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The radiographic examination of edentulous patients
The radiographic
examination
of edentulous
patients
Susan M. Wright, M.D.!& F.D.S.R.C.S. (Eng)* Royal Dental Hospital of London, School of Dental Surgery, London, England
R
adiographic examination of edentulous patients is advisable prior to the construction of dentures. Such an examination will often reveal the presence of residual roots, unerupted teeth, or other abnormalities in patients who are otherwise free from signs or symptoms that might suggest the existence of a pathologic condition.‘-’
USE OF THE ORTHOPANTOMOGRAPH FOR ROUTINE EXAMINATION’ OF PROSTHETIC PATIENTS Orthopantomography has proved very useful for carrying out a rapid radiologic survey and has been used in many studies on both dentate and edentulous subjects.5-7 The panoramic tomographic radiograph can be regarded as a composite made up of a large number of narrow slitlike exposures. The tube and film of the orthopantomograph are linked together in a constant relationship and moved around the patient, turning around three centers of rotation. The structures under investigation lie in a set image layer. All other structures, being outside this layer, ideally are not recorded. The images of the maxillae and mandible and associated structures are considerably magnified, but distortion is comparatively low as the incident rays are at right angles to the structures concerned.8 Although the orthopantomogram shows limited bone detail, it allows for elective and rational use of supplementary periapical films. This means a lower patient irradiation dose and a saving in time compared to a full mouth survey by means of intraoral periapical radiographs.
LIMITATIONS OF THE ORTHOPANTOMOGRAPH Interpretation of a radiograph depends on accurate knowledge of the normal anatomy of the region and anticipation of the anatomic and other structures that lie beyond the part being investigated. The shadows of these structures, when superimposed on the main picture, may give rise to misleading appearances. *Senior Lecturer, Department of Prosthetic Dentistry.
164
The use of the orthopantomograph machine in a routine survey is satisfactory, provided that the inherent distortions in ‘the radiographs it produces are recognized and taken into consideration. The anterior region in particular cannot be relied on to present a true picture (Fig. l).” The superimposed shadows of the cervical spine may confuse interpretation of the orthopantomogram. The cervical vertebrae produce three shadows. The lateral ones are associated with the two posterior centers of rotation. The midline shadow, produced during scanning from the anterior center, is the most distorted and least clear because of the relatively greater distance from the image layer.’ In the premolar region a variable and sometimes considerable distortion occurs as the region is recorded at the periphery of the fields of two of the centers of rotation.8 In consequence, existing pathoses such as unerupted teeth may be masked (Fig. 2). Variable shadows are produced when objects lie outside the image layer of the orthopantomogram. This increases the problem of their identification. The depth of focus of the image layer is about 15 mm in the molar region and considerably less anteriorly.’ Only that part of a buried tooth that is within the tomographic image layer produces a clear, well-defined image with relatively low distortion. The usual position of a buried upper premolar, for example, is with its crown pointing palatally’O (Fig. 3) so that much of AUGUST
1983
VOLUME
50
NUMBER
2
RADIOGRAPhIC
EXAMINATION
Fig. 2. Orthopantomogram upper premolar.
OF EDENTULOUS
showing
Fig. 3. Lateral skull radiograph tooth buried in maxilla.
PATIENTS
part of buried
showing
premolar
Fig. 4. Upper anterior occlusal radiograph showing buried upper canine lying within edentulous ridge.
Fig. 5. Upper oblique occlusal premolar lying across arch.
radiograph
showing
the tooth will .not be in focus on an orthopantomogram. Further confusion may arise from superimposed shadows of othler nonanatomic structures, such as earrings.6, R,’
In addition to the orthopantomogram, the routine use of an upper standard occlusal film in the radiologic investigation of edentulous patients would prevent the overlooking of pathologic changes in the anterior and premolar regions of the maxillae (Figs. 4 and 5).
AVOIDANCE
CONCLUSION
OF MISDIAGNOSIS
When radiographic distortions occur, the presence of an existing pathology will be masked; and if there are no clear intraoral signs or symptoms to indicate its presence, it is unlikely that further radiographic views will be requested. Consequently, the pathosis will remain undiagnosed. THE JOURNAL
OF F’ROSTHETIC
DENTISTRY
Routine radiographic
examination
patients prior to the construction
of edentulous
of dentures is advis-
able. This may be readily carried out by means of an orthopantomograph machine. The unreliability of the radiographic appearance of the anterior and premolar regions of the orthopantomogram indicates the need for 165
WRIGHT
supplementary radiograph.
use of an upper standard occlusal
6.
7.
I am grateful to Mr. W. E. G. White of the Royal Dental Hospital of London, School of Dental Surgery, for the photographs.
REFERENCES 1. Storer, R.: A radiographic survey of edentulous mouths. Br Dent J 103:344, 1957. 2. Coy, W. A., and Kenneth, R. W.: A roentgenographic examination of fully edentulous patients. Dent Digest 72:200, 1966. 3. Michaeli, Y., Hermel, J., Gizenfeld, E., and Michman, J.: Pathologic radiographic findings in clinically symptom-free edentulous subjects. Oral Surg 26:27, 1968. 4. Barclay, J. K., and Donaldson, K. I.: Panoramic radiography of the edentulous. A survey of 100 patients. NZ Dent J 66:53, 1970. 5. Bremner, V. A., and Grant, A. A.: A radiographic survey of edentulous mouths. Aust Dent J 16:17, 1971.
166
8. 9. 10.
Keith, D. A.: The detection of abnormalities in the jaws. Br Dent J 134~129, 1973. Perrelet, L. A., Bernhard, M., and Spirgi, M.: Panoramic radiography in the examination of edentulous patients. J PROSTHETDENT 37:494, 1977. Rowe, C. W.: Notes on interpretation of the orthopantomogram. Br Dent Jr 130:425, 1971. Edge, M. B. B., and Champion, C.: Interpretation of the orthopantomogram. Br Dent J 133~289, 1972. Killey, H. C., Seward, G. R., and Kay, L. W.: An Outline of Oral Surgery, ed 1 (revised reprint). Bristol, 1971, John Wright & Sons, Ltd., part 1, p 40.
Rep& requests to: MISS SUSAN M. WRIGHT KING’S COLLEGEHOSPITAL MEDICAL SCHOOL DENTAL SCHOOL DENMARK
HILL
LONDON SE5 8RX ENGLAND
AUGUST
1983
VOLUME
50
NUMBER
2
examination
of edentulous
patients
Susan M. Wright, M.D.!& F.D.S.R.C.S. (Eng)* Royal Dental Hospital of London, School of Dental Surgery, London, England
R
adiographic examination of edentulous patients is advisable prior to the construction of dentures. Such an examination will often reveal the presence of residual roots, unerupted teeth, or other abnormalities in patients who are otherwise free from signs or symptoms that might suggest the existence of a pathologic condition.‘-’
USE OF THE ORTHOPANTOMOGRAPH FOR ROUTINE EXAMINATION’ OF PROSTHETIC PATIENTS Orthopantomography has proved very useful for carrying out a rapid radiologic survey and has been used in many studies on both dentate and edentulous subjects.5-7 The panoramic tomographic radiograph can be regarded as a composite made up of a large number of narrow slitlike exposures. The tube and film of the orthopantomograph are linked together in a constant relationship and moved around the patient, turning around three centers of rotation. The structures under investigation lie in a set image layer. All other structures, being outside this layer, ideally are not recorded. The images of the maxillae and mandible and associated structures are considerably magnified, but distortion is comparatively low as the incident rays are at right angles to the structures concerned.8 Although the orthopantomogram shows limited bone detail, it allows for elective and rational use of supplementary periapical films. This means a lower patient irradiation dose and a saving in time compared to a full mouth survey by means of intraoral periapical radiographs.
LIMITATIONS OF THE ORTHOPANTOMOGRAPH Interpretation of a radiograph depends on accurate knowledge of the normal anatomy of the region and anticipation of the anatomic and other structures that lie beyond the part being investigated. The shadows of these structures, when superimposed on the main picture, may give rise to misleading appearances. *Senior Lecturer, Department of Prosthetic Dentistry.
164
The use of the orthopantomograph machine in a routine survey is satisfactory, provided that the inherent distortions in ‘the radiographs it produces are recognized and taken into consideration. The anterior region in particular cannot be relied on to present a true picture (Fig. l).” The superimposed shadows of the cervical spine may confuse interpretation of the orthopantomogram. The cervical vertebrae produce three shadows. The lateral ones are associated with the two posterior centers of rotation. The midline shadow, produced during scanning from the anterior center, is the most distorted and least clear because of the relatively greater distance from the image layer.’ In the premolar region a variable and sometimes considerable distortion occurs as the region is recorded at the periphery of the fields of two of the centers of rotation.8 In consequence, existing pathoses such as unerupted teeth may be masked (Fig. 2). Variable shadows are produced when objects lie outside the image layer of the orthopantomogram. This increases the problem of their identification. The depth of focus of the image layer is about 15 mm in the molar region and considerably less anteriorly.’ Only that part of a buried tooth that is within the tomographic image layer produces a clear, well-defined image with relatively low distortion. The usual position of a buried upper premolar, for example, is with its crown pointing palatally’O (Fig. 3) so that much of AUGUST
1983
VOLUME
50
NUMBER
2
RADIOGRAPhIC
EXAMINATION
Fig. 2. Orthopantomogram upper premolar.
OF EDENTULOUS
showing
Fig. 3. Lateral skull radiograph tooth buried in maxilla.
PATIENTS
part of buried
showing
premolar
Fig. 4. Upper anterior occlusal radiograph showing buried upper canine lying within edentulous ridge.
Fig. 5. Upper oblique occlusal premolar lying across arch.
radiograph
showing
the tooth will .not be in focus on an orthopantomogram. Further confusion may arise from superimposed shadows of othler nonanatomic structures, such as earrings.6, R,’
In addition to the orthopantomogram, the routine use of an upper standard occlusal film in the radiologic investigation of edentulous patients would prevent the overlooking of pathologic changes in the anterior and premolar regions of the maxillae (Figs. 4 and 5).
AVOIDANCE
CONCLUSION
OF MISDIAGNOSIS
When radiographic distortions occur, the presence of an existing pathology will be masked; and if there are no clear intraoral signs or symptoms to indicate its presence, it is unlikely that further radiographic views will be requested. Consequently, the pathosis will remain undiagnosed. THE JOURNAL
OF F’ROSTHETIC
DENTISTRY
Routine radiographic
examination
patients prior to the construction
of edentulous
of dentures is advis-
able. This may be readily carried out by means of an orthopantomograph machine. The unreliability of the radiographic appearance of the anterior and premolar regions of the orthopantomogram indicates the need for 165
WRIGHT
supplementary radiograph.
use of an upper standard occlusal
6.
7.
I am grateful to Mr. W. E. G. White of the Royal Dental Hospital of London, School of Dental Surgery, for the photographs.
REFERENCES 1. Storer, R.: A radiographic survey of edentulous mouths. Br Dent J 103:344, 1957. 2. Coy, W. A., and Kenneth, R. W.: A roentgenographic examination of fully edentulous patients. Dent Digest 72:200, 1966. 3. Michaeli, Y., Hermel, J., Gizenfeld, E., and Michman, J.: Pathologic radiographic findings in clinically symptom-free edentulous subjects. Oral Surg 26:27, 1968. 4. Barclay, J. K., and Donaldson, K. I.: Panoramic radiography of the edentulous. A survey of 100 patients. NZ Dent J 66:53, 1970. 5. Bremner, V. A., and Grant, A. A.: A radiographic survey of edentulous mouths. Aust Dent J 16:17, 1971.
166
8. 9. 10.
Keith, D. A.: The detection of abnormalities in the jaws. Br Dent J 134~129, 1973. Perrelet, L. A., Bernhard, M., and Spirgi, M.: Panoramic radiography in the examination of edentulous patients. J PROSTHETDENT 37:494, 1977. Rowe, C. W.: Notes on interpretation of the orthopantomogram. Br Dent Jr 130:425, 1971. Edge, M. B. B., and Champion, C.: Interpretation of the orthopantomogram. Br Dent J 133~289, 1972. Killey, H. C., Seward, G. R., and Kay, L. W.: An Outline of Oral Surgery, ed 1 (revised reprint). Bristol, 1971, John Wright & Sons, Ltd., part 1, p 40.
Rep& requests to: MISS SUSAN M. WRIGHT KING’S COLLEGEHOSPITAL MEDICAL SCHOOL DENTAL SCHOOL DENMARK
HILL
LONDON SE5 8RX ENGLAND
AUGUST
1983
VOLUME
50
NUMBER
2