An analysis of the scientific basis for the radiographic guideline for new edentulous patients

An analysis of the scientific basis for the radiographic guideline for new edentulous patients S. L. Kogon, DDS, MSc, a R. G. Stephens, DDS, MSc, b and R. N. Bohay, DMD, MSc, MRCD(C), c London, Ontario, Canada UNIVERSITY OF WESTERN ONTARIO

The FDA Radiology Guideline for the new edentulous patient recommends an initial survey of the arches. In the process of developing this recommendation, the expert panel reviewed the available literature and concluded that there was sufficient evidence to warrant screening radiography rather than selective radiography, which is the principle on which all the other recommendations are based. Our evaluation of the literature used by the panel for the edentulous recommendation identifies critical errors in the analysis of the data. Factors such as a vague definition of abnormality and a geographically diverse sample population might have led the expert panel to suggest a very conservative recommendation for this group of patients. The recommendation failed 1o consider the treatment impact of findings and was based simply on the large number of observations, regardless of their treatment or pathologic significance. However, in studies in which treatment is considered, it is clear that screening radiography for new edentulous patients does not yield sufficient clinically relevant information to support the guideline. (Oral Surg Oral Med Oral Pathei Oral Radiol Ended 1997;83:619-23)

The application of radiography for diagnosis in Medicine and Dentistry has been the focus of guidelines for many years. In the 1960s, in response to concerns about the risks of patient exposure, the American Dental Association (ADA) developed guidelines with the objective of reducing the number of unproductive radiographic examinations. 1 In the following years, the ADA evolved the principle of individualizing the radiographic prescription (selective radiography) based on the findings of a preceding clinical examination. 2 In 1988, an expert panel established by the U.S. Food and Drug Administration (FDA) published a detailed set of guidelines to assist dentists in applying this principle) For all patient categories but one, the recommendations endorsed the principle of selective radiography based on the clinical diagnostic needs of the individual patient. However, for the initial examination of new edentulous patients, the expert panel recommended a radiographic examination composed of either a full-mouth intraoral or a panoramic survey) One of the desirable attributes in the current method for practice guideline development is a scheduled process for review of the scientific literature to determine whether revision of a guideline is aProfessor, Division of Oral Medicine and Radiology. bprofessor Emeritus, Division of Oral Medicine and Radiology. CAssociate Professor and Chairman, Division of Oral Medicine and Radiology. Received for publication Sept. 3, 1996; returned for revision Oct. 14, 1996; accepted for publication Jan. 2, 1997. Copyright © 1997 by Mosby-Year Book, Inc. 1079-2104/97/$5.00 + 0 7/16/80436

warranted. 4 This article presents a review and an analysis of the literature on which the expert panel based its recommendation for the new edentulous patient. In addition, we reviewed studies published since 1988 in order to assess the impact of new data on this recommendation. ANALYSIS OF LITERATURE SUPPORTING THE GUIDELINE RECOMMENDATION

In its justification of screening radiography for the new edentulous patient, the panel stated "Several studies show that 33 to 41 percent of edentulous patients examined exhibited pathological conditions.' ,5 Four studies were cited by the panel, one from the United States, 6 and one each from Switzerland, 7 Greece? and Australia? Table I summarizes the results of these studies in categories common to all of the reports. In addition, these studies recorded other observations such as anatomic variations, calcified lymph nodes, and mucosal changes in the maxillary sinus. Although the percentage of findings in the four studies cited is impressive, surprisingly the significance of these observations on dental treatment or general health was not assessed. The U.S. study reported the prevalence of '~positire radiographic findings" in panoramic radiographs of patients without signs or symptoms. 6 Four of the categories of findings were clearly identified, but two were given only the general descriptive terms of radiolucencies and radiopacities without diagnostic interpretation. This is a critical omission because most incidental radiopacities in the alveolar processes are idiopathic osteosclerosis of no significance in treat619

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May 1997 lrable I. Surveys of edentulous patients used to develop the FDA guideline Categories in Common to All Studies*

Authors Perrelet et al. 1977 (Switzerland) 7 Spyropoulos et al. 1981 (Greece) 8 Jones et al. 1985

Percentage of subjects with findings

Total number of findings

Root tip (%)

Unerupted teeth (%)

287

41

155

39

15

368

37

178

64

114

34

39

1,135

61

465

Number of subjects

Foreign bodies (%)

Radiopacities (%)

Radiolucencies

6

25

157

19

2

3

11

36

3

26

31

5

77

8

3

12

2:~

(%)

(u.s.) 6 Keur et al. 1987 (Australia)9

*Most studies also listed anatomic variations, lymph node calcifications and sinus changes such as retention cysts and mucositis. ~'Includes 5 cysts, 7 'periapical lesions. 5;9 cysts.

ment planning. In addition, radiolucencies, unless identified, could be anything from a common anatomic variation to a pathologic lesion. The foreign bodies were amalgam scrap and one wire suture in a healed fracture for which no treatment would be indicated. Finally, for the most common findings, root fragments and unerupted teeth, unless there is pathologic change or its location is on or very near the surface of the ridge, surgery is not indicated. Although the authors did not assess the impact of their observations on treatment, they concluded that, " T h e high incidence of positive findings suggests not only the need for radiographic examination of all patients but also the frequency with which the dentist is faced with the necessity of modifying the treatment plan.' ,6 This statement is unsupported by the data presented. The authors of the Swiss study described some of their observations in more precise radiographic terms .7 For example, the retained roots were subdivided into imbedded (n = 31) or superficial fragments (n -- 13). As in the U.S. study, the foreign bodies were amalgam scrap, and the radiopacities were not identified. The authors stated that cysts, visible root fragments, and sequestra would require surgery. However, for all other findings, treatment would not be justified in elderly patients because of the risk, although patients should be informed. Because this was not a longitudinal study, future treatment needs were not reported. Nonetheless, they described all the findings that justify the use of an initial panoramic radiograph as "significant lesions." Again, this conclusion cannot be supported by the data that clearly indicated that only a small percentage of their observations required therapy. In the Greek study, 8 the percentage of patients with root fragments was 2.5 times that found in the U.S. s t u d y and the percentage of patients with unerupted

teeth was nine times more. These substantial differences in prevalence suggest significant differences in the population with respect to dental care. Although all findings were described as "pathologic lesions," 85% were roots, unerupted teeth, and metal scrap listed as foreign bodies. As in the U.S. study, the authors concluded that because one in three patients had pathologic conditions, " . . . it is imperative to examine edentulous jaws radiographically prior to the construction of complete dentures." The Australian study differed from the other three in that the radiographic observations were precisely defined. 9 O f the 80 patients with "radiopacities," 75 of these were identified as either sclerotic areas or foreign bodies, mostly amalgam scrap. As in the three previous studies cited, the authors did not determine the number of patients for w h o m the radiographic observations had an impact on treatment planning. However, in a separate article not referenced by the FDA panel, the principal author did comment on the relevance of the findings. The author reported that 34% of the sample were referred to an oral surgeon for consultation and "in most cases surgical treatment was carried out."l° The number of occult findings requiring surgical treatment was not stated. As in the Greek study, the disproportionate number of root fragments indicates fundamental differences between this sample and the U.S. sample.

ANALYSIS OF LITERATURE SINCE 1988 In addition to a reevaluation of the studies that were the foundation for the expert panel's recommendation, a review of the literature published since the release of the FDA guidelines in 1988 is required as part of the guideline development process (Table II). The presentation of findings in these studies differ from those in the earlier studies in that several of the au-

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Table II. Findings from surveys of edentulous patients since publication of FDA/ADA guideline Categories in Common to All Studies*

Authors Axelsson 1988 (Iceland) 12 Dias and Jiffry 1988 (Malaysia) 11 Edgerton and Clark 1991 (U.S.) t4 Seals et al. 1992 (U.S.) 15 Soikkonen et al. 1994 (Finland)t 3

Unerupted Foreign teeth [bodies I Radiopacities

Number of subjects

Percentage of subjects with findings

Total number of findings

Root tip

225

22

59

55

19

488

20

135

49

308

23

97

448

12

124

29

(%)

Radiolucencies

(%)

(%)

2

13

10

9

7

24

11

25

10

n/a

56

9

52

10

29

33

29

rda

40

35

13

rda

40

13

*Most studies also listed anatomic variants, lymph node calcifications, and sinus changes to varying degrees.

thors provided more precise interpretations of their radiographic observations. For example, Dias and Jiffry 11 reported the 32 radiopacities as symptomless areas of sclerosis. Axelsson 12 and Soikkonen et al. 13 reported 8 and 16 radiopacities, respectively, but identified only one case of condensing osteitis in each study; there was no indication whether either patient had symptoms. Although they reported substantial numbers of radiopacities, neither Edgerton et al. 14 nor Seals et al. 15 indicated whether any of these had pathologic significance. The findings, with respect to root tips, in Table II are similar to the pre-1988 studies in that the U.S. study populations yielded substantially lower percentages than the populations in the other studies. Nonetheless, the authors of the studies listed in Table II reaffirmed the FDA panel's conclusion that screening radiography is appropriate for the new edentulous patient. As in the earlier studies, their opinion was based on the percentage of radiographic observations regardless of their significance. ANALYSIS OF STUDIES WHEN TREATMENT IMPACT WAS ASSESSED In addition to the studies that simply reported all the radiographic findings as shown in Tables I and II, a small number of studies published in the same period indicated the treatment impact of the radiographic findings (Table III). Two of the five studies 16, 17 reported only those findings that had an impact on treatment; whereas the remaining three 18-2° listed all the radiographic findings in the traditional way but identified those that had significance in terms of patient management. Although the number of root tips, unerupted teeth, foreign bodies, radiopacities, and radiolucencies were similar to those shown in Tables I and II, only a small number of patients had findings

Table III. Studies of occult radiographic findings when treatment impact was determined

White et al* 1984 (U.S.) 16 Lloyd and Gambert 1984 (U.S.) 18 Garcia et al. 1987 (U.S.) 19 Lyman and Boucher* 1990 (U.S.) 17 Kogon et al. 1991 (Canada) 2°

Number of sub]ects

Subjects with findings

Subjects when findings had treatment impact

in)

(%)

(%)

117

7

7*

74

9

0

33

39

6?

150

1

1

51

33

2

*The eight radiographic findings reported included planned surgery (2), mandibular atrophy (3) and "rule out subcondylar fracture" (I). tTreatment was recommended for two patients each of whom had one root tip. The patients did not follow the recommendation. The radiographic appearance of the abnormality remained stable over the 10 year study period.

that required treatment. Not surprisingly, all of the authors concluded that the use of an initial baseline panoramic or periapical survey provided very limited information that affected treatment. As White et al. 16 noted, for both the dentate and the edentulous patient there is only a slight probability of detecting significant conditions with screening panoramic radiographs. However, when radiographs are taken selectively, the yield of treatable abnormalities is high. Garcia et al. 19 reported that " N o change was noted over time in the radiographic findings observed during the initial, or baseline panoramic examination, and no new radiographic findings occurred over the 10-year longitudinal study period." The study by Kogon et al. 2° examined the efficacy of using selection criteria to determine which patients required di-

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May 1997 agnostic radiographs; 14% of the patients required selective radiographs and these produced the only treatable abnormalities.

DISCUSSION Our analysis indicates that imprecision in the definition of abnormality, lack of an assessment of treatment impact, and differences in the populations studied must bring into question the validity of the recommendation of screening radiography for new edentulous patients. According to Fletcher et al.,21 " T h e point of distinguishing normal from abnormal is to separate out those observations that should be considered for action from those that can be discounted." None of the articles cited by the FDA panel (Table I) distinguished between those findings that would have an impact on treatment from those that were of no consequence. In clinical epidemiology, abnormality can range from the "statistically unusual" to those observations that are regularly associated with disease, regardless of frequency. Further, in clinical practice, those conditions that are asymptomatic and are expected to remain so should not be considered abnormal. 21 This approach avoids describing statistically unusual but harmless findings as "pathologic conditions" or "lesions." When the studies cited by the panel are analyzed, an overwhelming majority of the findings such as amalgam scrap, sclerotic bone patches, retention cysts in the sinus, elongated styloid processes, unerupted teeth without pathology, and calcified lymph nodes are not abnormalities that require treatment. When the radiographic observations are limited to treatable abnormalities, all except root fragments are seen in such small numbers as to be of little consequence in epidemiologic terms. 16-20 Even root fragments, unless there is associated pathologic change or they are located on or near the surface of the alveolar process, would be retained to preserve the integrity of the edentulous ridges. 22 Because the majority of the reported findings were abnormalities only in statistical terms, the conclusions reached by the authors and the expert panel that the high level of "pathologic findings" justified the recommendation of screening radiography is not well-founded. If screening radiography is to be recommended for edentulous patients, it should be based on evidence of disclosure of a significant number of treatable findings or evidence that treatment would be required some time in the future. The accepted method of developing evidence= based clinical guidelines establishes a direct relationship between the validity of the recommendation and the strength of the scientific evidence that is used to support it. 4 We have shown that for new edentulous

patients, the FDA guideline that recommended screening radiography was based on studies that did not assess the impact on treatment of the reported findings and therefore provided insufficient scientific support for the recommendation. Further, the cited literature reveals significant differences in the populations studied, Although a recommendation for screening radiography could be justified in specific populations with a high percentage of treatable findings, such a recommendation does not have universal application. It is important to note that in rejecting screening radiography for recall edentulous patients, the panel cited a U.S. study 18 in which the authors assessed their findings in terms of "treatable abnormalities." It is clear from studies published since 1988 that when impact on treatment is considered, the efficacy of screening radiography is minimal. From an epidemiologic point of view, an initial radiographic survey of edentulous patients fails to meet many of the fundamental tenets of a screening program. 23 The lack of a strong scientific basis for the current recommendation and a recently reported finding that 47% of general dentists are currently prescribing selective radiographs for new edentulous patients, 24 indicates the need for a reappraisal of the guideline by the FDA and ADA. Finally, we would suggest that in the absence of unequivocal scientific evidence to support the current recommendation of an initial radiographic survey for the new edentulous patient, practitioners may use the principle of selective radiography to prescribe radiographs, basing their judgment on clinical diagnostic need. The management for these patients would then be consistent with that recommended for all other categories. REFERENCES

1. Councilon Dental Research, Councilon Dental Materials and Devices. Radiation hygiene and practice in dentistry. J Am Dent Assoc 1967;74:1032-3. 2. Council on Dental Materials, Instruments, and Equipment. Recommendations in radiographic practices. J Am Dent Assoc 1981;103:103-4. 3. United States Department of Health and Human Services Public Health Service, Food and Drug Administration. The selection of patients for x-ray examinations: dental radiographic examinations. Rockville, MD: HHS PublicationFDA 88-8273, 1987:12-3. 4. Leape LL. Practice guidelines and standards: an overview. QRB (Feb.) 1990;16:42-9. 5. United States Department of Health and Human Services Public Health Service, Food and Drug Administration. The selection of patients for x-ray examinations: dental radiographic examinations. Rockville,MD: HHS PublicationFDA 88-8273, 1987:16. 6. Jones JD, Seals RR, Schelb E. Panoramic radiographic examinaton of edentulous patients. J Prosthet Dent 1985; 53:535-9. 7. Perrelet LA, Bernhard M, Spirgi M. Panoramic radiography

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in the examination of edentulous patients. J Prosthet Dent 1977;37:494-8. Spyroponlos ND, Patsakas A J, Angelopoulos AP. Findings from radiographs of the jaws of edentulous patients. Oral Surg Oral Med Oral Pathol 1981;52:455-9. Keur JJ, Campbell JPS, McCarthy JF, et al. Radiological findings in 1,135 edentulous patients. J Oral Rehab 1987; 14:183-91. Keur JJ. Radiographic screening of edentulous patients: sense or nonsense? a risk-benefit analysis. Oral Surg Oral Med Oral Pathol 1986;62:463-7. Dias AP, Jiffry MTM. Orthopantomographic survey of edentulous patients and different age groups in Malaysia. Austral Dent Jonr 1988;33:23-6. Axelsson G. Orthopantomographic examination of the edentalons mouth. J Prosthet Dent 1988;59:592-8. Soikkonen K, Ainamo A, Wolf J, et al. Radiographic findings in the jaws of clinically edentulous old people living at home in Helsinki, Finland. Acta Odontol Scand 1994;52:22933. Edgerton M, Clark P. Location of abnormalities in panoramic radiographs of edentulous patients. Oral Surg Oral Med Oral Pathol 1991;71:106-9. Seals RR, Williams EO, Jones JD. Panoramic radiographs: necessary for edentulous patients? J Am Dent Assoc 1992; 123:74-8. White SC, Forsythe AB, Joseph LP. Patient-selection criteria for panoramic radiography. Oral Surg Oral Med Oral Pathol 1984;57:681-90.

17. Lyman S, Boucher LJ. Radiographic examination of edentulous mouths. J Prosthet Dent 1990;64:180-2. 18. Lloyd PM, Gambert SR. Periodic oral examinations and panoramic radiographs in edentulous elderly men. Oral Surg Oral Med Oral Pathol 1984;57:678-80. 19. Garcia RI, Valachovic RW, Chauncey HH. Longitudinal study of the diagnostic yield of panoramic radiographs in aging edenmlous men. Oral Surg Oral Med Oral Pathol 1987; 63:494-7. 20. Kogon SL, Charles DH~ Stephens RG. A clinical study of radiographic selection criteria for edentulous patients. J Can Dent Assoc 1991;57:794-8. 21. Fletcher RH, Fletcher SW, Wagner EH. Clinical epidemiology, the essentials. 2nd ed. Baltimore: Williams and Wilkins, 1988:19-41. 22. Garver DG, Fenster RK. Vital root retention in humans: a final report. J Prosthet Dent 1980;43:368-73. 23. Mausner JS, Kramer S. Epidemiology: an introductory text. 2nd ed. Philadelphia: Saunders 1985:228-9. 24. Kogon SL, Bohay RN, Stephens RG. A survey of the radiographic practices of general dentists for edentulous patients. Oral Surg Oral Med Oral Pathol Oral Radiol Endod 1995; 80:365-8.

Reprint requests: Dr. S.L. Kogon University of Western Ontario Faculty of Dentistry London, Ontario, Canada N6G 1P2

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A separate and distinct space for Letters to the Editor was established by Larry J. Peterson, editor in chief of Oral Surgery, Oral Medicine, Oral Pathology, Oral Radiology, and Endodontics in his Editorial in the January 1993 issue. Dr. Peterson also encouraged brief reports on interesting observations and new developments to be submitted to appear in this letters section as well as Letters commenting on earlier published articles. Please submit your letters and brief reports for inclusion in this section. Information for authors for the Journal appears in this issue of Oral Surgery, Oral Medicine, Oral Pathology, Oral Radiology, and

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