Dr. Gardner was then accepted to Orthodontic specialty training at Wilford Hall Medical Center in San Antonio. After his residency, he served as Chief of Orthodontics at Ft. Campbell, KY, and Director of the Orthodontic section at an Advanced Education in General Dentistry program. He practiced and taught there for several years before becoming Director of Training and Clinical Orthodontics at the Tri-Service Orthodontic Residency Program at the Air Force Postgraduate Dental School in San Antonio. During his 21 years of Army service, he helped train numerous orthodontists, all of which he proudly calls colleagues.

Dr. Gardner is a member of the American Dental Association, American Association of Orthodontists (AAO), American Dental Education Association, and the AAO Society of Orthodontic Educators. He has authored/co-authored articles published in the American Journal of Orthodontics and Dentofacial Orthopedics and the Angle Orthodontist. In his free time, he enjoys boating, fishing, and traveling with his wife and three children.