After completion of this chapter, the student will be able to do the following:
• Define the key terms associated with radiographic examinations
• List the three types of intraoral radiographic examinations
• Describe the purpose and the type of receptor and technique used for each of the three types of intraoral radiographic examinations
• List the various projections that constitute a complete mouth radiographic series (CMRS)
• List the general diagnostic criteria for intraoral radiographs
• List examples of extraoral radiographic examinations
• Discuss the prescribing of dental radiographs
• Describe when prescribing a CMRS for a new patient is warranted
The dental radiographer must have a working knowledge of radiographic techniques. Before the discussion of the basics of the techniques, an understanding of the different types of radiographic examinations is necessary. Dental radiographic examinations may involve either intraoral projections (placed inside the mouth) or extraoral projections (placed outside the mouth).
The purpose of this chapter is to introduce the dental radiographer to the different intraoral radiographic examinations used in dentistry, to define the complete mouth radiographic series, and to describe in detail the diagnostic criteria of intraoral radiographs. In addition, the extraoral radiographic examinations used in dentistry are introduced.
The intraoral radiographic examination is a radiographic inspection of teeth and intraoral adjacent structures. Such intraoral examinations are the foundation of dental radiography. The intraoral radiographic examination requires the use of intraoral image receptors (see Chapter 7). Intraoral receptors are placed inside the mouth to examine the teeth and supporting structures.
The following three common types of examinations use intraoral radiographs:
Each of these examinations has a certain purpose and requires the use of a specific type of imaging receptor and technique.
Purpose: Periapical examination is used to examine the entire tooth (crown and root) and supporting bone.
Type of Imaging Receptor: The periapical receptor is used in periapical examination. The term periapical is derived from the Greek prefix peri- (meaning “around”) and the Latin word apex (referring to the terminal end of a tooth root). Periapical images show the terminal end of the tooth root and surrounding bone as well as the crown.
Technique: Two methods are used for obtaining periapical radiographs: (1) the paralleling technique (see Chapter 17) and (2) the bisecting technique (see Chapter 18).
Purpose: Interproximal examination is used to examine the crowns of both maxillary and mandibular teeth on a single image. As the term proximal suggests, this examination is useful in examining adjacent tooth surfaces and crestal bone.
Type of Imaging Receptor: The bite-wing receptor is used in interproximal examination. The bite-wing receptor has a “wing” or tab attached to it; the patient “bites” on the wing to stabilize the receptor.
Technique: The bite-wing technique (see Chapter 19) is used in interproximal examination.
Purpose: Occlusal examination is used to examine large areas of the maxilla or the mandible on one image.
Type of Imaging Receptor: The occlusal receptor is used in occlusal examination. As the term occlusal suggests, the patient “occludes,” or bites on, the entire receptor.
Technique: The occlusal technique (see Chapter 21) is used in occlusal examination.
The complete mouth radiographic series (CMRS) is also known as the full mouth series (FMS or FMX) or the complete series. The CMRS can be defined as a series of intraoral dental radiographs that show all the tooth-bearing areas of both jaws. Tooth-bearing areas are the regions of the maxilla and the mandible, where the 32 teeth of the human dentition are normally located. Tooth-bearing areas include dentulous areas, or areas that exhibit teeth, as well as edentulous areas, or areas where teeth are no longer present.
The CMRS consists of periapical radiographs alone or a combination of periapical and bite-wing radiographs. Bite-wing radiographs are used only in areas where teeth have interproximal contact with other teeth to examine the contact areas for caries (decay). To include every tooth and all tooth-bearing areas, a range of 14 to 20 images may be included in the CMRS.
The number of images is dictated by the radiographic technique used for exposure and the number of teeth present. For example, in the patient without teeth, 14 periapical images are usually sufficient to cover the edentulous arches. In the dentulous patient, the number of periapical images varies, depending on which technique—paralleling or bisecting—is used. Receptor size is also dictated by the technique used.
A diagnostic radiograph, as described in Chapter 8, provides a great deal of information. Specific diagnostic criteria for each radiographic exposure are described in Chapters 17, 18, 19, and 21 (paralleling, bisecting, bite-wing, and occlusal, respectively). General diagnostic criteria for intraoral radiographs are listed in Box 16-1.
The extraoral radiographic examination is a radiographic inspection of large areas of the skull or jaws. The extraoral radiographic examination requires the use of extraoral imaging receptors (see Chapter 7). Extraoral receptors are placed outside the mouth. Examples of common extraoral radiographs include the panoramic radiograph as well as the lateral jaw, lateral cephalometric, posteroanterior, Waters, submentovertex, reverse Towne, transcranial, and tomographic projections. Each of these extraoral examinations has a specific purpose and requires the use of certain receptors and techniques. The purposes, receptors, and techniques used in extraoral radiography are described in Chapters 22 and 23 .
As discussed in Chapter 5, the prescription of dental radiographs is based on the individual needs of the patient. The dentist uses professional judgment to make decisions about the number, type, and frequency of dental radiographs. Every patient’s dental condition is different, and therefore every patient must be evaluated for dental radiographs on an individual basis.
For example, not all patients need a CMRS. As detailed in the Guidelines for Prescribing Dental Radiographs (see Table 5-1), a CMRS is appropriate when a new adult patient presents with clinical evidence of generalized dental disease or a history of extensive dental treatment. Otherwise, a combination of bite-wings, selected periapicals, and/or a panoramic radiograph should be prescribed on the basis of a patient’s individual needs.
• Dental radiographic examinations may involve either intraoral projections (placed inside the mouth) or extraoral projections (placed outside the mouth).
• The intraoral radiographic examination is a radiographic inspection of teeth and intraoral structures. The three common types of intraoral examinations are periapical, interproximal, and occlusal examinations.
• Periapical examination is used to inspect the crowns and roots of teeth as well as the supporting bone. Periapical receptors are used in periapical examination. Either the paralleling technique or the bisecting technique can be used to expose periapical receptors.
• Interproximal examination is used to examine the crowns of maxillary as well as mandibular teeth on a single image. The bite-wing receptor and the bite-wing technique are used in interproximal examination.
• Occlusal examination is used to examine large areas of the maxilla or mandible on one image. Occlusal receptors and the occlusal technique are used.
• The complete mouth radiographic series (CMRS), or full-mouth series (FMS or FMX), is an intraoral series of dental radiographs that shows all the tooth-bearing areas of the maxilla and the mandible and consists of 14 to 20 images (periapical radiographs alone or combination of periapical and bite-wing radiographs), depending on radiographic technique and number of teeth present.
• An intraoral radiograph is considered diagnostic if it shows images with optimal density, contrast, definition and detail, and minimal distortion. In addition, a diagnostic periapical radiograph shows the entire crowns and roots of the teeth being examined, and a diagnostic bite-wing radiograph should show open contacts.
• The extraoral radiographic examination is a radiographic inspection of large areas of the skull or jaws.
Johnson, ON, Thomson, EM, Intraoral radiographic procedures. Essentials of dental radiography for dental assistants and hygienists, ed 8, Upper Saddle River, NJ, Pearson, 2007.
Miles, DA, Van Dis, ML, Jensen, CW, Ferretti, A, Intraoral radiographic technique. Radiographic imaging for the dental team, ed 4, St. Louis, Saunders, 2009.
White, SC, Pharoah, MJ, Intraoral radiographic examinations. Oral radiology: principles and interpretation, ed 6, St. Louis, Mosby, 2009.
For questions 1 to 10, match each definition with one term.
________ 1. A receptor placed inside the mouth
________ 4. To close or to bite
________ 5. A receptor used to examine a large area of the maxilla or mandible in one image
________ 6. A receptor used to examine the crowns of the maxillary and mandibular teeth on a single image
________ 7. A receptor placed outside the mouth
________ 10. A receptor used to examine the entire tooth and supporting bone
11. List the three types of intraoral radiographic examinations.
12. Describe the purpose, type of receptor, and technique used for each of the three types of intraoral radiographic examinations.
13. List the general diagnostic criteria for intraoral radiographs.