Ralph DeLong, PhD, DDS, MS

Professor Emeritus, Department of Restorative Sciences

Ralph DeLong

Contact Info


Office Phone 612-625-1409

Fax 612-626-1484

Office Address:
16-212 Moos Tower
515 Delaware St. SE
Minneapolis, MN 55455

PhD, University of Minnesota (Nuclear Physics), 1974

MS, University of Minnesota (Fixed and Removable Prosthodontics), 1981

BS, University of Nebraska (Physics and Mathematics), 1966

DDS, University of Minnesota (Clinical Dentistry), 1978


Dr. DeLong is a Professor Emeritus in the Department of Restorative Sciences, and a member of the Minnesota Dental Research Center for Biomaterials and Biomechanics (MDRCBB).

Dr. DeLong's expertise in physics and dentistry led to the development of A.R.T. (Artificial Resynthesis Technology), an oral simulation environment, which is often referred to as the "Artificial Mouth." The Journal of Research & Development chose it as one of the 100 most significant new technical products of the year. Along with co-developer, Dr. William H. Douglas, Dr. DeLong received the "I.R. 100 Award" for the development of a "Biomaterials Evaluation System (Oral)" in 1983.

Dr. DeLong also developed a software program, AnSur? (Reagents, Univ. of MN), that could take data from a 3D surface digitizer and use it to measure surface changes with time. The addition of an optical digitizer spurred the development of the "Virtual Dental Patient" (VDP). In 1997, Dr. DeLong received a NIH/NIDCR grant to test the hypothesis that a virtual computer rendition of a dental patient (VDP) and its clinical source are closely correlated over a wide range of clinical conditions.

In 2004, Dr. DeLong became the Director of the Minnesota Dental Research Center for Biomaterials and Biomechanics (MDRCBB). Established as an industrial/academic collaboration, with the 3M Foundation and 3M Dental Products Division providing the founding funds, the MDRCBB works with industry on the development of new dental biomaterials. New materials are evaluated using technologies in the MDRCBB to determine their applicability and chances for clinical success in the oral cavity. The MDRCBB has been continuously funded since 1991.

Awards & Recognition

  • Member, Phi Kappa Phi Honorary Society
  • Member, Omicron Kappa Upsilon Honorary Dental Society
  • I.R. 100 Award, Journal of Research and Development, 1983
  • Fellow, Academy of Dental Materials


Research Summary/Interests

The Virtual Dental Patient - Patient specific, accurate 3D representations of articulated upper and lower jaws and their relative movements.

Clinical measurement using 3D digitizing and computer graphics

Robotics and its application to simulation of an artificial oral environment


  • Versluis, A., Tantbirojn, D., Pintado, M.R., DeLong, R. and Douglas, W.H. Residual shrinkage stress distributions in molars after composite restoration. Dent. Mater. 20: 554-564, 2004.
  • Tantbirojn, D., Versluis, A., Pintado, M.R., DeLong, R. and Douglas, W.H. Tooth deformation patterns in molars after composite restoration. Dent. Mater. 20: 535-542, 2004.
  • DeLong, R., Heinzen, M., Hodges, J.S., Ko, C.C. and Douglas, W.H. Accuracy of a system for creating 3D computer models of dental arches. J. Dent. Res. 82: 438-442, 2003.
  • Chang, M.C., Ko, C.C., Liu, C.C., Douglas, W.H., DeLong, R., Seong, W.J., Hodges, J. and An, K.N. Elasticity of alveolar bone near dental implant-bone interfaces after one month's healing. J. Biomech. 36: 1209-1214, 2003.
  • Ko, C.C., Douglas, W.H., DeLong, R., Rohrer, M.D., Swift, J.Q., Hodges, J.S., An, K.N. and Ritman, E.L. Effects of implant healing time on crestal bone loss of a controlled-load dental implant. J. Dent. Res. 82: 585-591, 2003.
  • DeLong, R., Ko, C.C., Anderson, G.C., Hodges, J.S. and Douglas, W.H. Comparing maximum intercuspal contacts of virtual dental patients and mounted dental casts. J. Prosthet. Dent. 88: 622-630, 2002.
  • DeLong, R., Ko, C.C., Olson, I., Hodges, J.S. and Douglas, W.H. Helical axis errors affect computer-generated occlusal contacts. J. Dent. Res. 81: 338-343, 2002.
  • Ko, C.C., Swift, J.Q., DeLong, R., Douglas, W.H., Kim, Y.I., An, K. N., Chang, C. H. and Huang, H. L. An intra oral hydraulic system for controlled loading of dental implants. J. Biomech. 35: 863-869, 2002.
  • Lai, J.H., Wang, L.L., Ko, C.C., DeLong, R. and Hodges, J.S. New organosilicon maxillofacial prosthetic materials. Dent. Mater. 18: 281-286, 2002.
  • DeLong, R., Pintado, M.R., Ko, C.C., Hodges, J.S. and Douglas, W.H. Factors influencing optical 3D scanning of vinyl polysiloxane impression materials. J. Prosthodont. 10: 78-85, 2001.
  • Pintado, M.R., DeLong, R., Ko, C.C., Sakaguchi, R.L. and Douglas, W.H. Correlation of noncarious cervical lesion size and occlusal wear in a single adult over a 14-year time span. J. Prosthet. Dent. 84: 436-443, 2000.


Board Certifications

Board Qualified by American College of Prosthodontists, 1981