Film-Holding Devices For Intraoral Radiographs

Film-Holding Devices For Intraoral Radiographs

Write short note on film holders.
Answer. These are also known as film-holding devices.

Types of Film holders

• Blade type
  • Throat stick
  • Acrylic blade with slot
  • Snap-A-ray.
• Bite Block
  • Styrofoam block
  • Snap-A-ray.
  • Artery forceps with bite block.
• Positioning indicating device
  • Rinn XCP (extension cone paralleling) with normal or rectangular collimator.
  • Precision X-ray holder.
• Snap–A–Ray Film Holder
  • It is a simple plastic film holder which can be used in both anterior and posterior region of oral cavity.
  • It does not consists of film backing with it so the film can band and cause image distortion.
  • It is very useful as it can be used in the mouth of patients who cannot tolerate film backing.

Dental film holders

• Fitzgerald Hemostat
  • This hemostat comes complete with a rubber bite block and suitable metal film backings.
  • It is especially useful in patients who have a limited degree of mouth opening.
  • Patient retains the forceps within the mouth by biting against the rubber bite block.
  • After the patient bites on the rubber bite block, the film and the film backing are rotated until it is parallel to the long axis of the teeth being radiographed.
  • Film should be placed against the palate, and usually parallel to the midline.
• Bite Blocks
  • They are used for the anterior teeth and mandibular premolars.
  • In the anterior projection, the film is inserted into the slot in the small end of the wooden bite block and the patient bites on the large end of the film block while in case of the mandibular anterior and premolar, the film is inserted in the slot in the large end of the block and the patient bites on the small end of the block.

Film holders in dental radiography

• Rinn XCP Instruments
  • This is a set of two instruments—an anterior and a posterior instrument.
  • Each instrument consists of three parts, i.e.
    • Anterior and posterior bite blocks: These are designed to retain the film packet by means of tension created by a semiflexible plastic backing.
    • Indicator rod: These are made of stainless steel and are used to align the X-ray cone with the film. There is an anterior rod offset and a posterior right-angled rod designed to insert into the receptacle holes of the respective bite blocks.
    • Locator ring: They are made for sliding into the rod to establish alignment of the cone and rectangularshaped extension cone with the film. This also prevents “cone-cutting”.
  • Rinn XCP instruments have been modified to include a rectangular, shaped locator ring which can be rotated on its own axis.
  • This decreases exposure to the patient and also simplifies cone and film alignment.

Snap-a-ray film holder

Advantages of Film Holders

• These offer protection to the patient because their use often reduces the frequency of retakes, as the film can be positioned more accurately in the patient’s mouth.
• They also provide an external guide to indicate the film’s position.
• The possibility of misaligning the X-ray tube and partially missing the film (cone-cut), is also reduced.
• Some of the holders also collimate the beam to the size of the film being used, which further reduces patient exposure.
• The exposure to the patient’s fingers is also reduced, as the patient does not have to hold the film.

Positioning devices for intraoral films

Disadvantages of Film Holders

• Due to the presence of the bite block resting upon the teeth, the film may not extend far enough beyond the apical region to allow any latitude for examination of the apical tissues and structures.
• The mouth closing over the block prevents the operator from checking the position of film in the mouth.
• It is difficult to angulate the tube to meet abnormal conditions. In many cases, exposures with the use of film holders result in distortion of the teeth.