Twin Block
A specific two-part removable functional appliance designed by William Clark to advance the mandible and correct Class II skeletal discrepancies during growth.
Full Definition
The Twin Block appliance consists of upper and lower removable acrylic plates with interlocking bite blocks angled at 70°, which posture the mandible in a forward position during both function and rest. It is one of the most commonly used functional appliances in contemporary UK orthodontics and is particularly effective during the adolescent growth spurt. 'Twin Block' is a proper noun and should always be capitalised. Editors must not lowercase it or merge it into 'twinblock'. The device is often contrasted in clinical literature with fixed functional appliances such as the Herbst.
Usage
Usage note: Always written as two capitalised words: 'Twin Block'. Do not write 'twin block', 'Twin-Block', or 'twinblock'. As a named appliance, it functions as a proper noun.
In Context
- "The patient was prescribed a Twin Block to be worn full-time including during eating." — Appliance fitting record
- "After nine months of Twin Block therapy, the overjet had been reduced from 10 mm to 3 mm." — Orthodontic progress report