1. Division of Maxillofacial Prosthodontics Hospital Dentistry Institute; University of Iowa Hospitals & Clinics; Iowa City IA USA
2. Center for Dental Research; Loma Linda University School of Dentistry; Loma Linda CA USA
3. Division of Biostatistics and Research Design; University of Iowa College of Dentistry & Dental Clinics; Iowa City IA USA
4. Department of Prosthodontics; University of Iowa College of Dentistry & Dental Clinics; Iowa City IA USA