Our Office

Timonium Dentistry was established in 1979 by Dr. Knopf and Dr. Ballinger who began working together while serving in the Army Dental Corps.

Our office is located in the Kelly Building at 20 East Timonium Rd., Suite 300, in Timonium, MD. We are next to Timonium Square and across the street from the Maryland State Fairgrounds.

If you would like to make an appointment or have any questions, please contact our office directly.


Dr. Mark Ballinger

Dr. Mark Ballinger is a native of New Prague, Minnesota. He attended St. John’s University in Minnesota and was awarded his D.D.S. degree in 1969 from the University of Minnesota. Upon completion of his dental degree, He completed a 2 year residency in general dentistry and went on to serve ten years on active duty in the U.S. Army Dental Corps. After resigning from active duty, Dr. Ballinger completed another 17 years in the Army Reserve and retired with the rank of Colonel.

In 1979, Dr. Ballinger established this dental practice with Dr. David Knopf, with whom he served in the Army Dental Corps. Throughout his career, he has pursued excellence in all areas of dentistry, with an emphasis on cosmetic restorative care. Continuing education in Invisalign orthodontic therapy, implants, and laser dentistry have broadened the scope of his general practice. In recent years, he has sought extensive training in the rapidly evolving field of dental sleep medicine, which he believes to have an incredible potential to improve the health and well being of patients living with obstructive sleep apnea.

Dr. Ballinger has been voted a Baltimore Magazine top general dentist six times and is an active member of the American Dental Association.


Dr. Thomas Stack

Dr. Thomas Stack is passionate about improving the oral health of his patients. He is grateful for the opportunity to use his technical skill and medical knowledge to help others in an exciting and rapidly evolving field. Upon completing his doctorate of dental surgery at the University of Maryland, he completed a general practice residency at Christiana Hospital the following year. Seeking to better serve his community, Dr. Stack then served in the National Health Service Corps for six years, primarily as the director of a clinic in downtown Baltimore providing dental care to the homeless population. Outside of his professional career, Dr. Stack continues to deliver care to the underserved as much as possible. He has travelled extensively with dental service organizations, providing care in Mexico, Kenya, the Dominican Republic, as well as underserved areas of the United States (please click on the hyperlinks to learn about how you can aid these organizations in their missions). Regardless of location, Dr. Stack is devoted to pursuing the highest level of dental care possible for his patients. He is relentless in the pursuit of advanced dental education to expand his knowledge and skill in order to offer the best available treatment options. Even as technology progresses, Dr. Stack understands that there is no substitute for building caring relationships with his patients and staff, which he believes are essential to achieving great oral health. Outside of dentistry, Dr. Stack likes to stay active by running, cycling, swimming and climbing. He also enjoys spending time at home with his wife, Jessica and their fluffy cat, Georgie.


Dr. David Knopf

Dr. David Knopf was raised in New Haven, Connecticut. He received both his undergraduate and dental degrees from the University of Pittsburgh, being awarded a D.M.D. in 1973. Dr. Knopf spent 7 years on active duty in the U.S. Army Dental Corps completing both a 1 year general dentistry residency and a Master’s of Education awarded by the University of Southern California. Upon completion of active duty, Dr. Knopf continued as a reserve officer and the commander of a 60 man reserve dental unit retiring in 1996 as a Ltc.

Dr. Knopf established this dental practice in 1979 with Dr. Mark Ballinger, with whom he served in the Army Dental Corps. He has provided comprehensive general dental care in this community since that time. His continuing efforts in dental education have added layers of complexity and additional skills in all areas, including cosmetic dentistry and endodontics.

Dr. Knopf has served on the peer review committee for the Baltimore County Dental Association and has adjudicated cases brought before the Maryland Sate Dental Association. He is active in the American Dental Association and the Academy of General Dentistry.