Mesial mandibular premolar teeth
As stated previously, most mandibular teeth can be imaged by using the parallel technique.7 But in some patients there is a problem with imaging the apices of the mesial premolars.3,8 Typically, this is the third premolar (especially the mesial root) in cats and the first and second premolars in dogs. The
challenge with imaging these teeth is to avoid interference of the mandibular symphysis. A standard parallel view will not
image these apices.
To image the entire arcade, it is often necessary to use the bisecting angle technique.7 This technique can be used to image the entire arcade or just the mesial premolars, with a second film using the standard
parallel technique (which is more accurate) for the molars and distal premolars.
Position the film in the patient's mouth at about a 90-degree angle to the tooth roots so that the lingual edge of the film
is touching the opposite mandible. Then place the beam perpendicular to the angle between the tooth roots and the film, which
is about 45 degrees (Figures 16A-16C). Note that resultant image may suffer from slight elongation, which is considered a fair tradeoff for viewing the apices.
DEVELOPING DENTAL RADIOGRAPHS
Dental radiographs can be developed by using hand developing, automatic dental film processors, or standard radiograph processors.
For instructions on automatic dental processing, refer to the operating manual for that piece of equipment. Using standard
radiograph automatic processors for developing dental films is not recommended because of improper development and fixation
as well as a chance of losing the film within the processor.
Regardless of the method chosen, the first step in developing dental radiographs is to remove the film from the packet. This
must be done in a light-safe area to avoid exposing the film to light, which will destroy the image. To do this, carefully
open the package by grasping the tag. There are three internal components: the film, a piece of black paper, and a lead sheet
(Figure 17).6 The paper may either be in front of the film (toward the tube head) or wrapped around the film entirely. The lead sheet is
behind the film. All three components feel different. Remove these contents and separate the film from the other pieces. Grasp
the film only by the corner to avoid fingerprint artifacts.13 For hand development, place the film clip on the edge of the film before separation to avoid touching the film.
Developing the film with chemicals manually, without the use of an automatic processor, is the least expensive and most common
method of developing dental radiographs.5,6,14,15 This method is similar to the dip tank developing that was used historically for standard films.
Hand developing can be performed in a darkroom by using household cups or bowls or in the operatory room with a chair-side
developer. A chair-side developer unit has cups containing the chemicals for developing and fixing the film, which are visualized
through a tinted filter (Figure 18). The advantages of chair-side developing include time efficiency and the allowance for continual patient monitoring by the
technician during the development process.6,14,15
Hand developing methods use one of two different techniques to produce an image on the film. These methods are called time-temperature and sight developing.14 Both methods use a two-step rapid development solution.*** It is important to note that standard radiograph solutions are
a poor substitute for dental film solutions since the time of development will be greatly increased and the quality of development
and fixation will be inferior with standard solutions.14
Time-temperature development. With this method, continuously monitoring the temperature of the developing solution determines the required development time
according to the manufacturer's recommendation.14 This method is the most scientifically correct but can be cumbersome.6
Sight development. This method is performed by dipping the film in the developer for a short time, removing it, and then critically examining
it with the safe light or through the filter.6,14 This process is repeated until the first hint of an image appears, indicating the film is properly developed. Sight development
has two distinct advantages over the time-temperature technique. First, continuous temperature monitoring is not necessary.
However, the solution temperature rises during the day, especially if numerous films are being developed, which shortens development
time. So unless frequent temperature readings are performed, this can result in overdeveloped films. Second and more important,
the sight development method allows an experienced technician to adjust for minor technique errors by relatively overdeveloping
or underdeveloping the film.14 This adjustment will not compensate for major errors but will avoid some retakes.