Dr. Garretson received his Doctor of Dental Surgery degree in 1989 from the University of Texas Health Science Center at San Antonio, Dental School. Since 2004 he has limited his practice to endodontics. In past years he has lectured on a regular basis at the UT dental school to AEGD post-doctoral residents on a variety of endodontic topics. Dr. Garretson has been an active member in several international online education forums, and has authored articles published in the Roots International Journal and the International Dental Tribune.
He also sits on the endodontic editorial review board for Reality publishing, and has worked with dental instrument manufacturers developing and evaluating endodontic equipment and techniques. He is a member of the ADA and an associate (non-specialist) member of the AAE and does volunteer dentistry at the San Antonio Christian Dental clinic.