[1] Univ Pacific, Arthur A Dugoni Sch Dent, Dept Biomed Sci, 155 Fifth St, San Francisco, CA 94103 USA
[2] Univ Pacific, Arthur A Dugoni Sch Dent, Dept Periodont, San Francisco, CA 94103 USA
[3] Univ Calif Berkeley, Coll Letters & Sci, Berkeley, CA 94720 USA
[4] Univ Pacific, Arthur A Dugoni Sch Dent, Program Doctor Dent Surg, San Francisco, CA 94103 USA
[5] Univ Calif Los Angeles, Coll Letters & Sci, Los Angeles, CA 90095 USA