In 1994, he was elected by the American Association of Endodontists and served six years as a director of the American Board of Endodontics. He served as secretary of the board for two terms in 1997 and 1998. He was also president of the American Board of Endodontics for two terms in 1999 and 2000.
Dr. Johnson served as an endodontic consultant to the American Dental Association's Council on Materials, Instruments, and Equipment from 1991 to 1995. He was an endodontic consultant to the Commission on Dental Accreditation of the American Dental Association from 1994-2000. In 2004, Dr. Johnson was appointed to serve a three-year term on the Endodontic Advisory Committee for the Commission.
He also has served on the Membership Committee of the International Association for Dental Research and reviews manuscripts for Oral Surgery, Oral Medicine, Oral Pathology, Oral Radiology, and Endodontics; Journal of Endodontics; and Special Care in Dentistry. Dr. Johnson is a member of Omicron Kappa Upsilon, and a fellow in both the International College of Dentists and American College of Dentists.
Following two years of active duty with the U.S. Army at Fort Still, Oklahoma, Dr. Johnson was an active member of the 294th Medical Detachment of the Iowa Army National Guard from 1977 to 1996 and holds the rank of brigadier general (retired). In 1993 Dr. Johnson was awarded the "A" Proficiency Designator, the highest award for professional achievement given by the Office of the Surgeon General, United States Army. He currently serves as a consultant to the Advanced Education Programs in Endodontics for the Army (Fort Gordon) and the Navy (Bethesda).
Dr. Johnson is the editor of a recently published endodontic textbook entitled Color Atlas of Endodontics. The book, which is published by W.B. Saunders, features over four hundred clinical photographs and color drawings, and also contains twelve chapters authored by thirteen different authors. The book has been translated into Italian (Verduci Editore, Rome, Italy) and Korean (Daehan Publishing, Seoul, Korea). He has lectured on the state, national, and international levels in addition to authoring numerous book chapters and scientific manuscripts. Dr. Johnson is the senior author of the obturation chapter in Pathways of the Pulp, the isolation and endodontic access chapter as well as the cleaning and shaping chapter in the new Principles and Practice of Endodontics.
In 2006, Dr. Johnson was named the Richard E. Walton Professor of Endodontics at the University of Iowa College of Dentistry.
Administrative Activities: Head of the Department of Endodontics.
Teaching Activities: Dr. Johnson directs the preclinical sophomore laboratory and teaches in the junior endodontic clerkship and Family Dentistry.
Clinical Activities: Dr. Johnson participates in the College of Dentistry's dental service plan and is a consultant to the Veterans Administration Hospital in Iowa City.
National or International Professional Appointments or Activities: Dr. Johnson has served as chair (1993-1994) and councilor (2000-2003) of the Endodontic Section of the American Dental Education Association. He currently represents the American Association of Endodontists (AAE) on the Council of Hospitals and Advanced Education Programs of ADEA.