1. University of California at Los Angeles, School of Dentistry, Los Angeles, CA 90095, USA
2. University of California at Los Angeles, Jonsson Comprehensive Cancer Center, Los Angeles, CA 90095, USA
3. University of California at Los Angeles, Department of Statistics, Los Angeles, CA 90095, USA
4. Department of Stomatology, Zhongnan Hospital, Wuhan University, Wuhan 430071, China