Chapter 29 Extraoral Radiography and Alternate Imaging Modalities.

Chapter 29

Extraoral Radiography and Alternate Imaging Modalities

Copyright ©2012 by Pearson Education, Inc.All rights reserved.

Essentials of Dental Radiography for Dental Assistants and Hygienists, Ninth EditionEvelyn M. Thomson • Orlen N. Johnson

ObjectivesDefine the key words.Describe the purpose and use of extraoral

radiographs.List seven extraoral radiographs that

contribute to the treatment of dental patients.

Explain the need for proper extraoral film handling.



ObjectivesExplain the role intensifying screens play in

producing a radiographic image.Match blue- and green-light sensitive film

with the appropriate intensifying screen.Explain the role of the extraoral film

cassette.Describe how extraoral radiographs are

labeled.



Objectives

Explain the need for proper care and cleaning of cassettes and intensifying screens.

Explain the role grids play in extraoral radiography.

Explain tomography and describe its role in oral health care.

Explain cone beam computed tomography and describe its role in oral health care.



Introduction Extraoral radiographs and alternate

imaging modalities such as computed tomography record large areas of the dental arches, supporting facial structures, and skull using image receptors that are positioned outside the mouth.



Introduction Knowing the types of extraoral radiographs

and alternate imaging modalities, understanding the conditions that most likely benefit from each; and being able to recognize the different images are valuable skills.



Introduction The dental assistant and/or hygienist may

be asked to educate the patient about the procedure or assist with scheduling the patient’s appointment for the referral.

Oral radiographers should be able to communicate professionally with other health care professionals.



Figure 29-1 A combination panoramic and cephalometric dental x-ray unit. (Courtesy of Planmeca.)



Purpose and Use of Extraoral Imaging Modalities Examine large areas of the dental arches

and skull.Study growth and development of bone

and teeth.Detect fractures and evaluate trauma.Detect pathological lesions and diseases of

the jaws.Detect and evaluate impacted teeth.



Purpose and Use of Extraoral Imaging Modalities

Evaluate temporomandibular disorder (TMD). Plan treatment for dental implants and

prosthetic appliances.



Figure 29-2 Cephalometric radiograph produced with a filter placed between the tube and patient to remove some of the x-rays to record outlines of the soft tissue profile.



TABLE 29-1 Extraoral Radiographs of the Maxillofacial Region



TABLE 29-1 (continued) Extraoral Radiographs of the Maxillofacial Region



Extraoral Image ReceptorsTraditional filmIntensifying screensCassettesFilm identificationCare of cassettes and intensifying screens



Figure 29-3 Loading film into a flexible cassette under safelight conditions.



PROCEDURE 29-1Loading an extraoral cassette



Figure 29-4 Loading a rigid cassette.



Figure 29-5 Film is placed between the intensifying screens.



Figure 29-6 Static electricity artifacts. Blank area on a panoramic film showing static electricity artifacts.



Figure 29-7 Cross-section of cassette showing the effect of x-ray and fluorescent light on the film. X-ray A strikes a crystal in the screen behind the film, producing light that then forms latent images in the silver halide crystal of the film. X-ray B strikes a silver halide crystal in the film, forming a latent image. X-ray C strikes a crystal in the screen in front of the film, producing light, which then forms latent images in the silver halide crystals of the film.



Figure 29-8 The back side of three rigid cassettes of various sizes.



Figure 29-9 Film identification printer for imprinting permanent identification information on the radiographic image.



Figure 29-10 Grid used to absorb back scattered radiation is placed between the patient and the film to absorb scattered x-rays to reduce film fog.



Figure 29-11 Serial radiographs produced by tomography of the temporomandibular joint showing the head of the condyle in the glenoid fossa with the mouth closed, in the at-rest position, and with the mouth open.(Courtesy of McCormack Dental X-ray Laboratory.)



Figure 29-12 A combination panoramic and TMJ tomography imaging dental x-ray unit. (Courtesy of Planmeca.)



Figure 29-13 CT scanner.



Figure 29-14 Cone beam volumetric imaging machine. Designed for the oral health care practice, can also produce panoramic radiographs.(Courtesy of Gendex Dental Systems/Imaging Sciences Intl.)



Figure 29-15 Image produced by CBCT and reconstructed software. Note the images produced from different planes and the reconstructed 3D image of the teeth in the arches.(Courtesy of Planmeca.)



Review: Chapter SummaryExtraoral radiographs image large areas of

the head and facial regions.Extraoral screen film is used with a pair of

intensifying screens housed in a light-tight cassette.

Grids are devices used to absorb scatter radiation that would fog the film and compromise image contrast.



Review: Chapter SummaryRadiographs are produced with a stationary

x-ray source an image receptor.The practitioner must be skilled in

interpreting images obtained by CBCT.



Recall: Study QuestionsGeneralChapter Review



Reflect: Case StudyConsider the following patients and conditions.

Which of the six extraoral radiographs described in this chapter might be the best recommendation for these cases?



Reflect: Case Study(Note: Radiographs of the skull are difficult

to interpret due to the numerous structures that exist in a very small area. These structures often appear superimposed over each other, requiring multiple views to obtain a good diagnosis. Therefore, in some of these cases, while there is usually a best answer, there may be more than one correct answer.)



Reflect: Case Study1. A 20-year-old patient presents with pain

and swelling from an impacted third molar. The patient can open only 10 mm. No panoramic unit is available. What is an alternate extraoral projection type that can be used to assess with diagnosis for this patient?



Reflect: Case Study2. A 13-year-old patient presents for an

orthodontic consultation. Occlusal (teeth) and facial disharmonies (soft tissue relationships) need to be assessed prior to treatment intervention.



Reflect: Case Study3. A difficult extraction case presents with a

severely decayed maxillary molar. During the extraction procedure, the root tip fractures and is possibly lost in the sinus cavity.

4. A medically compromised patient suffered a seizure and fell. A fractured mandibular condyle is suspected.



Reflect: Case Study5. A 69-year-old patient presents with a

history of degenerative joint disease that may be affecting the temporal mandibular joint. An examination for the purpose of diagnosing ankylosis (a stiffening of the TMJ) is planned.



Reflect: Case Study6. A patient presents for extraction of

several badly decayed teeth, following which the prosthodontist will construct a maxillary full denture and a mandibular partial denture.



Relate: Laboratory ApplicationProceed to Chapter 29, Laboratory

Application, to complete this activity.

Chapter 29 Extraoral Radiography and Alternate Imaging Modalities.

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Transcript of Chapter 29 Extraoral Radiography and Alternate Imaging Modalities.