1. Conservative Dentistry, University of Hong Kong, Hong Kong SAR, China;
2. Department of Oral Biology and Maxillofacial Pathology, School of Dentistry, Medical College of Georgia, Augusta, GA 30912-1129, USA;
3. Bauru School of Dentistry, University of São Paulo, Brazil; and
4. Bisco, Inc., Schaumburg, IL, USA;