[1] Univ Calif San Francisco, Sch Dent, Dept Stomatol, San Francisco, CA 94143 USA
[2] Univ Calif San Francisco, Sch Dent, Dept Anat, San Francisco, CA 94143 USA
[3] Univ Calif San Francisco, Sch Med, Dept Stomatol, San Francisco, CA 94143 USA
[4] Univ Calif San Francisco, Sch Med, Dept Anat, San Francisco, CA 94143 USA
[5] Harvard Univ, Sch Med, Joint Program Neonatol, Boston, MA 02115 USA