1. Department of Pediatric Dentistry, The University of Alabama at Birmingham, 1919 7th Ave South, Birmingham, AL 35294, USA
2. Department of Operative Dentistry, School of Dental Medicine, Tsurumi University, 2-1-3, Tsurumi, Tsurumi-ku, Yokohama 230-8501, Japan
3. Department of Microbiology, School of Dental Medicine, Tsurumi University, 2-1-3, Tsurumi, Tsurumi-ku, Yokohama 230-8501, Japan