1. Chapter 7
Dental X-Ray Film

2. Dental Radiography Questions
What is dental x-ray film composed of and how does it work?
What different types and sizes of x-ray films are used in dentistry?
What are the differences between intraoral and extraoral film?

3. Dental Radiography
Chapter 7 Reading:
Iannucci & Howerton (pp )

4. Dental Radiography Chapter 7 Outline Dental X-Ray Film
Dental x-ray film composition and latent image
Types of dental x-ray film
Film storage and protection

5. Introduction Purpose Iannucci & Howerton (pp. 63-64)
To define film composition
To detail latent image formation
To describe the types of intraoral, extraoral, and duplicating film used in dental radiography
To discuss film storage and protection
Why is it so important to use the correct terminology?

6. Dental X-Ray Film Composition and Latent Image
Iannucci & Howerton (pp. 64)
Dental x-ray film serves as a recording medium or image receptor.
Image: a picture or likeness of an object
Receptor: something that responds to a stimulus
What is the latent image?

7. Film Composition Dental x-ray film has four basic components:
Iannucci & Howerton (p. 64)
Dental x-ray film has four basic components:
Film base
Adhesive layer
Film emulsion
Protective layer
Why is the film base a necessary component of the film composition? (The chemical crystals are embedded in the film base.)

8. Film Base A 0.2 mm-thick piece of polyester plastic
Provides strength and stable support for the delicate emulsion
The film base is constructed to withstand heat, moisture, and chemical exposure.
The film base is transparent and exhibits a slight blue tint that is used to emphasize contrast and enhance image quality.

9. Adhesive Layer Attaches the emulsion to the base
The adhesive layer covers both sides of the film base.
It is added to the film base before the emulsion is applied.

10. Film Emulsion
A homogenous coating with a mixture of gelatin and silver halide crystals attached to both sides of the film base
Gelatin
Used to suspend and disperse millions of microscopic silver halide crystals over the film base
Halide crystals
The silver halide crystals absorb radiation during exposure and store the energy
Why are there two emulsion layers on intraoral films? (This allows an image to be produced using less radiation.)
A halide is a chemical compound that is sensitive to radiation or light.

11. Protective Layer
A protective layer is a thin coating over the emulsion to protect the emulsion from damage.
It protects the emulsion surface from manipulation as we as mechanical and processing damage.

12. Latent Image Formation
Iannucci & Howerton (pp )
Silver halide crystals contain various levels of stored energy, depending on the density of the objects in the area exposed.
The stored energy forms a pattern known as the latent image.
The latent image cannot be seen until chemical processing to produce a visible image.

13. Latent Image Formation
Iannucci & Howerton (pp ) (Figs. 7-3, 7-4)
When photons strike the emulsion, some silver bromide crystals are exposed while others are not.
The crystals that are exposed are ionized, and the silver and bromine atoms are separated.
Irregularities in the lattice structure of the exposed crystal, sensitivity specks, attract the silver atoms.
These aggregates of neutral silver atoms are known as latent image centers.
An example of another type of latent image is fingerprints. If you touch any item, you leave your fingerprints even though you cannot see them on that item. When that item is treated, your fingerprints become visible.

14. Types of Dental X-ray Film
Iannucci & Howerton (pp )
Intraoral film
Extraoral film
Duplicating film
Which of these three x-ray films is the most commonly used? (Intraoral.)

15. Intraoral Film
Placed inside the mouth and used to examine the teeth and supporting structures
How do skilled dental radiographers reduce the patient’s exposure to x-rays? (By reducing the number of retakes.)
Why does the film need to be protected from the light? (Light is a form of radiation and will expose and ruin the film.)
Light cannot pass through the packet, but x-rays can.
The terms “film” and “film packet” are often used interchangeably.

16. Intraoral Film Packaging
Iannucci & Howerton (p. 65)
Used to protect the film from light and moisture
It is usually available in plastic trays or cardboard boxes containing 150 films.
Boxes are labeled with the type of film, film speed, film size, number of films per packet, total number of films enclosed, and the expiration date.
Why do some packets contain two films? (This allows for a copy to be made instantly when it is known that a copy will be needed, such as with certain insurance claims or specialty referrals.)

17. Intraoral Film Packaging
Iannucci & Howerton (pp )
Film packets have four components
X-ray film
Paper film wrapper
Lead foil sheet
Outer package wrapping
Film packets protect the film from light and moisture.

18. X-Ray Film One or two double emulsion film packet
Identification dot used to determine film orientation
Double-emulsion film is used instead of single-emulsion film because it requires less radiation exposure to produce an image.
The identification dot is used for film orientation.

19. Paper Film Wrapper
A black protective sheet to cover the film and protect it from light

20. Lead Foil Sheet
Located behind the film wrapped in black protective paper
Shields the film from back scattered (secondary) radiation that creates film fog
Has a pattern that is visible on a reversed film
What purpose does the lead foil serve? (The lead foil protects the film from back-scattered radiation.)
What would happen if the lead foil was not there? (The back-scattered radiation would fog the image.)

21. Outer Package Wrapping
Iannucci & Howerton (pp )
Soft vinyl or paper to seal the contents and protect them from light or moisture
Tube side
Solid white with a raised bump corresponding to the identification dot on x-ray film
This side should face the tubehead during an exposure.
Label side
Color coded to identify between one and two film packs and according to film speed
Has a flap used to open the film packet before processing.
What information is printed on the label side of the film packet? (A circle or dot that corresponds with the raised identification dot on the film, the statement “opposite side toward tube”, the manufacturer’s name, the film speed, and the number of films enclosed.)

22. Intraoral Film Types Periapical film Bite-wing film Occlusal film
Iannucci & Howerton (pp )
Periapical film
Bite-wing film
Occlusal film

23. Periapical Film
Used to examine the entire tooth and 2 mm. of supporting bone
The term periapical is derived from the Greek word peri meaning “around,” and the Latin word apex, referring to the terminal end of a tooth root.
This type of film shows the tip of the tooth root and surrounding structures as well as the crown.

24. Bite-Wing Film
Used to examine the crowns of both maxillary and mandibular teeth on one film
Used for examining interproximal surfaces
Can use stick-on tabs of bite-wing loops
The bite-wing film has a “wing,” or tab, attached to the tube side of the film.
Bite-wing films are helpful in detecting cavities in between the posterior teeth.

25. Occlusal Film
A larger film used for examination of large areas of the maxilla or mandible
This film was named occlusal because the patient “occludes,” or bites on, the entire film.

26. Intraoral Film Sizes Five sizes are available: 0, 1, 2, 3, 4.
Iannucci & Howerton (p. 68)
Five sizes are available: 0, 1, 2, 3, 4.
Periapical film
Bite-wing film
Occlusal film

27. Periapical Film 0: used for small children
1: used for anterior teeth in adults
2: standard film, used for anterior and posterior teeth in adults
Size #2 film is typically used for both anterior and posterior views because it will give a wider image that will overlap adjacent images. This allows for areas to be represented more than once in a set of x-rays, acting as a diagnostic backup. This reduces the need for retakes without increasing the amount of radiation exposure for the patient.

28. Bite-Wing Film 0: used for posterior teeth in small children
1: used for posterior teeth in children, or positioned vertically to examine anterior teeth in adults
2: used horizontally or vertically to examine posterior teeth in adults
3: shows all posterior teeth on one side of the arch
Currently not recommended because all the contacts cannot be opened on one film
Size #3 film is rarely, if ever, used.
Bitewings are usually taken with a size #2 film and a bite tab or red XCP.

29. Occlusal Film
4: used to examine large areas of the maxilla or mandible
Almost four times the size of standard #2 film

30. Intraoral Film Speed Film speed Iannucci & Howerton (p. 68)
The amount of radiation required to produce a radiograph of standard density
Determined by
The size of silver halide crystals
The thickness of the emulsion
The presence of special radiosensitive dyes
A fast film requires less radiation exposure.
What organization classifies film speed? (The American National Standards Institute [ANSI].)
How does the size of the crystals affect the resolution of the film? (Larger crystals increase film speed, but slightly reduce image resolution.)
Where is the film speed indicated?

31. Intraoral Film Speed The current speeds available are D and F.
E speed film is off the market.
F speed film requires about half the exposure time as D speed film.
To compensate for the graininess of a faster film, Kodak developed the T-grain of silver halide.
Rather than being round, it is flat and oriented, with the flat side facing the tubehead.
F-speed film, the newest and fastest film on the market today, reduces radiation exposure to the patient by 20%-60% compared with E-speed and D-speed film.

32. Extraoral Film Placed outside the mouth during an exposure
Iannucci & Howerton (pp )
Placed outside the mouth during an exposure
Used to examine large areas of teeth and jaws
Panoramic film
Wide view of upper and lower jaws
Cephalometric film
Bony and soft tissue areas in profile (from the side)
What does “extraoral” mean?
Extraoral films are more common in specialty practices, such as orthodontic, pediatric, and oral surgery practices.
Orthodontists commonly use cephalometric films to view the relationship of the jaw to the skull.
Pediatric dentists use panoramic films to see the developing teeth because it is difficult for a child to sit through a full-mouth series of radiographs. It also exposes the child to less radiation than a full-mouth series.

33. Extraoral Film Packaging
Iannucci & Howerton (pp )
Boxed in quantities of 50 or 100 films
Not enclosed in moisture-proof packs
5 x 7 inch or 8 x 10 inch sizes
5 x 12 inch or 6 x 12 inch sizes for panoramic films
Where should extraoral films be stored? (Extraoral films should be stored in a darkroom. This will prevent them from being accidentally opened in a lighted room which can expose and ruin all the film in the box.)
It is advisable to seal an opened box with a rubber band to ensure that the cover doesn’t accidentally fall off and ruin the box of film.

34. Extraoral Film Types Screen film Nonscreen film
Iannucci & Howerton (p. 69) (Fig. 7-18)
Screen film
Nonscreen film
The majority of extraoral films are screen films.

35. Screen Film
Requires the use of a screen in a cassette with phosphors for exposure
The film is sensitive to fluorescent light, rather than direct exposure to x-radiation.
Some screen films are sensitive to blue light and some are sensitive to green light.
The film-screen combinations must match.
These films are also sensitive to white light, as it contains every color of light in the visible spectrum.

36. Nonscreen Film
Nonscreen film does not require the use of a screen; it is exposed directly to x-rays.
It is not recommended for dental use.
The emulsion is sensitive to direct x-ray exposure rather than to fluorescent light.
This type of film does require more exposure time than a screen film and is not recommended for use in dental radiography.

37. Extraoral Film Equipment
Iannucci & Howerton (pp )
Screen films are used with intensifying screens and cassettes.

38. Intensifying Screens
This is a device that transfers x-ray energy into visible light; the visible light then exposes the screen film.
This lowers the radiation dose to the patient.
A screen film is secured in a cassette between two intensifying screens of matching size.
The intensifying screen is a smooth plastic sheet coated with minute fluorescent crystals known as phosphors.
There is a slight loss of image detail as a result of the intensified x-ray beam because the light produces a halo effect at the edge of the image field.
This loss of detail makes panoramic x-rays unsuitable for caries diagnosis. For this reason, pediatric dentists take bite-wings in conjunction with the panoramic x-ray to make a pediatric full set.

39. Intensifying Screens Two types Calcium tungstate screens
Have phosphors that emit blue light
Rare earth screens
Have phosphors that emit green light
These require less radiation than calcium tungstate screens.
Calcium tungstate screens are blue sensitive and rare earth screens are green sensitive.

40. Cassette
Iannucci & Howerton (p. 72)
A cassette is used to hold the film and the intensifying screens.
It may be flexible or rigid.
Most are rigid, except the panoramic cassette, which may be flexible.
Cassette must be light tight and hold the intensifying screen in contact with film; otherwise, the lack of contact between film and cassette will result in a lack of sharpness of the image in that area.

41. Cassette
A rigid cassette has a plastic front cover to allow the photons to pass through.
The back cover is metal to reduce scatter radiation.
The cassette is marked with an L and an R for orientation.
The front of the cassette must always face the patient during exposure.
There is no identification dot on extraoral film.

42. Duplicating Film Different type of film than radiographic film
Iannucci & Howerton (p. 72)
Different type of film than radiographic film
Used to make copies
The longer it is exposed, the lighter the film will be.
This is good for referrals and for the submission of insurance claims.
It has an emulsion on one side only.
It is not exposed to x-rays; it must be used with a film duplicator.
What equipment is needed to duplicate dental radiographs?
The longer the duplicating film is exposed to light, the lighter it becomes. This is the opposite of x-ray film, which becomes darker when exposed to light.

43. Duplicating Film Duplicating film packaging
Available in periapical sizes and 5 x 12 inch and 8 x 10 inch sheets
Boxes of 50, 100, or 150 sheets
How does duplicating film differ from standard intraoral film? (Unlike intraoral film, duplicating film has a single emulsion layer and is never exposed to x-rays- only to light.)

44. Film Storage and Protection
Iannucci & Howerton (pp )
Film is negatively affected by heat, humidity, and radiation.
Film should be kept in a cool, dry place.
Film has an expiration date.
All film must be used before its expiration date.