Abstract: A facebow 10 which has a locking catch 40 mounted to each of the arms 16 and 17 of an inner bow 11. The end portion 13 of each arm 16 and 17 is inserted through a tube 22 of an orthodontic appliance, such as a bracket 15 which is fixed to a respective tooth T. The locking catch 40 includes a hook 42 for engaging the end portion 13 of the arm 16 or 17 which projects distally (rearwardly) of the tube 22. The locking catch 40 is easy for the user to engage and disengage, but when engaged, effectively locks the arms 16 and 17 of the inner bows 11 preventing accidental withdrawal from the respective tubes 22.