1. Department of General Dentistry, College of Dentistry, University of Tennessee Health Science Center, Memphis, TN 38163, USA
2. Department of Industrial and Systems Engineering, The University of Iowa College of Engineering, Iowa City, IA 52242, USA
3. Department of Operative Dentistry, The University of Iowa College of Dentistry and Dental Clinics, Iowa City, IA 52242, USA
4. Division of Biostatistics and Computational Biology, The University of Iowa College of Dentistry and Dental Clinics, Iowa City, IA 52242, USA
5. Department of Biostatistics, The University of Iowa College of Public Health, Iowa City, IA 52242, USA
6. Department of Operative Dentistry, Aichi Gakuin University School of Dentistry, Chikusa-ku, Nagoya 464-8651, Aichi, Japan
7. Department of General Dentistry, Creighton University School of Dentistry, Omaha, NE 68102, USA