1. Department of Orthodontics, Eastman Dental Hospital, London, and at Southend Healthcare Trust, Southend-on-Sea, Essex, U.K.
2. Department of Orthodontics, Southend Healthcare Trust, Southend-on-Sea, Essex, U.K. and at The Royal London Hospital Trust, London, U.K.
3. St Andrew's Hospital, Billericay, Essex and at The Royal London Hospital Trust, London, U.K.