positive for the antibody of mucin-1, and formed multiple colonies. In the periphery of the bacterial colonies proline rich proteins (PRPs) were condensely localized, and followed by the consistent positive reaction of transglutaminase 4 (TGase-4). These data suggest that the sialolith of this study is formed from the primary nidus of bacterial colony aggregated with salivary mucin-1 and PRPs by the crosslinking reaction of TGase-4.