Dr Clark developed the Twin Block Technique in 1977 in his orthodontic practice in Scotland.  The technique is now the most widely used functional technique throughout the world.

In 2004 Dr Clark developed invisible TransForce Appliances for arch development. They are very efficient in improving arch form and providing space to correct irregularity of the anterior teeth. Contact www.orthoorganizers.com

Dr Clark is the first recipient of an award of distinction from the British Orthodontic Society for an outstanding contribution to the specialty of orthodontics. In 2008 he received the first award from IFUNA for personal outstanding international service to functionalism and orthodontics.