Shona then practiced as a full time specialist orthodontist in Ballinteer and Kilbarrack Health Centres Dublin for over 5 years gaining a vast wealth of experience treating complex orthodontic cases from the public waiting list including many hypodontia and orthognathic surgical cases. She established Clontarf Orthodontics at 9, Clontarf Road, Dublin 3, in 2002 where she provides a wide range of brace treatments to adults and children.

Dr Leydon continues to work 5 days a week at Clontarf Orthodontics, Dublin 3 and has personally treated thousands of cases over the last 20 years as a specialist. Her areas of particular interest include invisible appliances such as Invisalign and interceptive (early) orthodontics.

Dr Leydon undertakes many advanced courses each year and is an active member of the Irish and American Orthodontic Societies, serving in many roles including Scientific Secretary. Dr Leydon is also a Fellow of the World Federation of Orthodontists. She is a registered orthodontic specialist with the Irish Dental Council and now serves on the Dental Council.