ASSEMBLY OF FILM-HOLDING INSTRUMENTS
The instruments used to hold the film parallel to the teeth are plastic bite-blocks, indicator rods, and plastic locator rings.
a. Anterior Instrument. The anterior instrument (see figure 4-19) is assembled and used as follows.
(1) The shielded or printed side of the film packet is placed against the backing support of the bite-block.
(2) It is inserted vertically into the slot by using a downward motion and, at the same time, placing slight pressure against the backing support to open the slot.
(3) There is an embossed dot on the corner of the periapical film. This embossed dot is always placed in a downward position when placing the film into the slot on the plastic bite-block.
(4) The offset position of the indicator rod is held away from the biting surface of the block. The pins are inserted in the proper holes.
(5) The plastic locator ring is fitted onto the indicator rod opposite the film packet.
(6) The assembly is then positioned in the mouth.
b. Posterior Instrument. The posterior instrument (see figure 4-20) is assembled and used as follows:
(1) The shielded, printed or broken side of the film packet is placed against the backing support of the bite-block.
(2) It is inserted horizontally into the slot by using a downward motion and, at the same time, placing slight pressure against the backing support to open the slot.
(3) The embossed dot on the corner of the film is also placed in a downward position when placed in the plastic bite-block.
(4) The right angle portion of the indicator rod is held anterior to the bite-block and away from the film.
(5) The pins are inserted into the proper holes. (The three holes allow a choice for the desired lingual positioning of the film.)
(6) The plastic locator ring is fitted onto the indicator rod opposite the film packet.
(7) The assembly is then positioned in the mouth.