Dental caries is one of the most common infectious diseases. Although its prevalence has declined significantly in many countries, dental caries in Korea remains a public health concern. The essential process in dental caries involves demineralization of the tooth surface due to a lowered pH in dental plaque, which contains various microorganisms. Streptococcus mutans is believed to play a major role in the development of dental caries by producing high concentrations of organic acids. This study aimed to evaluate the cariogenic potential of the lytic enzyme L27, derived from Bacillus licheniformis YL-1005, isolated from Korean soil. Enzyme L27 was not cytotoxic to normal periodontal ligament cells at concentrations below 250 μg/mL and had minimal impact on the pH changes caused by S. mutans . Calcium ion release occurred slowly and progressively during the first 20 minutes, but demineralization was significantly inhibited by L27. The attachment of S. mutans to hydroxyapatite beads and the reduction in surface hardness were also significantly inhibited, although the rate of bacterial attachment decreased over time. Taken together, these findings suggest that the lytic enzyme L27 from soil-derived bacteria exhibits anticariogenic effects by preventing bacterial attachment to the enamel surface and inhibiting demineralization.

Introduction
Materials and Methods
    1. Bacterial culture and preparation of lytic enzyme
    2. Preparation of saliva
    3. Radiolabeling of S. mutans with [3H]-thymidine
    4. Evaluation of cytotoxicity of the lytic enzyme
    5. Measurement of Ca2+ concentration and pH in theartificial mouth model
    6. Effect of the lytic enzyme on demineralizationinduced by S. mutans
    7. Adhesion assay of S. mutans to HA beads
Results
    1. Cytotoxicity of the lytic enzyme
    2. Effect of the lytic enzyme on pH changes inducedby S. mutans
    3. Effect of the lytic enzyme on Ca2+ release inducedby S. mutans
    4. Effect of the lytic enzyme on the adhesion ofS. mutans to HA beads
Discussion
Funding
Conflicts of Interest
References

• Ji-Young Park(Interdisciplinary Program of Perfume and Cosmetics, Chonnam National University, Gwangju 61186, Republic of Korea)
• Suk-Gyun Park(Department of Oral Microbiology, School of Dentistry, Chonnam National University, Gwangju 61186, Republic of Korea)
• Seung-Ho Ohk(Department of Oral Microbiology, School of Dentistry, Chonnam National University, Gwangju 61186, Republic of Korea) Corresponding author