Dental radiography can be performed using various techniques.
Dental radiography involves producing X-ray images of teeth and oral structures to detect disease, according to "Dental Radiography: Principles and Techniques." Dental assistants--who can complete one-year diploma or two-year associate degree programs--must be certified to take X-rays in some states. Dental hygienists, who can complete associate degree or four-year bachelor's degree programs in this field, must be licensed in all states to practice dental hygiene and take dental radiographs, according to the U.S. Bureau of Labor Statistics. These professionals must master various techniques to be successful in this field.
Methods
Dental radiography can be performed using either traditional film or digital devices. When working with traditional film, intraoral dental X-ray machines are used for those films placed inside the mouth, while extraoral machines are used for films placed outside the mouth. Dental radiographers can use a film holder to hold an intraoral film inside the mouth. They also can use a beam alignment device to help position the intraoral X-ray machine's cone, also called the position-indicating device, in relation to the tooth and film.
When using traditional film, X-rays interact with a layer on the film called the film emulsion, which contains silver halide crystals that absorb the radiation. The crystals produce a latent image of a tooth and its surrounding structures, which becomes a visible image once the film is chemically processed. On the other hand, digital radiography involves the use of an intraoral sensor instead of a film to capture an image of a tooth. Once X-rays hit the sensor, the electronic charge produced on the sensor is converted into digital form, and the image then is visible on a computer. When performing digital radiography, dental radiographers can still use a traditional intraoral dental X-ray machine.
Film Types
Three types of intraoral film exist--periapical, bite-wing and occlusal. The periapical film is used to view an entire tooth--including the tooth's root and crown--as well as the bone that supports the tooth. Meanwhile, the bite-wing film is used to view the crowns of both the upper and lower teeth on one film. This type of film is especially important for detecting cavities or other conditions between teeth. An occlusal film is used to examine large areas of the upper or lower jaw.
A panoramic film, which is a type of extraoral film, provides a wide view of the upper and lower jaws on one film. A cephalometric film, another type of extraoral film, is used to examine the bony and soft tissues of the face.
Techniques
Dental radiographers can expose films to X-rays using two techniques--the paralleling technique and the bisecting technique. The paralleling technique involves placing an intraoral film in the mouth parallel to the long axis of the tooth--the imaginary line that divides a tooth into two equal halves lengthwise. The central ray of an X-ray beam then is directed perpendicular to the film and long axis of the tooth.
On the other hand, the bisecting technique involves placing a film along the tongue-side surface of a tooth and visualizing the angle formed by the plane of the film and of the tooth. The dental radiographer then must visualize the line that divides this angle in half. She then must direct the central ray of an X-ray beam perpendicular to this line to successfully capture the image of the tooth.
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