John M. Powers, PhD, Senior Vice President and Editor, The Dental Advisor, Dental Consultants, Inc., Ann Arbor, Michigan; Professor of Oral Biomaterials, Department of Restorative Dentistry and Biomaterials, University of Texas Dental Branch at Houston, Houston, Texas and John C. Wataha, DMD, PhD, Chair, Department of Restorative Dentistry, School of Dentistry, University of Washington