1. Film Processing

2. Dental X-Ray Film
Film used in dental radiography is similar to photographic film, with some adaptations.
A photographic image is produced on dental x-ray film when it is exposed to x-rays that have passed through teeth and adjacent tissues.
The dental assistant must understand the composition of x-ray film and latent image formation that results in film exposure to x-rays.
How does a skilled dental assistant reduce the patient’s exposure to x-rays? (By reducing the number of retakes.) 2 2

3. Film Composition
Intraoral dental film is made up of a clear, semi-flexible, cellulose acetate film base that is coated on both sides with an emulsion of silver bromide, silver halide, and silver iodide that is sensitive to radiation.
Why is the film base a necessary component of the film composition? (The chemical crystals are embedded in the film base.) 3 3

4. Dental X-Ray Film Processing
Processing is a series of steps that changes the latent image on the exposed film into a radiograph by producing a visible image on the film.
Proper processing is just as important as exposure technique in producing diagnostic-quality radiographs.
Radiographs that are non-diagnostic because of poor processing techniques must be retaken, exposing the patient to unnecessary radiation.
In many practices intraoral films are processed in an automatic processor; however, it is still necessary to know how to process the film manually.
Why is it necessary to know how to process the film manually in practices that have automatic processors? (Two reasons: [1] to be able to identify and correct errors in processing and [2] to have the ability to develop a film more quickly, as with endodontics. A film can be developed manually in about 2 minutes.) 4 4

5. The Five Steps in Processing Dental Radiographs
Developing
Rinsing
Fixation
Washing
Drying
Which step consumes the most time? (Drying.) 5
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6. Developing Developing is the first step in processing films.
The purpose of the developer is to chemically reduce the exposed silver halide crystals to black metallic silver.
The developer solution also softens the film emulsion during this process.
Composition of the Developer:
Developing agents/reducing agents: Hydroquinone & Elon
Reduces exposed silver halide crystals chemically into black metallic silver
Hydroquinone: slowly generates the black tones & contrast
Elon: quickly generates the gray tones in the image
Preservative: Sodium sulfite
Prevents rapid oxidation of the developing agents
Activator: Sodium carbonate
Activates developing agents by providing required alkalinity
Restrainer: Potassium bromide
Prevents the developer from acting on the unexposed silver halide crystals, which produce film fog
In manual processing for endodontic procedures, the film is typically placed in the developer just long enough for an image to appear. This usually takes less than a minute. However, initial and final films should never be developed in this way. 6 6

7. Rinsing
Rinsing of the films is necessary to remove the developer from the film so that the development process stops.
Usually, agitating the film rack for 20 seconds is sufficient.
This must be done under safelight conditions.
When rinsing, unexposed crystals still remain on the film. Therefore, rinsing needs to be done under a safelight, since white light will expose those crystals and distort the image. 7
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8. Fixing
The acidic fixing solution removes the unexposed silver halide crystals from the film emulsion and hardens the film emulsion
For permanent fixation, the film is kept in the fixer for a minimum of 10 minutes.
However, films may be removed from the fixing solution after 3 minutes for viewing.
Films that are not properly fixed will fade and turn brown in a short time.
Leaving films in the fixer for a long time (e.g., over a weekend) can remove the image from the film leaving a clear film.
A working film for endodontic procedures can be placed in the fixer for roughly 1 minute and will last long enough for the dentist to get the information he or she needs. 8
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9. Composition of the Fixer
Fixing agent: Ammonium thiosulfate/ sodium thiosulfate
Removes the unexposed and any remaining undeveloped silver halide crystals
Preservative: Sodium sulfite
Slows the rate of oxidation and prevents deterioration of the fixing agent
Hardening agent: Potassium alum
Shrinks and hardens the gelatin emulsion
Acidifier: Acetic acid/ sulfuric acid
Stops further development by neutralizing the alkali of the developer

10. Washing After fixation, a water bath is used to wash the film.
The washing step requires about 20 minutes to thoroughly remove all excess chemicals from the emulsion.
This step no longer needs to be done in safelight. Why? (Because the unexposed crystals have been removed, there is nothing to react with the white light.) 10
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11. Drying The final step in film processing is the drying of the films.
Films may be air-dried at room temperature in a dust-free area or placed in a heated drying cabinet.
Films must be completely dried before they can be handled for mounting and viewing.
Automatic processors use warm air to dry films more quickly. 11
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12. Film-Processing Solutions
Film-processing solutions are available in the following forms:
Ready-to-use liquid
Liquid concentrate must be mixed with distilled water
Powder must be mixed with distilled water
Ready-to-use liquid is by far the most commonly used solution.
Powder and concentrate require mixing that most practices choose not to take the time to do. 12
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13. The Darkroom
The room must be light tight and no white light should be used until the film has been placed in the fixer for several minutes
Any leakage of white light can cause film fog. A fogged film appears dull gray, lacks contrast, and is non-diagnostic.
What might cause a fogged film besides light leaks in the darkroom? (The film may have been left in the x-ray room after the initial exposure and exposed to background radiation. Keep exposed films outside the radiography operatory.) 13
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14. Types of Darkroom Lighting
Unwrapped films that are left too close to the safelight or exposed to the safelight for more than 2 to 3 minutes appear fogged.
A safelight must be placed a minimum of 4 feet away from the film and working area.
The voltage of the light is 7 ½ to 15 watts with special filter.
Some safelights are made only for intraoral films, some for only extraoral films, and still others for both intraoral and extraoral films. 14
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15. The Processing Tank
Manual processing is a method that is used to develop, rinse, fix, and wash dental x-ray films.
The essential piece of equipment required for manual processing is a processing tank.
The processing tank is divided into compartments to hold the developer solution, water bath, and fixer solution.
A processing tank has two insert tanks and one master tank.
What controls the temperatures of the developer and fixer solutions?
What is the optimum temperature for the water bath in the insert tank? 15 15

16. Processing Tanks
What’s the purpose of the cover? (To keep solutions from evaporating when not in use.)
How often should solutions be changed? (Every 3 to 4 weeks.) 16
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17. Manual Processing Accessories
Stirring rods or paddles
Used to agitate developer and fixer before processing
Film Hangers
Clips used to hold films during processing
Timer
Used to track time period in each solution and when films need to be moved along the process
Thermometer
Non-mercury type
Placed in the developer tank because development time is based on temperature of solution

18. Time and Temperature Chart
Solution temperature
Time in developer
Rinse time
Time in fixer
Wash time
65 °
6 minutes
30 seconds
10-12 minutes
20 minutes
68°
5 minutes
10 minutes
70°
4.5 minutes
9-10 minutes
72°
4 minutes
8-9 minutes
75°
3 minutes
6-7 minutes
80°
2.5 minutes
5-6 minutes

19. The Automatic Processor
Automatic film processing is a fast and simple method used to process dental x-ray films.
Other than opening the film packet, all steps of film processing are handled by the automatic processor.
Automatic film processing requires only 4 to 6 minutes for the development, fixing, washing, and drying of a film, whereas manual processing techniques require approximately 1 hour.
Never open the automatic processor with the overhead light on if there is still film being processed.
Should a film get stuck, open the automatic processor with the safelight on and try to locate the film. If necessary, reprocess the film or develop it manually. 19 19

20. The Automatic Processor
The automatic processor maintains the correct temperature of the solutions and adjusts the processing time.
Proper maintenance of the automatic processor reduces the chance of errors during film processing.
Many dental offices that have automatic processors still maintain manual processing equipment as a standby if the automatic processor malfunctions.
Manual processing is commonly used to quickly develop working endodontic films. 20
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21. Fig. 39-29 A, An automatic film processor
Fig A, An automatic film processor. B, An automatic film processor equipped with a daylight film loader. A B
The automatic processor pictured in part B displays a day loader, a device used to unwrap and process films without the need for a darkroom. 21
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22. Advantages and Disadvantages of Automatic Film Processing
Less processing time is required.
Time and temperature are automatically controlled.
Less equipment is used.
Less space is required.
Disadvantages:
Require diligent maintenance
Cleaning of rollers and solution checks often
There is also less chance of errors during automatic film processing. 22
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23. Processing Errors
Processing errors may occur for a variety of reasons, including:
Time and temperature errors
Chemical-contamination errors
Film handling errors
Lighting errors
The dental assistant must be able to recognize the appearance of common processing errors and know what to do to prevent such problems from occurring again.
For films to be of diagnostic use, they must be error-free. 23
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24. Examples of Common Processing Errors
The following photographs illustrate common examples of technical errors that can occur during film processing.
Such errors result in radiographs that are not diagnostic, thus requiring retakes and additional exposure to the patient. 24
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25. Fig. 39-31 A, Overdevelopment
Fig A, Overdevelopment. (From Iannucci JM, Jansen Howerton L: Dental radiography: principles and techniques, ed 4, St Louis, 2012, Saunders.)
What can cause overdeveloped film? (Overdevelopment results from a developer solution that is too concentrated or too warm, or film that is left in the developer solution for too long.) 25
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26. Fig. 39-31 B, Developer splash
Fig B, Developer splash. (From Iannucci JM, Jansen Howerton L: Dental radiography: principles and techniques, ed 4, St Louis, 2012, Saunders.)
A neat work area can prevent errors such as developer splash.
Give another example of an error caused by chemical contamination. 26
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27. Fig C, Scratched film. (From Iannucci JM, Jansen Howerton L: Dental radiography: principles and techniques, ed 4, St Louis, 2012, Saunders.)
Developer softens the emulsion, leaving it susceptible to scratches.
Careful handling, especially before fixing, will prevent scratched film. 27
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28. Fig D, Water spots. (From Iannucci JM, Jansen Howerton L: Dental radiography: principles and techniques, ed 4, St Louis, 2012, Saunders.)
How can this type of radiograph-processing error be avoided? 28
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29. Fig E, Solution too low. (From Iannucci JM, Jansen Howerton L: Dental radiography: principles and techniques, ed 4, St Louis, 2012, Saunders.)
How can this error be prevented? 29
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30. Fig F, Roller marks. (From Iannucci JM, Jansen Howerton L: Dental radiography: principles and techniques, ed 4, St Louis, 2012, Saunders.)
What can the dental assistant do to prevent this type of error? 30
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31. Fig G, Fingerprints. (From Iannucci JM, Jansen Howerton L: Dental radiography: principles and techniques, ed 4, St Louis, 2012, Saunders.)
Handle films by its edges until processing is complete. 31
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32. Fig. 39-31 H, Overlapped films
Fig H, Overlapped films. (From Iannucci JM, Jansen Howerton L: Dental radiography: principles and techniques, ed 4, St Louis, 2012, Saunders.)
This film-handling error is caused when two films come into contact during processing.
It can be prevented by separating the films. 32
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33. Fig I, Underdeveloped. (From Iannucci JM, Jansen Howerton L: Dental radiography: principles and techniques, ed 4, St Louis, 2012, Saunders.)
Underdeveloped film is the exact opposite of overdeveloped film.
What are some of the causes of underdevelopment? 33
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34. Fig J, Reticulation. (From Iannucci JM, Jansen Howerton L: Dental radiography: principles and techniques, ed 4, St Louis, 2012, Saunders.)
This type of error is rare.
Reticulation is caused by a sudden temperature change between solutions. 34
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35. Fig K, Fixer Spots. (From Iannucci JM, Jansen Howerton L: Dental radiography: principles and techniques, ed 4, St Louis, 2012, Saunders.)
A clean work area in the darkroom will help prevent fixer from coming into contact with the film before processing. 35
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36. Fig. 39-31 L, Developer cutoff
Fig L, Developer cutoff. (From Iannucci JM, Jansen Howerton L: Dental radiography: principles and techniques, ed 4, St Louis, 2012, Saunders.)
The straight white border represents the undeveloped part of the film, which results from an insufficient level of developer. 36
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37. Fig M, Number of errors. (From Iannucci JM, Jansen Howerton L: Dental radiography: principles and techniques, ed 4, St Louis, 2012, Saunders.)
Identify the errors represented here. 37
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38. Fig N, Fixer cutoff. (From Iannucci JM, Jansen Howerton L: Dental radiography: principles and techniques, ed 4, St Louis, 2012, Saunders.)
The straight black border represents the unfixed part of the film, which is the result of an insufficient level of fixer. 38
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39. Fig O, Air bubbles. (From Iannucci JM, Jansen Howerton L: Dental radiography: principles and techniques, ed 4, St Louis, 2012, Saunders.)
What can be done to prevent air bubbles from forming? 39
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40. Fig. 39-31 P, Black fingerprint
Fig P, Black fingerprint. (From Iannucci JM, Jansen Howerton L: Dental radiography: principles and techniques, ed 4, St Louis, 2012, Saunders.)
This film-handling error is caused when the film is touched with fingers contaminated with fluoride or developer.
The solution is to wash and dry films thoroughly before processing. Also, only handle film by its edges until processing is complete. 40
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41. Fig. 39-31 Q, Static electricity
Fig Q, Static electricity. (From Iannucci JM, Jansen Howerton L: Dental radiography: principles and techniques, ed 4, St Louis, 2012, Saunders.)
Open film packets slowly to prevent damage to the film caused by static electricity. 41
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42. Fig. 39-31 R, Exposure to light
Fig R, Exposure to light. (From Iannucci JM, Jansen Howerton L: Dental radiography: principles and techniques, ed 4, St Louis, 2012, Saunders.)
What might the dental assistant check for to avoid this processing error? 42
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43. Fig S, Fogged film. (From Iannucci JM, Jansen Howerton L: Dental radiography: principles and techniques, ed 4, St Louis, 2012, Saunders.)
Name one error that could cause fogged film. (Storing film where it can be exposed to radiation.)
What might the dental assistant check for to avoid this processing error? (See Table 39-7, Lighting Errors and Solutions, on p. 599 of the textbook.) 43
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