SHARON L. BROOKS. KATHRYN A. ATCHISON -...

SHARON L. BROOKS. KATHRYN A. ATCHISON

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&~ he decision to conduct a radiographic exami-

8.- nation should be based on the individualneeds of the patient. These needs are determined byfindings from the dental history and clinical examina-tion and modified by patient age and general health. Aradiographic examination is necessary when the historyand clinical examination have not provided enoughinformation for complete evaluation of a patient's con-dition and formulation of an appropriate treatmentplan. Radiographic exposures are necessary only when,in the dentist's judgment, it is reasonably likely that thepatient will benefit by the discovery of clinically usefulinformation on the radiograph.

radiographic examination centers on several factors,including the following:.Prevalence of the diseases that may be detected radi-

ographically in the oral cavity.Ability of the clinician to detect these diseases clini-

cally and radiographically.Consequences of undetected and untreated disease.Impact of asymptomatic anatomic and pathologic

variations detected radiographically on patient treat-ment.

The goal of dental care is to preserve and improvepatients' oral health while minimizing other health-related risks. Although the diagnostic information pro-vided by radiographs may be of definite benefit to thepatient, theyadiographic examination does carry thepotential for harm from exposure to ionizing radiation.One of the most effective means of reducing possibleharm is to avoid making radiographs that will not con-tribute information pertinent to patient care. The judg-ment that underlies the decision to make a

As a general principle, radiographs are indicatedwhen a reasonable probability exists that they willprovide valuable information about a disease that is notevident clinically. Conversely, radiographs are not indi-cated when they are unlikely to yield information con-tributing to patient care. Radiographic informationconsidered clinically useful includes data that are valu-able in detecting disease and in monitoring the pro-gression of known diseases.

For many clinical situations it is not readily apparentto the practitioner whether radiographs have a reason-able probability of providing valuable information. Inthese situations it is up to the practitioner's clinicaljudgment after weighing the patient factors to decidewhether radiographs are indicated.

The philosophy of taking radiographs only whenthere is a high probability of obtaining clinically usefulinformation has been advocated by all the organiza-

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266 PART IV IMAGING PRINCIPLES AND TECHNIQUES

Some dentists set up their practices such that newpatients are automatically seen first by the dentalhygienist, who takes a predetermined set of radiographsat- the first appointment, before the dentist sees thepatient. Although this may make efficient use of thedentist's time, it is contrary to the recommendations ofthe American Dental Association (ADA) that the selec-tion of radiographs should be based on the findings ofthe clinical examination. Performing a thorough exam-ination before radiographs are ordered should not be aninsurmountable obstacle for an efficient dental practice.

Regarding the issue of cost versus benefit of radi-ographs, for any individual patient there is little risk ofharm from a set of radiographs, even if no importantdiagnostic information is revealed. However, there is alarge societal cost, both in terms of health-care dollarsand radiation risk, if millions of dental patients receiveunproductive radiographic examinations, as wouldhappen if routine screening were widespread.

The philosophy of the authors of this chapter is thatradiographs should be based on the need for diagnos-tic information for patients on a case-by-case basis. Forthat reason, the next section will discuss some ofthe clinical situations that may call for a radiographicexamination.

tions responsible for developing or endorsing guide-'~lines for ordering radiographs. However, many dentistsuse radiographs as a screening tool, simply to see"what's there," without having a specific suspicion ofdisease arising from the dental history or clinical exam-ination. There are' probably a number of reasons fordoing this. Some dentists feel that they have not pro-vided an adequate service to their patients if theycannot assure them that they have searched diligentlyfor disease with all reasonable diagnostic methods,including radiographs. They may state that having com-plete information, whether it affects the treatment planor not, is of such benefit that it outweighs the risk ofthe radiation exposure. Other dentists raise medico-legal issues, stating fear of lawsuits if they fail to detectdisease. Others express concern about the effect on theefficiency of the dental office of the extended exami-nations required for prescribing radiographs based onsigns and symptoms.

The next few paragraphs will address these concerns.Unlike their use in dentistry, screening radiographs

are rarely used in medicine, with the exception ofmam-mography for women above a certain age or withincreased risk factors for breast cancer, and there is con-troversy over whether even this type of examinationshould be used as frequently as it is today. Breast canceris a relatively common, yet serious disease that shouldbe detected early, before the cancer becomes largeenough to be found clinically. On the other hand,diseases of the jaws (with the exceptions of caries,periapical and periodontal disease) are rare and con-centrated in certain ages, genders, and ethnicities.These diseases are unlikely to be discovered on routinescreening radiographs before they have produced signsor symptoms that could be found on a thorough clini-cal examination and history. Periodontal disease can bediagnosed clinically, although radiographs are used todetermine the extent of bone loss and presence ofother factors that may affect prognosis. Periapicaldisease is usually associated with extensive restorationsor caries that can be detected clinically. Dental caries

.on proximal surfaces, however, may not be detectableon clinical examination until it has reached anadvanced stage; thus this is one occult disease for whichscreening radiographs are considered appropriate.Regarding the threat of lawsuits for failure to diagnose,dentists who follow guidelines on radiographs devel-oped and/ or endorsed by authoritative bodies that helpestablish the standard of care should have no concerns.While lawsuits can be filed for many reasons, it isunlikely that they will be successful if it can be shownthat the practitioner did a thorough clinical examinationand history and carefully considered the guidelineswhen determining whether to order radiographs.

CARIES

Dental caries is the most common dental disease, affect-ing people of all ages. Although the caries prevalencerates of developed countries have been decreasing sincethe 1970s, probably partially as a result of the wide-spread use of fluoride, increasing numbers of olderadults are maintaining their teeth throughout their life-time, leaving them at risk for developing both coronaland root caries. Although occlusal, buccal, and lingualcarious lesions are reasonably easy to detect clinically,interproximal caries and caries associated with existingrestorations are much more difficult to detect with onlya clinical examination (see Chapter 16). Studies haverepeatedly demonstrated that clinicians using radi-ographs detect caries not evident clinically, both inenamel and in dentin. Although a radiographic exam-ination is very important for diagnosis of dental caries,the optimal frequency for such an examination shouldbe based on such mitigating features such as thepatient's age, medical condition, diet, oral hygienepractices, oral health status, and the nature of the cariesprocess itself.

Carious lesions demonstrate one of three behaviors:progression, arrest, or regression. Only about 50% oflesions progress beyond the initial, just-detectabledefect, and in most instances the lesions demonstrate aslow rate of progression through enamel (months to


267CHAPTER 14 GUIDELINES FOR PRESCRIBING DENTAL RADIOGRAPHS

ence of supernumerary teeth, usually mesiodens, ordevelopmentally absent teeth, usually second premolars(see Chapter 18).

-Few anomalies exist for which orthodontic treatmentor surgical correction or modification must start at anearly age. When the dentist suspects an abnormalityrequiring treatment, radiographs to confirm and local-ize it are not required until the time when the treat-ment is most appropriate. For example, a panoramicexamination of a 5-year-old child to determine the pres-ence or absence of permanent teeth may be ill-timed.Even though the examination provides evidence thatone or more second premolars or lateral incisors aredevelopmentally missing, this information usually doesnot influence the current treatment plan. When exam-ination for dental anomalies is appropriate, considerboth the radiation dose and anticipated diagnosticbenefit. Select the projections that best demonstratethe required diagnostic information. A panoramic radi-ograph of the lower face is usually best for observingthe presence or absence of teeth in all quadrants,although a periapical film or an occlusal film is suffi-cient for an examination limited to one area.

years). Mechanisms are also in use to enhance rem-ineralization of early enamel lesions. However, the rateof caries progression is significantly faster in deciduousthan in permanent enamel, and patients vary widely intheir rates of formation of caries and in their rates of.caries progression.

Because the presence of caries cannot be deter-mined with confidence by clinical examination alone,it is necessary to expose patients periodically throughbitewing radiography to monitor dental caries. Thelength of the exposure intervals varies considerablybecause of different patient circumstances. For mostpatients in good physical health with adequate oralhygiene, an infrequent radiographic examination isneeded to monitor dental caries. However, if the patienthistory and clinical examination suggest that the indi-vidual has a relatively high caries experience, shorterintervals allow careful monitoring of disease.

PERIODONTAL DISEASES

Some form of periodontal disease affects most peopleat some point during their life, gingivitis more often inyounger individuals and periodontitis more commonlyin older adults. Periodontal diseases are responsible fora substantial portion of all teeth lost. A consensus existsamong practitioners that radiographic examinationsplay an important role in the evaluation of patients withperiodontal disease after the disease is initially detectedon clinical examination (see Chapter 17). In additionto providing a picture of the extent of alveolar bonesupport for the dentition, radiographic examinationshelp demonstrate local factors that complicate thedisease, including the presence of gingival irritants suchas calculus and faulty restorations. Occasionally thelength and morphology of roots, visible on periapicalradiographs, are crucial factors in the prognosis of thedisease. These observations suggest that when clinicalevidence exists of periodontal disease, other than non-specific gingivitis, it is appropriate to make radiographs,generally a combination of periapicals and bitewings, to

~ help establish the severity of the disease. Follow-up radi-ographs after therapy is complete will help the clinicianmonitor the progression of disease and determine whe-ther the destruction of alveolar bone has been halted.

GROWTH AND DEVELOPMENTAND DENTAL MALOCCLUSION

Children and adolescents are often examined to assessthe growth and development of the teeth and jaws. Thisassessment considers the relationship of one jaw to theother and to the soft tissues. An examination of occlu-sion, growth, and development requires an individual-ized radiographic examination that may includeperiapicals or a panoramic examination to supplementany radiographs ordered to assess dental disease. Inaddition, a patient of any age group who is being con-sidered for orthodontic treatment may need other radi-ographs, such as a lateral or frontal cephalograph,occlusal view, carpal index, or temporomandibularjoint (TMJ) radiograph, depending on the clinical find-ings (Fig. 14-1).

The dentist who is the primary provider of ortho-dontic treatment should select the number and type ofradiographs needed. The needs of each patient shouldbe considered individually. Selected radiographsshould allow a maximal diagnostic yield with a minimalradiographic exposure after consideration of the clini-cal examination, the study of plaster models and pho-tographs, and the optimal time to initiate treatment.

DENTAL ANOMALIES

Abnormal formation of teeth may be manifested asdeviations in number, size, and composition. Theseabnormalities in dental development occur more fre-quently, and are more likely to have a serious impact,in the permanent dentition than in the primary. Themost frequently encountered anomalies are the pres-

OCCULT DISEASE

Uccult dzsease refers to dIsease that presents no clinicalsigns or symptoms. Occult diseases in the jaws include



Often a historic or clinical sign or symptom ofintraosseous disease suggests its presence. For instance,an unusual contour of bone or an absent third molar,not explained by a history of extraction, suggests thepossibility of an impaction with the potential for anassociated dentigerous cyst. Although patient historyand clinical signs and .symptoms do not always accu-rately predict the finding of dental and intraosseousfindings, the majority of these true occult diseases arenot clinically relevant or they are so rare that, exceptfor caries as described previously, one need not obtaina radiographic examination of the jaws solely to screenfor them in dentate individuals in the absence ofunusual clinical signs or symptoms. Caries is an excep-tion because of its much higher prevalence than otheroccult diseases.

There is considerable difference of opinion onwhether asymptomatic edentulous patients presentingfor routine denture construction should have screeningradiographs taken to look for occult disease. Severalstudies have demonstrated a relatively large number oflesions on radiographs of edentulous patients, includ-ing retained root tips and areas of sclerotic bone, butalmost all of these findings required no treatment anddid not affect outcome of care. For that reason, somerecommend no radiographs of edentulous patients ifthe clinical examination is negative for signs and symp-toms of disease. Others still believ.e that screening radi-ographs of these patients are of value.

There has been increasing interest in the last fewyears in using panoramic radiographs to screen patientsfor the presence of calcified atheromas in the bifurca-tion of the carotid artery, a finding which indicates anincreased risk for the development of a cerebrovascu-lar accident (stroke). The general consensus at thistime is that panoramic radiographs made for dentalpurposes should be evaluated for this calcification,particularly in patients over age 55, but that theseradiographs should not be made simply to screen foratheromas without other dental indications. (SeeChapter 27 for more details.)

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FIG. 14-1 An example of a clinical algorithm to orderradiographs for orthodontic patients. Selected radiographsare ordered after the dentist's consideration of the patient'shistory and clinical characteristics.

JAW PATHOLOGY

Imaging of known jaw lesions, such as fibroosseous dis-eases or neoplastic diseases, before biopsy and defini-tive treatment is also important for appropriatemanagement of the patient. For small lesions of thejaws, periapical and/or panoramic radiographs may beenough as long as the lesion can be seen in its entirety.If clinical evidence of swelling exists, some type of radi-ograph at 90 degrees to the original plane should bemade to determine whether there is expansion of thejaw or perforation of the buccal or lingual corticalbone. If lesions are too large to fit on standard dental

a combination of dental and intraosseous findings.Dental findings may include incipient carious lesions,resorbed or dilacerated roots, and hypercementosis.Intraosseous findings include osteosclerosis, uneruptedteeth, periapical disease, and a wide variety of cysts andbenign and malignant tumors (see Chapters 19-24).Small carious lesions, resorption of root structure, andbony lesions may go unnoticed until signs and symp-toms develop.

Although the consequences of some occult diseasesmay be quite serious, most serious diseases are rare.


269GUIDELINES FOR PRESCRIBING DENTAL RADIOGRAPHSCHAPTER 14

~:i'" cr canal or maxillary sinus; and the presence of structural

abnormalities such as undercuts that may affect place-ment or angulation of the implant (see Chapter 31).

Standard periapical and panoramic radiographs cansupply information regarding the vertical dimensionsof the bone in the proposed implant site. However,some type of cross-sectional imaging, either conven-tional tomography or CT, is recommended beforeimplant placement for visualization of importantanatomic landmarks, determination of size and path ofinsertion of implant, and evaluation of the adequacy ofthe bone for anchorage of the implant. Postoperativeevaluation of implants may be needed at later times tojudge healing, assess complete seating of fixtures, andensure continued health of the surrounding bone.

films, extend into the maxillary sinus or other portionsof the head outside the jaws, or are suspected of malig-nancy, additional imaging such as computed tomogra-phy (CT) is appropriate before biopsy (see Chapter 13).This type of imaging can define the extent of the lesion,suggest an operative" approach, and pro~de informa-tion about the nature of the lesion. The person per-forming the biopsy or managing the patient shouldorder the advanced images to decrease confusion andincrease coordination of care.

TEMPOROMANDIBULAR JOINT

Many types of diseases affect the TMJ, including con-genital and developmental malformations of themandible and cranial bones; acquired disorders such asdisk displacement, neoplasms, fractures, and disloca-tions; inflammatory diseases that produce capsulitis orsynovitis; and arthritides of various types, includingrheumatoid and osteoarthritis. The goal of TMJimaging, similar to that for imaging other body parts,should be to obtain new information that will influencepatient care. Radiologic examination may not beneeded for all patients with signs and symptoms refer-able to the TMJ region, particularly if no treatment iscontemplated (see Chapter 25). The decision ofwhether and how to image the joints should depend onthe results of the history and clinical findings, the clin-ical diagnosis, and results of prior examinations, as wellas the tentative treatment plan and expected outcome.

The cost of the examination and the radiation doseshould also influence the decision if more than onetype of examination can provide the desired informa-tion. For example, information about the status of theosseous tissues can be obtained from panoramic radi-ographs, plain films, conventional tomography, CT, andmagnetic resonance imaging (MRI). The subtlety of theexpected findings and the amount of detail requiredshould be considered when selecting the examinationto perform. If soft tissue information such as disk posi-tion is necessary for patient care, MRI or arthrography.is appropriate.

PARANASAL SINUSES

Because dentists are not usually the primary providersof treatment for acute or chronic sinus disease, thenecessity to perform sinus imaging may be limited ingeneral dental practice. However, because sinus diseasecan present as pain in the maxillary teeth and becauseperiapical inflammation of maxillary molars and pre-molars can also lead to changes in the mucosa of themaxillary sinus, circumstances occur in which thedentist needs to obtain an image of the maxillary sinus.Periapical and panoramic radiographs demonstrate thefloor of the maxillary sinus well, but ,yisualization ofother walls requires additional imaging techniques suchas occipitomental (Waters) view or CT. These radi-

.'ographs are best ordered by the person treating thepatient so that diagnostic and therapeutic measuresmay be coordinated (see Chapter 26).

IMPLANTS

An increasingly common method of replacing missingteeth is with osseointegrated implants, metal screws thatare inserted into the mandible or maxilla. Prostheticappliances 'Ire then affixed to the screws after a periodof healing. Preoperative planning is crucial to ensuresuccess of the implants. The dentist must evaluate theadequacy of the height and thickness of bone for thedesired implant; the quality of the bone, including therelative proportion of medullary and cortical bone; thelocation of anatomic structures such as the mandibular

TRAUMA

Patients who experience trauma to the oral region mayvisit a dentist for evaluation and management of theinjuries. For proper management it is important todetermine the full extent of the injuries. Periapicaland/ or panoramic radiographs are helpful for evalua-tion of fractures of the teeth. If a suspected root frac-ture is not visible on a periapical radiograph, a secondradiograph made with a different angulation may behelpful. A fracture that is not perpendicular to thebeam may not be detectable unless root resorptionis present. Thus a tooth with a history of traumashould be monitored and evaluated radiographicallyon a periodic basis, even if the original radiograph is

negative.Fractures of the mandible can frequen tly be detected

with panoramic radiographs, supplemented by imagesat 90 degrees such as a posteroanterior or reverse-Towne view (see Chapter 28). Trauma to the maxilla



«and midface may require CT for a thorough evaluati~.."Mfected patients are more likely to report to a hospitalemergency department than to a general dental office.The hospital may have a standard protocol for traumacases. Ideally the clinician responsible for managingcare determines. the appropriate radiographs for thespecific case.

cantly higher radiation dose per unit area exposed. Theclinician must. use clinical judgment to weigh thesefactors. Examples of all these radiographs can be foundin previous chapters.

INTRAORAL RADIOGRAPHS

Intraoral radiographs are examinations made byplacing the x-ray film within the patient's mouth duringthe exposure. These exposures offer the dentist a high-detail view of the teeth and bone in the area exposed.Such views are most appropriate for revealing cariesand periodontal and periapical disease in a localizedregion. A complete-mouth or full-mouth examination(FMX) consists of periapical views of all the tooth-bearing regions as well as interproximal views (seeChapter 8).

Periapical RadiographsPeriapical views show all of a tooth and the surround-ing bone and are very useful for revealing caries andperiodontal and periapical disease. These views may bemade of a specific tooth or region or as part of aFMX.

1\t:LJ\IIVt:

EXPOSURE*TYPE OF EXAMINATION COVERAGE RESOLUTION DETECTABLE DISEASE

Intraoral Radiographs

Extraoral Radiographs

Conventional tomography/slice Moderate Moderate 0.2-0.6 I MJ, Implant site assessment

MRI ISroad Moderate Soft tissue disease, TM)

'I'" f"""II"""" ""ume use or t-speeo rum ana rectangular COllimation tor periapical tilms, round collimation for bitewings and occlusal views, and rare-earthscreens for panoramic examinations. With D-speed film the intraoral values are more than doubled compared with F-speed film, and with round collimation theperiapical values increase by 2.5 times compared with rectangular collimation. Frederiksen N, Benson B, Sokolowski T: Effective dose and risk assessment fromcomputed tomography of the maxillofacial complex, Dentomaxillofac Radiol 24:55, 1995; Scaf G et al: Dosimetry and cost of imaging osseointegrated implantswith film-based and computed tomography, Oral Surg Oral Med Oral Pathol Oral Radiol and Endod 83:41, 1997; White SC: 19~2 assessment of radiation risksfrom dental radiology, Dentomaxillofac Radiol 21 :118, 1992.

LimitedlimitedLimited

HighHighHigh

110

14-17

PeriapicalBitewingsFull-mouth periapical

Occlusal Moderate High

c.:aries, periodontal disease, occult diseaseCaries, periodontal bone levelCaries, periodontal disease, dental anomalies,

occult diseaseDental anomalies, occult disease, salivary stones,

expansion of jaw

Mter concluding that a patient requires a radiograph,the dentist should consider which radiographic exami-nation is most appropriate to meet all the patient'sdiagnostic and treatment planning needs. A variety ofradiographic 'projections is available. In choosing one,the dentist should consider the anatomic relationships,the size of the field, and the radiation dose from eachview. Table 14-1 summarizes the more common types ofradiographic examinations for general dental patientsand factors to consider in choosing the most appropri-ate one. For example, a panoramic radiograph providesbroad area coverage with moderate resolution. Intrao-ral films give more detailed information but a signifi-



imaged by periapical radiographs. Therefore, when afull-mouth set of radiographs is available, a panoramicexamination is usually redundant because it doesnot add information that alters the treatment plan.However, situations may exist in which a panoramicradiograph may be preferred over a periapical exami-nation, such as for a patient with unerupted thirdmolars that are to be surgically removed. Panoramicviews are most useful when the required field of view islarge but the need for high resolution is of less impor-tance. Although the selection of a radiographic exami-nation should be based on the extent of the expectedinformation it is likely to provide, the relatively low doseof radiation from the panoramic examination shOllldalso De a qualifying factor.

Interproximal Radiographs :~Interproximal views (bitewings) show the coronalaspects of both the maxillary and mandibular dentitionin a region, as well as the surrounding crestal bone.These views are. most useful for revealing proximalcaries and evaluating the height of the alveolar bonycrest. They can be made in either the anterior or pos-terior region of the mouth.

Occlusal RadiographsOcclusal views are intraoral radiographs in which thefilm is positioned in the occlusal plane. They are oftenused in lieu of periapical views in children because thesmall size of the patient's mouth limits film placement.In adults, occlusal radiographs may supplement peri-apical views, providing visualization of a greater area ofteeth and bone. They are useful for demonstratingimpacted or abnormally placed maxillary anterior teethor visualizing the region of a palatal cleft. Occlusal viewsmay also demonstrate buccal or lingual expansion ofbone or presence of a sialolith in the submandibularduct.

Advanced Imaging ProceduresA variety of advanced imaging procedures such asCT, MR!, ultrasonography, and nuclear medicinescans may be required in specific diagnostic situa-tions. These techniques are discussed in Chapter 13,although in general the dentist refers the patientto a hospital or other imaging center for these proce-dures, rather than performing them in the dentaloffice.EXTRAORAL RADIOGRAPHS

Extraoral radiographs are examinations made of theorofacial region using films located outside the mouth.The relationships among patient position, film location,and beam direction vary, depending on the specificradiographic information desired. The standard tech-nique for making several extraoral radiographs is dis-cussed in Chapter 11. Only the panoramic radiograph isdescribed here, because it has common use as a radi-ographic examination for general dental patients.

The dental profession has issued guidelines recom-mending which radiographs to make and how often torepeat them:.Make radiographs only after a clinical examination..Order only those radiographs that directly benefit

the patient in terms of diagnosis or treatment

plan..Use the least amount of radiation exposure necessary

to generate an acceptable view of the imaged area.

PREVIOUS RADIOGRAPHS

Most patients have been seen previously by a dentistand have already had radiographs made. These radi-ographs are helpful regardless of when they wereexposed. If they are relatively recent, they may be ade-quate to the diagnostic problem at hand. Even if theywere made so long ago that they are not likely to reflectthe current status of the patient, they may still proveuseful. These previous radiographs may demonstratewhether a condition has worsened, has remainedunchanged, or has shown healing, such as in the pro-gression of caries or periodontal disease.

Panoramic RadiographsPanoramic radiographs provide a broad view of thejaws, teeth, maxillary sinuses, nasal fossa, and TMJs (seeChapter 10). They show which teeth are present, theirrelative state of development, presence or absence ofdental abnormalities, and many traumatic and patho-logic lesions in bone. Panoramic radiographs are thetechnique of choice for initial examinations of edentu-lous patients. Because this system is an extraoral tech-nique and uses intensifying screens, the resolution ofthe images is less than with the intraoral nonscreenfilms (see Chapter 4). Panoramic radiographs are alsosusceptible to artifacts from improper patient position-ing thaLuegatively affect the image. Consequently thissystem is generally considered inadequate for inde-pendent diagnosis of caries, root abnormalities, and

periapical changes.In the great majority of dental patients, oral disease

involving the teeth or jawbones lies within the area


PART IV IMAGING PRINCIPLES AND TECHNIQUES

"/#ADMINISTRATIVE RADIOGRAPHS ..)-

Administrative radiographs are those made for reasonsother than diagnosis, including those made for aninsurance company or for an examining board. Theauthors believe tnat it is appropriate to expose patientsonly when it benefits their health care. Most adminis-trative radiographs do not serve such an objective.Unfortunately, this recommendation is often notadhered to in practice, and dentists are left to sort outthe most appropriate criteria to use in their practices.

mandate a radiograph: some clinical evidence of anabnormality that requires further evaluation for a com-plete assessment or a high probability of disease thatwarrants a screening examination.

Selection criteria for radiographs are those signs orsymptoms found in the patient history or clinical exam-ination that suggest that a radiographic examination

will yield clinically useful information. A key concept in

the use of selection criteria is recognition of the need

to consider each patient individually. Prescription of

radiographs should be decided on an individual basisaccording to the patient's demonstrated need.

The guidelines incJude a description of clinical situ-ations in which radiographs are likely to contribute to

the diagnosis, treatment, or prognosis. Two exampleshighlight the differences between ordering radiographs

for dental diseases with clinical signs and symptoms and

dental diseases with no clinical indicators but high

prevalences. In the first case, consider a patient with a

hard swelling in the premolar region of the mandible

with expansion of the buccal and lingual cortical plates.

The clinical sign of swelling alerts the dentist to the

need for a radiograph to determine the nature of the

abnormality causing the swelling.An example of the second situation is the patient

who comes seeking general dental care after having not

seen a dentist for many years. Even without clinical evi-

dence of caries, bitewings are indicated because of the

prevalence of dental caries in the population. Because

this patient has not had interproximal radiographs for

many years, it is reasonable to assume that the p;atient

may benefit from the radiograph by the detection of

interproximal caries. Although no clinical signs existthat predict the presence of caries, the dentist relies onclinical knowledge of the prevalence of caries to decidethat this radiograph has a reasonable probability offinding disease.

Without some specific indication, it is inappropriateto expose the patient 'just to see if there is somethingthere." The major exception to this rule is the use ofinterproximal films for caries, in which no clinical signsexist of early lesions. The probability of finding occultdisease in a patient with all permanent teeth eruptedand no clinical or historic evidence of abnormality orrisk factors is so low that making a periapical radi-ographic survey just to look for such disease is not indi-cated.

Use of Guidelines to OrderDental Radiographs

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At any time patients generally have a combination ofdiseases that the clinician must consider. Thereforeguidelines specify not only which examinations to orderbut also which specific patient factors influence thenumber and type of x-ray films to order.

A panel of individuals was convened in the mid-1980sat the request of a branch of the Food and Drug Admin-istration (FDA) to develop a set of guidelines (Table 14-2) for the making of dental radiographs. The paneladdressed the topic of appropriate radiographs for anadequate evaluation of a new or recall asymptomaticpatient seeking general dental care. The guidelinesdescribe circumstances (patient age, medical anddental history, and physical signs) that suggest the needfor radiographs. These circumstances are called selectioncriteria. The guidelines also suggest the types of radi-ographic examinations most likely to benefit thepatient in terms of yielding diagnostic information.They recommend that radiographs not be made unlesssome expectation exists that they will provide evidenceof diseases that will affect the treatment plan. TheAmerican Dental Association recommends use of theguidelines.

The guidelines that were developed by the FDApanel in the 1980s form the basis of the recommenda-

.tions in this chapter. However, over the years some crit-icisms have arisen of certain portions of the guidelines,and recently interest has been expressed in revisiting,and perhaps revising, the document. Although somechanges may be made in specific recommendations, itis unlikely that the basic principles underlying theguidelines will be altered. Therefore, the conceptsshould still be considered valid.

Central to the guidelines is the idea that dentistsshould expose patients to radiation only when they rea-sonably expect that the resulting radiograph willbenefit patient care. Accordingly, two situations

PATIENT EXAMINATION

The ordering of radiographs requires a reasonableexpectation that they will provide information that willcontribute to solving the diagnostic problem at hand.Accordingly, the first step is a careful examination of


273CHAPTER 14 GUIDELINES FOR PRESCRIBING DENTAL RADIOLRAPHS

~

supplemented WIth eIther periapiCal or occlusal views(8 to 12 exposures) or a panoramic view. At this stageof development a panoramic projection is usually theview of choice because it offers the most general infor-mation with the lowest dose of ionizing radiation. Someclinicians express concern that complete coverage of alltooth-bearing areas is not warranted without a specificindication.

The guidelines group adolescents and dentate adultstogether to identify the kind and extent of appropriateradiographic examination. The guidelines recommendthat these patients receive an individualized examina-tion consisting of interproximal views and periapicalviews selected on the basis of specific historical or clin-ical indications. The presence of generalized dentaldisease often indicates the need for a full-mouth exam-ination. Alternatively, the presence of only a few local-ized abnormalities or diseases suggests that a morelimited examination consisting of interproximal andselected periapical views may suffice. In circumstanceswith no evidence of current or past dental disease,only interproximal views may be necessary for cariesexamination.

For the edentulous patient it may be appropriate toobtain a radiographic examination of all the tooth-bearing areas, either by periapical or panoramic radi-ographs. However, as discussed above, there is noconsensus on this recommendation. If available, thepanoramic projection usually provides the requiredinformation at a reduced radiation dose.

the patient, including transillumination of the anteriorteeth to evaluate for interproximal decay. The clinicalexamination provides indications as to the nature andextent of the radiographic examination appropriate tothe situation.

A team of dentists tested the ability of the ADA guide-lines to reduce the number of intraoral radiographswhile still offering adequate diagnostic information.This testing of the use of selection criteria demon-strated that a small but significant number of radi-ographic findings was not 100% covered in the anteriorregion if only posterior interproximal and selected peri-apical radiographs were used. The testing suggestedthat anterior interproximal radiographs or anteriorperiapicals are also indicated to detect interproximalcaries and periodontal disease in the anterior region,specifically for patients with high levels of dentaldisease. A panoramic radiograph could be made inplace of the periapical radiographs to supplement theposterior bitewings if the totality of the disease expectedindicates a broad area of coverage and fine detail is not

required.In the guidelines patients are classified by stage of

dental development, by whether they are being evalu-ated for the first time (without previous documenta-tion) or being reevaluated during a recall visit, and byan estimate of their risk for having dental caries or peri-odontal disease. A footnote to Table 14-2 also outlinessome other clinical findings that indicate when radi-ographs are likely to contribute to a complete descrip-tion of the asymptomatic patient.

Applying these guidelines to the specific circum-stances with each patient requires clinical judgmentand an amalgamation of knowledge, experience, andconcern. Clinical judgment is also required to recog-nize situations that are not described by the guide-lines but in which patients will need radiographsnonetheless.

Kecall VISitPatients who are returning after initial care requirecareful examination before determining the needfor radiographs. As at the initial examination, obtainselected periapical views if any of the historical or clin-ical signs or symptoms listed in the footnote to Table14-2 are present and need further evaluation.

The guidelines recommend interproximal radi-ographs for recall patients to detect interproximalcaries and monitor the status of alveolar bone loss. Theoptimal frequency for these views depends on the ageof the patient and the probability of finding either of

these two diseases. If the patient has clinically demon-strable caries or the presence of high-risk factors forcanes ,POOT diet, pOOT oTal hygiene, and those listed inthe footnote to Table 14-2), then bitewings are exposedat fairly frequent intervals. Obtain bitewings for chil-dren at 6-month intervals until no carious lesions artclinically evident. For the adolescent at high risk foJcaries, the guidelines recommend bitewings at 6- to 12.month intervals; for the high-risk adult, at 12- to 18month intervals. The recommended intervals artlonger for individuals not at high risk for caries: 12 tc

Initial VisitThe guidelines recommend that a child with primary

.,. dentition who is cooperative and has closed posteriorcontacts have only interproximal radiographs toexamine for caries. Additional periapical views are rec-ommended only in the case of clinically evident diseases'an\\j Oy '&pe\:.\n\:. fi\'&'-Oll\:. OY \:.\\n\\:.'a\ \n\\\\:.'auon'& ,&U\:.ll 'a~

those listed at the footnote of Table 14-2. If the molalcontacts are not cloged, interproximal radiographs artnot necessary because the proximal surfaces may btexamined directly.

The guidelines recommend radiographic coveragtof all tooth-bearing areas for a child with transitionadentition (after eruption of the first permanent tooth6 to 8 years of age). This usually consists of bitewing'



The recommendations in this table are subject to clinical judgment and may not apply to every patient. They are to be used by dentists onlyafter reviewing the patient's health history and completing a clinical examination. They do not need to be altered because of pregnan~

.CHILD

PRIMARY DENTITION (BEFORE TRANSITIONAL DENTITION (AFTER

ERUPTION OF FIRST PERMANENT MOLAR) ERUPTION OF FIRST PERMANENT MOLAR)

New PatientAll new patients to assess Posterior bitewing examination if proximal surfaces Individualized radiographic examination consisting ofdental diseases and of primary teeth cannot be visualized or probed periapical and/or occlusal views and posterior bitewingsgrowth and development or panoramic examination and posterior bitewings

Recall Patient

No clinical caries and no Posterior bitewing examination at 12- to 24-month Posterior bitewing examination at 12- to 24-monthhigh-risk factors for caries intervals if proximal surfaces of primary teeth intervals

cannot be visualized or probed

Growth and development Usually not indicatedassessment

Individualized radiographic examination consisting ofa periapical and/or occlusal or panoramic examination

9. Clinically suspected sinus pathology10. Growth abnormalities11. Oral involvement in known or suspected systemic

disease12. Positive neurologic findings in the head and neck13. Evidence of foreign objects14. Pain and/or dysfunction of the TMJ1.5. Facial asymmetry

.Clinical situations for which radiographs may be indicated include the following:

Positive historical findings: Positive clinical signs or symptoms:1. Previous periodontal or endodontic therapy 1. Clinical evidence of periodontal disease2. History of pain or trauma 2. Large or deep restorations3. Familial history of dental anomalies 3. Deep carious lesions4. Postoperative evaluation of healing 4. Malposed or clinically impacted teeth5. Presence of implants 5. Swelling

6. Evidence of facial trauma7. Mobility of teeth8. Fistula or sinus tract infection

for obtaining it. An example of a clinical algorithm forordering radiographs before orthodontic treatment isshown in Fig. 14-1, using guidelines endorsed by theAmerican Academy of Orthodontics. Because guide-lines for ordering radiographs for other situations arenot as well developed, the dentist must rely on clinicaljudgment.

SPECIAL CONSIDERATIONS

24 months for the child, 18 to 36 months for the ado-lescent, and 24 to 36 months for the adult. Note thatindividuals can change their risk category, going fromhigh to low risk or the reverse. Similarly, patients witha history or clinical evidence of periodontal diseasemore serious than nonspecific gingivitis should have acombination of periapical and interproximal radi-ographs to allow appropriate monitoring at intervalsdependent on the clinical findings.

A radiographic examination may be required in anumber of other situations, such as for patients con-templating orthodontic treatment or patients withintraosseous lesions. The goal should be to obtain thenecessary diagnostic information with the minimal radi-ation dose and financial cost, which can be substantialfor advanced imaging procedures such as MR!. Thedentist should determine specifically what type of infor-mation is needed and the most appropriate technique

PregnancyOccasionally it is desirable to obtain radiographs of awoman who is pregnant. The x-ray beam is largely con-fined to the head and neck region in dental x-rayexam-inations; thus the fetal exposure is only about IIlGy fora full-mouth examination. This exposure is quite smallcompared with that received normally from naturalbackground sources. Accordingly, apply the guidelines

Periodontal disease orhistory of periodontaltreatment

Individualized radiographic examination consisting of selected periapical and/or bitewing radiographs forareas where periodontal disease (other than nonspecific gingivitis) can be demonstrated clinically



ADULTADOLESCENT

PERMANENT DENTITION (BEFORE

ERUPTION OF THIRD MOLARS) DENTULOUS EDENTULOUS

Individualized radiographic examination consisting of posterior bitewings and selectedperiapicals; a full-mouth intraoral radiographic examination is appropriate when patientpresents with clinical evidence of generalized dental disease or a history of extensive

dental treatment.

Full-mouth intraoral radiographic examinationor panoramic examination

Posterior bitewing examination at 24- to36-month intervals

Not applicablePosterior bitewing examination at 18- to36-month intervals

Usually not indicatedUsually not indicatedPeriapical or panoramic examination toassess developing third molars

16. Abutment for fixed or removable partial prosthesis17. Unexplained bleeding18. Unexplained sensitivity of teeth19. Unusual eruption, spacing, or migration of teeth20. Unusual tooth morphology, calcification, or color21. Missing teeth with unknown reason

tpatients at high risk for caries may demonstrate any of the following

1. High level of caries experience 8. Poor family dental health2. History of recurrent caries 9. Developmental enamel defects3. Existing restorations of poor quality 10. Developmental disability4. Poor oral hygiene 11. Xerostomia5. Inadequate fluoride exposure 12. Genetic abnormality of teeth6. Prolonged nursing (bottle or breast) 13. Many multi surface restorations7. Diet with high sucrose frequency 14. Chemotherapy or radiation therapy

to pregnant patients just as with other patients, usingan appropriate leaded apron to shield the abdominalarea.

ingly, carefully follow patients who have had radiationtherapy to the oral cavity because they are at special riskfor dental disease.

Radiation Therapy,Patients with a malignancy in the oral cavity or perioralregion often receive radiation therapy for their disease.Some oral tissues receive 50 Gy or more. Although suchpatients are often apprehensive about receiving addi-tional exposure, dental exposure is insignificant com-pared with what they have already received. Theaverage skin dose from a dental radiograph is approxi-mately 3 mQr, less if faster film or digital imaging isused. Furthermore, patients who have received radia-tion therapy may suffer from radiation-induced xeros-tomia and thus are at a high risk for developingradiation caries, which may produce serious conse-quences if extractions are needed in the future. Accord-

EXAMPLES OF USE OF THE GUIDELINES

Consider the ways in which the guidelines can beapplied to different clinical situations:.The first visit of a 5-year-old boy to a dental office-

A careful clinical examination reveals that the patientis cooperative and that the posterior teeth are incontact. Posterior bitewings are recomrnended todetect caries. If all of this patient's teeth are present,no evidence exists of decay, a reasonably good diet isbeing observed, and the parent(s) seem(s) well moti-vated to promote good oral hygiene, no further radi-ographic examination is required at this time.Radiographs for the detection of development abnor-

Posterior bitewing examination at 12- to18-month intervals

Not applicablePosterior bitewing examination at 6- to12-month intervals or until no cariouslesions are evident

Individualized radiographic examination consisting of selected periapical and/orbitewing radiographs for areas where periodontal disease (other than nonspecific

gingivitis) can be demonstrated clinically

Not applicable



malities are not in order at this age because a com;plete appraisal cannot be made at 5 years. Even if itcould be made, it is too early to initiate treatment forsuch abnormalities.

.A 25-year-old woman receiving a 6-month checkupafter her last tI"eatment for a fractured incisor-Nocaries is evident on interproximal radiographs made6 months ago; currently no clinical signs suggestcaries, nor does the patient have high-risk factors forcaries. No evidence exists of periodontal disease orother remarkable signs or symptoms in general orassociated with the recently fractured tooth. As longas the fractured incisor shows normal vitality testing,no radiographs are recommended for this patient. Ifthe incisor is nonvital, expose a periapical view of thistooth.

.A 45-year-old man returning to the dentist's officeafter 1 year-At his last visit you placed two mesial,occlusal, distal (MOD) amalgam restorations on pre-molars and performed root canal therapy on number30. The patient has a 5-mm pocket in the buccal fur-cation of number 3 but no other evidence of peri-odontal disease. The guidelines recommend that thispatient receive interproximal radiographs to seewhether he still has active caries and periapical viewsof numbers 3 and 30 to evaluate the extent ofthe periodontal disease and periapical disease,

respectively..A 65-year-old woman coming to your office for the

first time-No previous radiographs are available. Ahistory exists of root canal therapy in two teeth,although the patient is not aware which teeth weretreated. Clinical examination reveals multiple cariousteeth, multiple missing teeth, and pockets of morethan 3 mm involving most of the remaining teeth.The guidelines recommend a full-mouth examina-tion, including interproximal radiographs, for thispatient because of the high probability of findingcaries, periodontal disease, and periapical disease.

BIBLIOGRAPHY

GUIDELINES FOR ORDERING RADIOGRAPHS

Akerblom A, Rohlin M, Hasselgren G: lndividualisedrestricted intraoral radiography versus full-mouth radiog-raphy in the detection of periradicular lesions, Swed DentJ 12:151, 1988.

Atchison KA,;Luke LS, White SC: An algorithm for orderingpretreatment orthodontic radiographs, Am J OrthodDentofac Orthop 102:29, 1992.

ADA Council on Scientific Affairs: An update on radiographicpractices: information and recommendations, JADA132:234, 2001.

Atchison KA et al: Assessing the FDA guidelines for orderingdental radiographs,]ADA 126:1372, 1995.

Bohay RN, Stephens RG, Kogon SL: A study of the impact ofscreening or selective radiography on the treatment andpost delivery outcome for edentulous patients, Oral SurgOral Med Oral Pathol Oral Radiol Endod 86:353,1998.

Brooks SL: A study of selection criteria for intraoral dentalradiography, Oral Surg Oral Med Oral Pathol 62:234, 1986.

Brooks SL et al: Imaging of the temporomandibular joint: aposition paper of the American Academy of Oral andMaxillofacial Radiology, Oral Surg Oral Med Oral PatholOral Radiol and Endod 83:609, 1997.

Bruks A et al: Radiographic examinations as an aid to ortho-dontic diagnosis and treatment planning, Swed Dent]23:77,1999.

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Keur.ll: Radiographic screening of edentulous patients: senseor nonsense? A risk-benefit analysis, Oral Surg Oral MedOral PathoI62:463, 1986.

Luke LS et al: Orthodontic residents' indications for use ofthe lateral TM] tomogram and the posteroanterior cephalo-gram,] Dent Educ 61:29,1997.

Molander B: Panoramic radiography in dental diagnostics,Swed Dent] SuppII19:1, 1996.

Pitts NB, Kidd EA: Some of the factors to be considered inthe prescription and timing of bitewing radiography in thediagnosis and management of dental caries,] Dent 20:74,1992.

Rushton VE, Horner K, Worthington HV: Routine panoramicradiography of new adult patients in general dental prac-tice: relevance of diagnostic yield to treatment and identi-fication of radiographic selection criteria, Oral Surg OralMed Oral Pathol Oral Radiol Endod 93:488, 2002.

Stephens RG, Kogon SL: New U.S. guidelines for prescribingdental radiographs: a critical review, ] Can Dent Assoc56:1019, 1990.

Tyndall DA, Brooks SL: Selection criteria for dental implantsite imaging: a position paper of the American Academy ofOral and Maxillofacial Radiology, Oral Surg Oral Med OralPathol Oral Radiol 89:630, 2000.

U.S. Department of Health and Human Services: The selec-tion of patients for x-ray examinations: dental radiographicexaminations, DHHS Publication FDA 88-8273, Rockville,MD, 1987.

White SC et al: Parameters of radiologic care: an officialreport of the American Academy of Oral and MaxillofacialRadiology, Oral Surg Oral Med Oral Pathol Oral RadiolEndod 91:498, 2001.

DISEASE DETECTIONAtchison K et al: Efficacy of the FDA selection criteria for radi-

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Carter LC et al: Use of panoramic radiography among anambulatory dental population to detect patients at risk ofstroke,]ADA 128:977,1997.


277CHAPTER 14 GUIDELINES FOR PRESCRIBING DENTAL RADIOGRAPHS

White SC et al: Efficacy of FDA guidelines for ordering radi-ographs for caries detection, Oral Surg Oral Med OralPathol 77:531, 1994.

RADIATION DOSAGE AND EFFECTSFrederiksen N, Benson B, Sokolowski T: Effective dose

and risk assessment from computed tomography of themaxillofacial complex, Dentomaxillofac Radiol 24:55,1995.

Gonad doses and genetically significant dose from diagnosticradiology: U.S., 1964 and 1970, DHEW Publication (FDA)76-8034, Washington, D.C., 1976.

scar Get al: Dosimetry and cost of imaging osseointegratedimplants with film-based and computed tomography, OralSurg Oral Med Oral Pathol Oral Radiol Endod 83:41,1997.

White SC: 1992 assessment of radiation risks from dental radi-ology, Dentomaxillofac RadioI21:118, 1992.

Friedlander AH: Identification of stroke-prone patients bypanoramic and cervical spine radiography, Dentomaxillo-fac Radiol 24:160, 1995.

Hall WB: Decision making in periodontology, ed 3, St. Louis,

1998, Mosby.Moles DR, Downer MC: Optimum bitewing examination

recall intervals assessed by computer simulation, CommunDent Health 17:14, 2000.

Reddy MS et al: Periodontal disease progression, ] Periodon-tol 71:1583, 2000.

Shwartz M et al: A longitudinal analysis from bitewing radi-ographs of the rate of progression of approximal cariouslesions through human dental enamel, Archs Oral BioI29:529, 1984.

White SC et al: Clinical and historical predictors of dentalcaries on radiographs, Dentomaxillofac Radiol 24:121,1995.


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