23220 Principles of Radiographic InterpretationEDUCATIONAL OBJECTIVESUpon completing this chapter, the student will be able to:1. Dene the key terms listed at the beginning of the chapter.2. Understand the steps to be taken in interpreting radiographs and their importance in establishing a diagnosis, as well as discuss how the patient’s signs and symptoms relate to the radiographic diagnosis.3. List the questions that the dental professional should ask and be able to answer prior to the radiographic procedure, as well as list the questions that the dental professional should ask after the preliminary radiographic examination is performed.KEY TERMSbenign lesionbilateral lesiondiagnosisdenitive diagnosisdierential diagnosisinterpretationmalignant growthunilateral lesionvitality testingprovides the signs or symptoms on which to build a diagno-sis. Other signs or symptoms that may be part of a diagnosis are gathered by using the patient’s chief complaint, dental and medical history, clinical examination, vitality testing, advanced imaging, biopsy, and laboratory tests. e steps that are to be taken in formulating a denitive diagnosis are: (1) identication of an area or structure that is questionable, (2) interpretation of what has been identied (dierential diagnosis), and (3) diagnosis based on the interpretation (denitive diagnosis). Because the role of supportive dental professionals is included in steps 1 and 2, they need to develop interpretive skills to identify all normal anatomic structures, both tooth and bone, and artifacts that may be visible on intraoral, panoramic, and other extraoral radiographs. e dental professional also must be able to dierentiate deviations in radiographic form and density from normal structures.To produce adequate diagnostic lms, the dental pro-fessional must know what relevant information is being sought from the radiograph. is base of knowledge makes exposing the radiographs a more challenging, interesting, and rewarding process. If dental professionals know how periapical pathologic conditions appear radiographically, they also will understand the necessity of seeing the entire periapical area of the tooth in question to make a proper diagnosis. For example, if dental professionals know how Introductione inclusion of the following ve chapters on interpreta-tion in this text is not meant to imply that it is the dental professional’s role to make the nal radiographic diagnosis but rather to stress that interpretation is only one step in preparing a diagnosis on a patient. is step should be shared by all of the dental clinicians. At present, the nal diagnostic role legally rests with the dentist, but certainly help and input from other members of the dental team should be encouraged. e purpose of Chapters 19 through 24 is to give dental professionals some basic understanding of radiographic interpretation, to stimulate interest, and to demonstrate the importance of producing an adequate diagnostic radiograph.is chapter discusses the main dierences between interpreting radiographs and ultimately formulating a denitive diagnosis. e diagnostic questions that the dental professional should ask in devising a dierential diagnosis are included in this chapter as well.Dierential Diagnosise dictionary denes interpretation as “an explanation” and diagnosis as “the art or act of identifying a disease from its signs and symptoms.” e interpretation of radiographs 233CHAPTER 20 Principles of Radiographic Interpretationdicult—and, in some cases, how impossible—it is to interpret caries on radiographs with horizontal overlapping of the teeth, they will be motivated to prevent or correct this error in technique to produce adequate diagnostic images.Diagnostic Questionsere are certain radiographic questions that diagnosticians should ask themselves and be able to answer to help make a proper dierential diagnosis. Further analysis of the dif-ferential diagnosis will lead to the denitive diagnosis. e list that follows contains questions to gather recommended clinical and radiographic information with which diagnosti-cians should be familiar.Preliminary Questions• Whatisthepatient’schiefcomplaint?Often,thisgivesimportant information that helps focus the diagnosis.• Whatweretheclinicalndingsthatpromptedthedentalprofessionaltorequesttheradiographs?• What radiographic projections are available, and whatadditional images should be ordered? e dental pro-fessional should start with the basic intraoral images, andthenprogressifnecessarytoanocclusalprojection,extraoral radiograph, panoramic view (Fig. 20.1), and nally a cone beam computed tomography (CBCT) scan or, in some cases, a magnetic resonance image (MRI).• Have periapical and bitewing radiographs been takenrecently?Previousimagesmaygiveahistoryoftreatment(e.g., signs of pulp capping bring periapical pathologic process to the forefront of the diagnostic possibilities; Fig. 20.2).Questions That Follow the Preliminary Radiographic Examination• Isaboneorsofttissuepathologysuspected?• What does the vitality test reveal? About 70% of allpathologicconditionsseeninthejawsaretheresultofnonvital teeth and their sequela.• Figure 20.1 Panoramic radiograph with third molar impaction. • Figure 20.2 Pulp capping. • Figure 20.3 Radiopaque (RO) lesion. • Isthelesionradiolucent(RL),radiopaque(RO),ormixed (bothRLandROcomponents;Figs.20.3to20.5)?• Couldthesuspected“lesion”beananatomiclandmark(Fig. 20.6)? Landmarks are located in specic areasthroughout the oral cavity and are well within normal limits.• Whereis the lesionlocated? Is itin themandible, themaxilla,orelsewhere?Certainlesionsareseen moreinone jaw than the other or can usually occur in onelocation(e.g.,anasopalatinecyst;Fig.20.7).• Isthelesionaunilateral or bilateral lesion(Fig.20.8)?Most (but not all) bilateral ndings are normal anatomic landmarks.HELPFUL HINTWhen distinguishing between whether a radiographic nding is an anatomic landmark or a suspicious lesion, it is important to know the radiographic appearance (radiopaque [RO] or radiolucent [RL]) of the anatomic landmarks and their respective locations. 234 CHAPTER 20 Principles of Radiographic Interpretation• Figure 20.5 Radiolucent (RL) lesion. • Figure 20.6 Normal anatomy. • Figure 20.7 Nasopalatine cyst. • Figure 20.8 Bilateral lesion. • Figure 20.4 Mixed lesion. 235CHAPTER 20 Principles of Radiographic Interpretation• What isthe sizeand shape of the lesion(expressed inmillimeters)?• Are the borders of the lesionwell dened (Fig.20.9)?Well-dened lesions are the signs of a benign lesion, whereas poorly dened borders suggest a malignant growth.• Isthelesionunilocularormultilocular(Fig.20.10)?• How has the lesion aected the teeth in the area?Has there been root resorption or root displacement (Fig.20.11)?• Canthelesionbeseeninthethreeplanes?Ifnot,thenfurther imaging is needed.• Can all the borders of the lesion be visualized (Fig.20.12)?Ifnot,thenfurtherimagingisnecessary.• If previous images of the lesion are available, what isthe rate of growth of the lesion? Certain lesions (e.g.,• Figure 20.9 Lesion with distinct borders. • Figure 20.10 Multilocular lesion. • Figure 20.11 Root resorption. • Figure 20.12 All the borders of the lesion are not seen. malignancies) have rapid growth, whereas cysts and benign lesions grow slowly.• Haveallimpactedteethandedentulousareasbeenvisu-alized?Justbecausetheareaisedentulousdoesnotmeanthat radiographs are unnecessary. An occult pathologic process may be present.Chapter Summary• edentalprofessionalis responsibleforexposingandinterpreting radiographs. e interpretation will ulti-mately lead to the formulation of a denitive diagnosis and treatment plan for the patient.• e three steps that are taken in forming a diagnosisare: (1) identication of an area or structure of concern, (2) radiographic interpretation of what has been identied (dierential diagnosis), and (3) a diagnosis 236 CHAPTER 20 Principles of Radiographic Interpretation• Dentalprofessionalsshouldbecapableofansweringtheproper diagnostic questions needed to formulate the appropriate diagnosis for their patients.based on the radiographic interpretation (denitive diagnosis).• elesionsthatareobservedontheradiographicimagesmust be described and documented in terms of their appearance(RO,RL,ormixed),size,andlocation.Chapter Review QuestionsMatchingMatch the term in Column A with the appropriate descrip-tion in Column B.Column A Column B1. Unilocular lesion2. Radiopaque lesion3. Bilateral lesion4. Radiolucent lesion5. Mixed lesion6. Multilocular lesion7. Unilateral lesion8. Vitality test a. Appears “light” on a radiograph b. A test used to decide if a tooth is vital or nonvital c. Occurs on one side of the oral cavity d. Appears light and dark on a radiograph e. Has one chamber f. Occurs on both sides of the oral cavity g. Has more than one chamber h. Appears dark on a radiographCritical Thinking ExerciseA new patient presents with pain and swelling in the area of tooth #12. e dentist requests that a periapical radiograph of tooth #12 be taken. e image reveals part of a radiolu-cency at the apex of tooth #12. Upon clinical examination, the dental professional notices exudate coming from the swellingonthebuccalsurfaceoftooth#12.Listthestepsthat should be taken in formulating a dierential diagnosis of the area of concern. Be sure to include the answers to the following diagnostic questions in your description. a. Whatisthepatient’schiefcomplaint? b. Whatwerethe clinical ndings thatpromptedthedentalprofessionaltorequesttheradiographs? c. What radiographic projections are available, andwhatadditionalimagesshouldbeordered? d. Have periapical and bitewing radiographs beentakenrecently? e. Isaboneorsofttissuepathologysuspected? f. Whatdoesthevitalitytestreveal? g. IsthelesionRL,RO,ormixed? h. Couldthesuspectedlesionbeananatomiclandmark? i. Whereisthelesionlocated? j. Isthelesionaunilateralorbilaterallesion? k. Whatisthesizeandshapeofthelesion? l. Arethebordersofthelesionwelldened? m. Isthelesionunilocularormultilocular? n. Howhasthelesionaectedtheteethinthearea? o. Canthelesionbeseeninthreeplanes? p. Canallthebordersofthelesionbevisualized?BibliographyIannucciJM,HowertonLJ:Dental radiography: Principles and tech-niques,ed5,StLouis,MO,2016,ElsevierSaunders.WhiteSC,PharoahMJ:Oral radiology: Principles and interpretation, ed7,StLouis,MO,2013,Mosby.

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