Upper: For narrow toothed jaws Horseshoe shaped device made of metal or plastic used to carry dental impression material to the mouth, to confine the material in opposition to the surfaces to be recorded (e.g., teeth and gums), and to control the impression material while it sets to form an impressi..
It is plastic material in form of particles or pieces used to increase size of impression tray in any direction.
It is also used to fabricate customize impression tray for difficult patients...