Advantages and disadvantages of the use of dental tomographic radiography
C o u ncil on D e n ta l M a te ria ls and D e v i c e s H i H H
In recent years, the use of tomographic radiog raphy in dentistry has increased at a very rapid rate. (Tomographic is used instead of panoramic because panoramic includes tomographic tech niques and intraoral source techniques.) Because of this growing use and a concern for unneces sary exposure to ionizing radiation, the Council on Dental Materials and D evices believes guide lines on the proper use of tomographs are appro priate. These guidelines are intended for current ly available dental X-ray equipment that oper ates on the principles of curved surface tomog raphy. Although tomographs can be very useful in particular situations, discretion is necessary in the selection o f cases. Tomographs present greater area coverage and exposure than do conventional intraoral radiographs. Because o f magnification, lack of detail, and superimposition of structures, how ever, tomographs may be diagnostically inferior to intraoral radiographs. Tomographic radiog raphy and intraoral radiography are different procedures and cannot be precisely compared. The selection of the procedure to be used de pends on the diagnostic requirements of the in dividual patient.
Advantages — It is a simple procedure to perform. — It is convenient for the patient. — It can be used in patients with intractable gagging problems. — The time required for the procedure is min imal. — Those portions o f the maxilla and mandible lying within the focal trough o f the machine can be visualized on a single film. —The patient dose is relatively low but not negligible.
—Tomographs taken for diagnostic purposes also can be useful as a visual aid in patient edu cation.
Disadvantages —Areas of diagnostic interest out of the focal trough may be visualized poorly or not at all. —Tomographs inherently show magnifica tion, geometric distortion, and poor definition. — Overlapping of the teeth commonly occurs, particularly in the bicuspid area. —The anterior teeth register poorly when they have pronounced inclinations. —The spinal column may interfere with the production of the radiograph. —The amount o f vertical and horizontal dis tortion varies from one part of the film to an other. —The ease and convenience of obtaining a tomograph may encourage careless evaluation of a patient’s specific radiographic needs. — Artifacts are easily misinterpreted. The tomographic survey can be very valuable to the dentist in the evaluation of patients. The relatively large volume of tissue necessarily ir radiated by tomographic radiography suggests that this technique should not be used indiscrim inately. When specific information that is best provided by tomography is required, the use of this technique can be justified. Tomography should be considered as a supplement to the di agnostic radiology procedure, and should not be considered as a substitute for a good clinical examination and conventional intraoral radiog raphy. This report was prepared for the Council on Dental Materials and Devices by the Radiation Protection Committee of the Amer ican Academy of Dental Radiology. The committee members are O. N. Johnson, chairman; R. W. Alcox; L. R. Bean; A. B. Reiskin; A. G. Richards; and S. C. White.
REPORTS OF COUNCILS AND BUREAUS / JADA, Vol. 94, January 1977 ■ 147
C o u ncil on D e n ta l M a te ria ls and D e v i c e s H i H H
In recent years, the use of tomographic radiog raphy in dentistry has increased at a very rapid rate. (Tomographic is used instead of panoramic because panoramic includes tomographic tech niques and intraoral source techniques.) Because of this growing use and a concern for unneces sary exposure to ionizing radiation, the Council on Dental Materials and D evices believes guide lines on the proper use of tomographs are appro priate. These guidelines are intended for current ly available dental X-ray equipment that oper ates on the principles of curved surface tomog raphy. Although tomographs can be very useful in particular situations, discretion is necessary in the selection o f cases. Tomographs present greater area coverage and exposure than do conventional intraoral radiographs. Because o f magnification, lack of detail, and superimposition of structures, how ever, tomographs may be diagnostically inferior to intraoral radiographs. Tomographic radiog raphy and intraoral radiography are different procedures and cannot be precisely compared. The selection of the procedure to be used de pends on the diagnostic requirements of the in dividual patient.
Advantages — It is a simple procedure to perform. — It is convenient for the patient. — It can be used in patients with intractable gagging problems. — The time required for the procedure is min imal. — Those portions o f the maxilla and mandible lying within the focal trough o f the machine can be visualized on a single film. —The patient dose is relatively low but not negligible.
—Tomographs taken for diagnostic purposes also can be useful as a visual aid in patient edu cation.
Disadvantages —Areas of diagnostic interest out of the focal trough may be visualized poorly or not at all. —Tomographs inherently show magnifica tion, geometric distortion, and poor definition. — Overlapping of the teeth commonly occurs, particularly in the bicuspid area. —The anterior teeth register poorly when they have pronounced inclinations. —The spinal column may interfere with the production of the radiograph. —The amount o f vertical and horizontal dis tortion varies from one part of the film to an other. —The ease and convenience of obtaining a tomograph may encourage careless evaluation of a patient’s specific radiographic needs. — Artifacts are easily misinterpreted. The tomographic survey can be very valuable to the dentist in the evaluation of patients. The relatively large volume of tissue necessarily ir radiated by tomographic radiography suggests that this technique should not be used indiscrim inately. When specific information that is best provided by tomography is required, the use of this technique can be justified. Tomography should be considered as a supplement to the di agnostic radiology procedure, and should not be considered as a substitute for a good clinical examination and conventional intraoral radiog raphy. This report was prepared for the Council on Dental Materials and Devices by the Radiation Protection Committee of the Amer ican Academy of Dental Radiology. The committee members are O. N. Johnson, chairman; R. W. Alcox; L. R. Bean; A. B. Reiskin; A. G. Richards; and S. C. White.
REPORTS OF COUNCILS AND BUREAUS / JADA, Vol. 94, January 1977 ■ 147
