1. 1 Department of Endodontics and Periodontics; Center for Craniofacial Molecular Biology, Herman Ostrow School of Dentistry, University of Southern California, Los Angeles, CA, USA.
2. 2 Center for Craniofacial Molecular Biology, University of Southern California, Los Angeles, CA, USA.
3. 3 Department of Endodontics and Periodontics, Herman Ostrow School of Dentistry, University of Southern California, Los Angeles, CA, USA.
4. 4 Private practice, El Paso, TX, USA.
5. 5 Private practice, Fullerton, CA, USA.