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.
Dr. Mark Johnston

Dr. Mark Johnston

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. Mark Johnston

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
  • Pierre Fauchard Academy
  • 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 the 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.

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 Aligners (Invisalign, 3M), clear braces, and digital scans (no impressions!)
  • Dr. Johnston is a Board-Certified orthodontist who works closely with your general dentist and other healthcare professionals to ensure a truly customized treatment plan.
  • Our practice specialized in treating all patients, no matter age or orthodontic conditions.
  • Your treatment is affordable. We specialize in low down payments and low monthly payments with little to no interest. We file and accept payment from many insurance providers.
  • At Johnston Orthodontics, we strive to have flexible appointment scheduling that works with your schedule.
  • You can communicate with our office via telephone, text, and email. We endeavor to answer your calls quickly and efficiently.
  • We follow the highest standards for disinfecting and sterilization with the field of orthodontics.
  • Get started the same day. If you feel you are ready to get started, we can often start you the same day—however, no rush, no pressure.

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.

Our 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

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