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.

Ⅰ. INTRODUCTION
 Ⅱ. MATERIALS AND METHODS
 Ⅲ. RESULTS
 Ⅳ. DISCUSSION
 Ⅴ. REFERENCES

• 김연숙(Department of Dental Hygiene, Cheongju University) | Yeon Sook Kim correspondence