Mark Johnston, D.M.D, M.S.

Education & Associations

Dr. Mark Johnston graduated from the University of Georgia (UGA), where he received a Bachelor of Science degree in Biology. He entered the Medical College of Georgia in Augusta and received his Doctorate in Dental Medicine (D.M.D.) degree. After dental school, Dr. Johnston continued his education at the University of Alabama at Birmingham (UAB). He completed a Hospital Dentistry Residency, where he received a certificate in Hospital/General Practice Dentistry. Dr. Johnston was a Research Assistant for the Department of Oral and Maxillofacial Surgery. During the same year, he was a Clinical Instructor for the UAB Department of Restorative Dentistry. He completed his three-year orthodontic residency program and received his Master of Science degree and his Certificate in Orthodontics from the UAB School of Dentistry.

Dr. Johnston returned to Atlanta and opened his orthodontic practice in East Cobb. In 2001, Dr. Johnston earned his Board Certification from the American Board of Orthodontics. Only 30% of the orthodontists in the United States are Board Certified.

Dr. Johnston is committed to furthering the future of Orthodontics with his involvement in several dental councils and organizations:

  • Georgia Association of Orthodontists
  • American Dental Association
  • Georgia Dental Association
  • Hinman Dental Society
  • College of Diplomates of the American Board of Orthodontics
  • American College of Dentists
  • International College of Dentists
  • Midwest Component of the Angle Society

Life Outside the Office

Dr. Johnston is very active in his local community. He has been a Partner in Education for Sope Creek Elementary School, Dodgen Middle School, and Dickerson Middle School. Other areas of his involvement include:

  • Dental mission trips with churches to Peru, Mexico and Honduras
  • Eagles Nest - an Atlanta inner-city mission for the homeless
  • Rainbows - an international organization designed to assist children and adults who have experienced loss of a loved one from death or divorce
  • Rotary Club of East Cobb
  • Citizens Advisory Committee for surrounding public schools
  • Coaching various adolescent sports in the community

Dr. Johnston resides in Sandy Springs with his wife, Helene. They have three daughters, Taylor and son-in-law Durham, Chandler, Bailey, and son, Watts. Their house is quite busy with four-legged friends, including three dogs, Pearl, Greta, and Cooper, and one cat, Gary. Dr. Johnston enjoys many hobbies, including hunting, fishing, boating, and spending time in the North Georgia Mountains with his family.

Meet the Team

Dr. Johnston has assembled a team that reflects his values and office mission. The Johnston Orthodontics team works together to provide the best orthodontic treatment to our patients. We treat our patients as we would our family. Our Team goal is to consistently provide the highest quality patient care while focusing on individual patients’ needs.

Our orthodontic team of professionals has more than 100 years of combined experience in providing outstanding orthodontic services to our patients.

Why Choose Us

When it comes to transforming your smile, you want and deserve the very best. So what features set Johnston Orthodontics apart from other practices?
We embrace the latest in orthodontic technology, including clear braces, aligner therapy, and digital scans (no more impressions).
Dr. Johnston has over 30 years of experience treating all types of patients.
Our practice treats all types of patients, regardless of age or orthodontic complexity.
Dr. Johnston is a Board-Certified Orthodontist who develops close working relationships with your general dentist and other healthcare providers to ensure your treatment is fully tailored to your needs.
You get the treatment you need while working within your budget, thanks to our no-interest, flexible payment programs. Plus, we accept direct payment from many insurance providers.
Because your safety and comfort are of the utmost importance, we follow the highest standards for sterilization within orthodontics.
When you choose Johnston Orthodontics, you become part of our family, and we treat you as such. Our office strives to set the bar for professionalism, orthodontic excellence, and client satisfaction.

Two Locations

Wherever you are in East Cobb (Marietta) or Sandy Springs, we are nearby. With two office locations to choose from, it is easy to fit orthodontic care into your schedule. And there is no need to choose one location over the other; Dr. Johnston will see you wherever is most convenient.

Office Tour

East Cobb

Office Tour

Sandy Springs