- Email: [email protected]
Xeroradiography of dental structures. III. Pilot clinical studies
Xeroradiography of dental structures. III. Pilot clinical studies Barton M. Gratt, D.D.S., DIVISION OF GENERAL
* San Francisco,
DENTISTRY.
Cali’.
UNIVERSITY
OF CALIFORNIA
SCHOOL OF DENTISTRY
A new experimental intraoral dental xeroradiographic system was evaluated for future application in dentistry. Similar projections on conventional film radiographs and experimental dental xeroradiographs were compared visually and radiation exposure for both techniques was measured by thermoluminescent dosimetry. The xeroradiographic system was judged superior for imaging most structures, especially oral soft tissues, subtle bony abnormalities, and fine calculus deposits. Furthermore, xeroradiography requires only one third the radiation exposure of corresponding conventional film techniques. Dental xeroradiography appears to have great promise in radiographic interpretation of oral disease.
X
eroradiography uses the xerographic copying process to record images produced by diagnostic x-rays. It differs from conventional film recording systems by involving neither wet chemical processing nor the use of a darkroom. Instead of conventional silver halide x-ray film, xeroradiography uses a uniformly charged selenium-alloy photoreceptor plate, held in a lightproof cassette. When exposed to x-rays, the charge on the photoreceptor is partially dissipated, forming a latent electrostatic image. This latent image is transferred into a real image by the use of pigmented particles permanently heat-sealed onto a base sheet. The resultant image is usually viewed by reflected (overhead) light, although it may be examined by transilluminated light from a viewbox. The entire technique is fast. requiring 90 seconds to produce a final image. It is also economical because the photoreceptor plates are reconditioned, recharged, and used repeatedly. Xeroradiography produces pictures with greater latitude of exposure than conventional techniques by being able to portray the full range of oral tissue densities; metallic restorations, bone, and soft tissues all are successfully portrayed in a single image. In addition. xeroradiographic pictures benefit from the property of “edge enhancement, ” by which small structures (e.g.. bone trabeculae) and areas of subtle density differences (e.g., gingival tissues) are made more visible. In preliminary investigations, we applied the Xerox This study UZISsupported in part by funds from Biomedical Research Support Grant RR-05305 17 (78439-29681-3). *Assistant Professor. Oral Radiology.
276
Table 1. Comparative visual analysis of intraoral radiographic anatomy
structure Bone Gross bony abnormalities Fine bony abnormalities Trabecular pattern Periodontal ligament space Soft Tissue Gingival tissues Superimposed structures (e.g., nose, cheeks) Minor calcifications Lacerations Hyperplastic changes about prostheses Teeth Dental morphology (crown and roots) Pulpal chambers, horns, canals Composite restorations/ pontics Severe caries Early caries Recurrent caries (under metallic restorations) Recurrent caries (under composite restorations) Gross dental calculus Fine dental calculus S&e: +++ = Optimal; ++ nostic; 0 = Unacceptable. 0030.4220/79/090276+05$00.50/0
Conventional film technique
+++
Experimental dental xeroradiographic technique
+ ++ f-t
++ +++ ii+ ii+
0 +
++ +++
0 0 0
+++ ++ ii
++
+++
++
+++
++
+++
+++
+++ ++ 0
+ +++ ++
+++
++ 0
+++ +++
= Adequate; + = Poor but diag-
0
1979
The C. V. Mosby Co.
Volume 48 3
Xeroradiography
of dental structures.
III
Fig. 1. Top /
277
270
Gratt
OFdSUrg. September, 1979
Fig. 2. Left, Molar bitewing xeroradiograph demonstrating excellent visualization of teeth. metallic restorations, bone, and soft tissue structures. Note improved diagnostic imaging of gingival soft tissues covering crestal alveolar bone, and clear imaging of the cardboard bitewing tab and other oral and extraoral soft tissue structures and densities absent in conventional bitewing films (~hirc~ uro\\.s). Right, Similarly projected conventional bitewing film. Note the clear boundaries between metallic restorations and normal regions of dentin and enamel. signifying the absence of caries. The xeroradiographic image demonstrates minor edge deletion artifacts in these locations, not to be confused with recurrent caries (black arrows). Table II. Clinical radiation dosimetry measurements
Technique
Conventional film radiography Experimental dental xeroradiography
Entrance skin dose per exposure (mR)
Exit dose (at imaging detector) per exposure (mR)
204 (Range 180-230, S.D. 2 12.3, n = 27) 70 (Range 50-80, S.D. k 7.7, n = 27)
119 (Range 90-150, S.D. k 16.9, n = 27) 40 (Range 20-60, S.D. i 9.6, n = 27)
125 Medical System (Xerox Corp., Pasadena, Calif.) to imaging dental structures in vitro. We demonstrated that conventional dental x-ray units are an excellent source of radiation for xeroradiography. Futhermore, we produced high-quality xeroradiographic images of teeth, restorations, bone, and soft tissues, at radiation doses seven to fourteen times less than with conventional intraoral film radiography. ’ Qualitative and quantitative comparison of the resolution, noise, and contrast of images produced by xeroradiography and conventional intraoral film radiography showed only minor differences between the two techniques despite the reduced radiation dose with xeroradiography. Furthermore, the greater latitude of xeroradiography and its property of edge enhancement permitted superior visualization of soft tissues, composite restorations, endodontic filling materials, acrylic pontics, dental calculus, plastic crowns, and denture bases not seen well on conventional film images.’ Recently the Xerox Corporation developed a pro-
totype dental xeroradiographic system designed specifically for intraoral use, a significant step forward from the Xerox 12.5Medical System that we used previously, which could be evaluated only in the laboratory. This new imaging system is appropriately scaled down in size for intraoral radiography. It uses a black toner rather than blue plastic particles to form the visible radiographic image. These changes, among others, promise to increase the quality of dental radiographic images substantially while still permitting a sizeable reduction in radiation dose from that of conventional intraoral film radiography. The present pilot study is a preliminary in vivo evaluation of the prototype dental xeroradiographic system and assessesits potential applications in dentistry. MATERIALS
AND METHODS
The source of x-radiation for both conventional radiography and xeroradiography was a dental x-ray unit having a nominal focal spot size of 1.0 mm. and total filtration of 2.5 mm. aluminum (General Electric 100, General Electric Co.. Milwaukee, Wis.). All radiographs were taken at a target-film distance of at least 16 inches (41 cm.). using 75 to 100 kVp., IO mA., and a beam diameter of 2.75 inches (7 cm.). Average exposure times were ‘1’2second (30 impulses) for conventional film radiography and ‘/6 second (10 impulses) for dental xeroradiography. Conventional film images were recorded on Kodak D speed periapical film. DF-57 and DF-55, paperwrapped double film packets. They were developed at 70” F. (21” C.) for 4% minutes in Kodak Dental Liquid X-ray Developer (Eastman Kodak Co., Rochester,
Volume Number
48 3
N. Y), water-rinsed for 15 seconds, fixed at 70” F. (21” C.) for 10 minutes in Kodak Dental Liquid X-ray Fixer, washed for 30 minutes, and air-dried. For intraoral dental xeroradiography, we used the prototype xeroradiography image-processing system and selenium-alloy photoreceptors and cassettes described above. The prototype system charges a photoreceptor and inserts it into a lightproof cassette. After being placed in a disposable sterile plastic bag, positioned, and exposed in a patient’s mouth, the cassette is reinserted into the prototype system for development. The system produces a xeroradiographic picture in 20 seconds. The used photoreceptor is then reconditioned and may be reused repeatedly. This prototype system worked without fail, producing over 1,000 clinical dental xeroradiographs. Film packets and dental xeroradiography cassettes were positioned intraorally by conventional positioning devices now in use at the University of California, School of Dentistry (bitewing tabs, wood-block film holders, and a Fitzgerald x-ray filmholding unit). These positioning devices were easily adjusted to the greater thickness of the xeroradiography cassettes. Radiation exposure was measured on nine randomly selected patients, using lithium fluoride thermoluminescent dosimeters (Radiation Detection Co., Sunnyvale, Calif.) placed at the skin surface (over the mandibular first molar) within the area of the primary beam. These dosimetric measurements are accurate to ? 10 mR. for values below 100 mR. and to ~fr10 percent for values above 100 mR. Fifty volunteer dental patients requiring complete mouth x-ray examination (twenty to twenty-six projections) for routine dental treatment were x-rayed using conventional film techniques. Then a selected side (based on the presence of dental or oral pathology) was xeroradiographed. We positioned intraoral xeroradiography cassettes in a manner similar to the film packets positioning, attempting to produce the same projections with both techniques. Resultant images were than visually evaluated for diagnostic quality. The appearance of eighteen selected anatomic structures was judged as either optimal (+ + +), adequate (+ +), poor but diagnostic (+), or unacceptable (0). This method has been used in other investigations to evaluate diagnostic radiographic quality.“-” RESULTS
Clinical evaluations were made on 550 pairs of conventional film vs. xeroradiographic images. Table I presents the results of the analysis of anatomic structure visibility. Experimental dental xeroradiography was judged to be superior for the imaging of (1) dental anatomy, (2) fine bony detail (3) all soft tissue struc-
Xerorudiography
of dental
structures.
Ill
279
tures, (4) early and moderate dental caries, and (5) fine deposits of calculus. Conventional film technique was judged superior for imaging large, broad areas, such as when evaluating the overall radiodensity of the maxillary sinus, and also for detecting recurrent dental caries occurring under metallic (but not composite) restorations. Fig. 1 illustrates representative cases. Table II presents the results of dosimetry measurements. The radiation dose of dental xeroradiography was found to be one-third that of the conventional intraoral film technique. DISCUSSION
The new xeroradiographic images appear to be diagnostically superior to conventional film images for detecting tooth, bone, and soft tissue changes because of greater imaging latitude and the unique property of edge enhancement. These two special qualities of xeroradiography permit optimal visualization of both fine bony structures and minute calculus deposits and the clear portrayal of dental caries and many soft tissue structures previously not seen on conventional film radiographs. An added advantage is the threefold reduction in radiation dose of dental xeroradiography. The new dental xeroradiographic equipment, although still in the prototype stage, did demonstrate several features of special convenience. It produced permanent images in only 20 seconds, without the need for a darkroom. It also promises to be more economical than present-day film systems. Compared to conventional film, xeroradiographic supplies are inexpensive. Materials used include plastics, adhesives, and common solvents. The selenium-alloy photoreceptor plates can be reused for at least 1,000 images per plate. Futhermore, the xeroradiographic equipment does not require fixed installation. During our pilot clinical study we easily moved the prototype system to an alternate radiology clinic. Disadvantages observed with the prototype xeroradiographic system were remarkably few. Inappropriate adjustment of processor settings for edge enhancement parameters can create radiolucent shadows termed “edge deletion artifacts.” These radiolucent artifacts appear around sharply defined radiopacities (e.g., metal restorations), giving a false indication of recurrent dental caries (Fig. 2). However, we discovered that excessive edge deletion could be controlled, and that proper adjustment of the processing system and operator experience can readily overcome this problem. An additional difficulty involved the presence of artifacts appearing as spots and lines on 30 percent of the xeroradiographs. While these were distracting, they could readily be identified as artifacts. They probably are caused by dust particles trapped in the hand-built
280
Graft
Oral Surg. September, 1979
protytype unit and may well be eliminated as the design of the processing equipment is further refined. Other investigators recently published an independent evaluation of intraoral xeroradiography involving both a Xerox 125 medical system and the prototype dental system. 6 Their overall conclusion parallels our experience: that the prototype dental system produces images superior in quality to both conventional film and medical xeroradiographic techniques. In summary, our pilot clinical study of a prototype dental xeroradiography unit produced images superior in quality to conventional intraoral film radiography. The entire system appears to be very rapid. economical, and practical. This new imaging system promises to add new dimensions to the diagnosis, treatment, and prevention of dental diseases. I am grateful to Mr. Lothar S. Jeromin and Mr. Glenn P. Geddcs of the Xerox Corp., Pasadena. Calif., for operation of the prototype dental xeroradiographic equipment and to Drs. Troy E. Daniels and Edward A. Sickles, University ot California. Schools of Dentistry and Medicine. for their advice in preparing this manuscript.
INFORMATION
REFERENCES I. Gratt, B. M.. Sickles.
E. A., and Parks, C. R.: Xeroradiography of Dental Structures: 1. Preliminary Investigation\. ORAL SURG. 44: 148-152. 1977. 2. Gratt. B. M Sickles, E. A.. and Parks. C. R.: Xeroradiography of Dental Structure\: II. Imapc Analysis. 0~41 S~IK<,. 46: 1% 16.5. 197X. .-3 Gratt. B. M.. Sickles. E. A.. and Parks. C. R.: Uw of intraoral Cassettes for Dental Xeroradiography. OR.U SLIRG. 46: 7 17-720,
1978. 3. Sickles.
E. A.. Genant. H. K.. and Doi. K.: Comparison of Laboratory and Clinical Evaluations of Mammographic ScreenFilm System\. /)I Application of Optical Instrumentation in Medicine VI. Bellingham, Wash.. 1977, Socxty trf PhotoOptical Inswumentation Engineers. Vol. 127. pp. 30.35. 5. Gratt, B. M.. Parks. C. R.. Hall. G. S., and Sickle\, E. A.: Use of an lnclincd Footrest for lmprovmg Panoramic Dental Radiography.ORAI SURG. 47: 568-571, 1979. 6. White, S. C.. Stafford. M. L., and Beenmga, 1. R.: Intraoral Xcrorndiographg. ORAI SIRG. 46: 862-870, 197X
Rcyrrr~t r~yrtrst.c irk: Dr. Barton M. Gratt UCLA Dental School Center for the Health Science\ Los Angeles. Calif. 90024
FOR AUTHORS
Most of the provisions of the Copyright Act of. 1976 became effective on January I. 1978. Therefore, all manuscripts must be accompanied by the following written statement, signed by one author: “The undersigned author transfers all copyright ownership of the manuscript entitled (title of article) to The C. V. Mosby Company in the event the work is published. The undersigned author warrants that the article is original, is not under consideration by anotherjournal, and has not been previously published, I sign for and accept responsibility for releasingthis material on behalf of any and all co-authors.” Authors will be consulted, when possible, regarding republication of their material.
* San Francisco,
DENTISTRY.
Cali’.
UNIVERSITY
OF CALIFORNIA
SCHOOL OF DENTISTRY
A new experimental intraoral dental xeroradiographic system was evaluated for future application in dentistry. Similar projections on conventional film radiographs and experimental dental xeroradiographs were compared visually and radiation exposure for both techniques was measured by thermoluminescent dosimetry. The xeroradiographic system was judged superior for imaging most structures, especially oral soft tissues, subtle bony abnormalities, and fine calculus deposits. Furthermore, xeroradiography requires only one third the radiation exposure of corresponding conventional film techniques. Dental xeroradiography appears to have great promise in radiographic interpretation of oral disease.
X
eroradiography uses the xerographic copying process to record images produced by diagnostic x-rays. It differs from conventional film recording systems by involving neither wet chemical processing nor the use of a darkroom. Instead of conventional silver halide x-ray film, xeroradiography uses a uniformly charged selenium-alloy photoreceptor plate, held in a lightproof cassette. When exposed to x-rays, the charge on the photoreceptor is partially dissipated, forming a latent electrostatic image. This latent image is transferred into a real image by the use of pigmented particles permanently heat-sealed onto a base sheet. The resultant image is usually viewed by reflected (overhead) light, although it may be examined by transilluminated light from a viewbox. The entire technique is fast. requiring 90 seconds to produce a final image. It is also economical because the photoreceptor plates are reconditioned, recharged, and used repeatedly. Xeroradiography produces pictures with greater latitude of exposure than conventional techniques by being able to portray the full range of oral tissue densities; metallic restorations, bone, and soft tissues all are successfully portrayed in a single image. In addition. xeroradiographic pictures benefit from the property of “edge enhancement, ” by which small structures (e.g.. bone trabeculae) and areas of subtle density differences (e.g., gingival tissues) are made more visible. In preliminary investigations, we applied the Xerox This study UZISsupported in part by funds from Biomedical Research Support Grant RR-05305 17 (78439-29681-3). *Assistant Professor. Oral Radiology.
276
Table 1. Comparative visual analysis of intraoral radiographic anatomy
structure Bone Gross bony abnormalities Fine bony abnormalities Trabecular pattern Periodontal ligament space Soft Tissue Gingival tissues Superimposed structures (e.g., nose, cheeks) Minor calcifications Lacerations Hyperplastic changes about prostheses Teeth Dental morphology (crown and roots) Pulpal chambers, horns, canals Composite restorations/ pontics Severe caries Early caries Recurrent caries (under metallic restorations) Recurrent caries (under composite restorations) Gross dental calculus Fine dental calculus S&e: +++ = Optimal; ++ nostic; 0 = Unacceptable. 0030.4220/79/090276+05$00.50/0
Conventional film technique
+++
Experimental dental xeroradiographic technique
+ ++ f-t
++ +++ ii+ ii+
0 +
++ +++
0 0 0
+++ ++ ii
++
+++
++
+++
++
+++
+++
+++ ++ 0
+ +++ ++
+++
++ 0
+++ +++
= Adequate; + = Poor but diag-
0
1979
The C. V. Mosby Co.
Volume 48 3
Xeroradiography
of dental structures.
III
Fig. 1. Top /
277
270
Gratt
OFdSUrg. September, 1979
Fig. 2. Left, Molar bitewing xeroradiograph demonstrating excellent visualization of teeth. metallic restorations, bone, and soft tissue structures. Note improved diagnostic imaging of gingival soft tissues covering crestal alveolar bone, and clear imaging of the cardboard bitewing tab and other oral and extraoral soft tissue structures and densities absent in conventional bitewing films (~hirc~ uro\\.s). Right, Similarly projected conventional bitewing film. Note the clear boundaries between metallic restorations and normal regions of dentin and enamel. signifying the absence of caries. The xeroradiographic image demonstrates minor edge deletion artifacts in these locations, not to be confused with recurrent caries (black arrows). Table II. Clinical radiation dosimetry measurements
Technique
Conventional film radiography Experimental dental xeroradiography
Entrance skin dose per exposure (mR)
Exit dose (at imaging detector) per exposure (mR)
204 (Range 180-230, S.D. 2 12.3, n = 27) 70 (Range 50-80, S.D. k 7.7, n = 27)
119 (Range 90-150, S.D. k 16.9, n = 27) 40 (Range 20-60, S.D. i 9.6, n = 27)
125 Medical System (Xerox Corp., Pasadena, Calif.) to imaging dental structures in vitro. We demonstrated that conventional dental x-ray units are an excellent source of radiation for xeroradiography. Futhermore, we produced high-quality xeroradiographic images of teeth, restorations, bone, and soft tissues, at radiation doses seven to fourteen times less than with conventional intraoral film radiography. ’ Qualitative and quantitative comparison of the resolution, noise, and contrast of images produced by xeroradiography and conventional intraoral film radiography showed only minor differences between the two techniques despite the reduced radiation dose with xeroradiography. Furthermore, the greater latitude of xeroradiography and its property of edge enhancement permitted superior visualization of soft tissues, composite restorations, endodontic filling materials, acrylic pontics, dental calculus, plastic crowns, and denture bases not seen well on conventional film images.’ Recently the Xerox Corporation developed a pro-
totype dental xeroradiographic system designed specifically for intraoral use, a significant step forward from the Xerox 12.5Medical System that we used previously, which could be evaluated only in the laboratory. This new imaging system is appropriately scaled down in size for intraoral radiography. It uses a black toner rather than blue plastic particles to form the visible radiographic image. These changes, among others, promise to increase the quality of dental radiographic images substantially while still permitting a sizeable reduction in radiation dose from that of conventional intraoral film radiography. The present pilot study is a preliminary in vivo evaluation of the prototype dental xeroradiographic system and assessesits potential applications in dentistry. MATERIALS
AND METHODS
The source of x-radiation for both conventional radiography and xeroradiography was a dental x-ray unit having a nominal focal spot size of 1.0 mm. and total filtration of 2.5 mm. aluminum (General Electric 100, General Electric Co.. Milwaukee, Wis.). All radiographs were taken at a target-film distance of at least 16 inches (41 cm.). using 75 to 100 kVp., IO mA., and a beam diameter of 2.75 inches (7 cm.). Average exposure times were ‘1’2second (30 impulses) for conventional film radiography and ‘/6 second (10 impulses) for dental xeroradiography. Conventional film images were recorded on Kodak D speed periapical film. DF-57 and DF-55, paperwrapped double film packets. They were developed at 70” F. (21” C.) for 4% minutes in Kodak Dental Liquid X-ray Developer (Eastman Kodak Co., Rochester,
Volume Number
48 3
N. Y), water-rinsed for 15 seconds, fixed at 70” F. (21” C.) for 10 minutes in Kodak Dental Liquid X-ray Fixer, washed for 30 minutes, and air-dried. For intraoral dental xeroradiography, we used the prototype xeroradiography image-processing system and selenium-alloy photoreceptors and cassettes described above. The prototype system charges a photoreceptor and inserts it into a lightproof cassette. After being placed in a disposable sterile plastic bag, positioned, and exposed in a patient’s mouth, the cassette is reinserted into the prototype system for development. The system produces a xeroradiographic picture in 20 seconds. The used photoreceptor is then reconditioned and may be reused repeatedly. This prototype system worked without fail, producing over 1,000 clinical dental xeroradiographs. Film packets and dental xeroradiography cassettes were positioned intraorally by conventional positioning devices now in use at the University of California, School of Dentistry (bitewing tabs, wood-block film holders, and a Fitzgerald x-ray filmholding unit). These positioning devices were easily adjusted to the greater thickness of the xeroradiography cassettes. Radiation exposure was measured on nine randomly selected patients, using lithium fluoride thermoluminescent dosimeters (Radiation Detection Co., Sunnyvale, Calif.) placed at the skin surface (over the mandibular first molar) within the area of the primary beam. These dosimetric measurements are accurate to ? 10 mR. for values below 100 mR. and to ~fr10 percent for values above 100 mR. Fifty volunteer dental patients requiring complete mouth x-ray examination (twenty to twenty-six projections) for routine dental treatment were x-rayed using conventional film techniques. Then a selected side (based on the presence of dental or oral pathology) was xeroradiographed. We positioned intraoral xeroradiography cassettes in a manner similar to the film packets positioning, attempting to produce the same projections with both techniques. Resultant images were than visually evaluated for diagnostic quality. The appearance of eighteen selected anatomic structures was judged as either optimal (+ + +), adequate (+ +), poor but diagnostic (+), or unacceptable (0). This method has been used in other investigations to evaluate diagnostic radiographic quality.“-” RESULTS
Clinical evaluations were made on 550 pairs of conventional film vs. xeroradiographic images. Table I presents the results of the analysis of anatomic structure visibility. Experimental dental xeroradiography was judged to be superior for the imaging of (1) dental anatomy, (2) fine bony detail (3) all soft tissue struc-
Xerorudiography
of dental
structures.
Ill
279
tures, (4) early and moderate dental caries, and (5) fine deposits of calculus. Conventional film technique was judged superior for imaging large, broad areas, such as when evaluating the overall radiodensity of the maxillary sinus, and also for detecting recurrent dental caries occurring under metallic (but not composite) restorations. Fig. 1 illustrates representative cases. Table II presents the results of dosimetry measurements. The radiation dose of dental xeroradiography was found to be one-third that of the conventional intraoral film technique. DISCUSSION
The new xeroradiographic images appear to be diagnostically superior to conventional film images for detecting tooth, bone, and soft tissue changes because of greater imaging latitude and the unique property of edge enhancement. These two special qualities of xeroradiography permit optimal visualization of both fine bony structures and minute calculus deposits and the clear portrayal of dental caries and many soft tissue structures previously not seen on conventional film radiographs. An added advantage is the threefold reduction in radiation dose of dental xeroradiography. The new dental xeroradiographic equipment, although still in the prototype stage, did demonstrate several features of special convenience. It produced permanent images in only 20 seconds, without the need for a darkroom. It also promises to be more economical than present-day film systems. Compared to conventional film, xeroradiographic supplies are inexpensive. Materials used include plastics, adhesives, and common solvents. The selenium-alloy photoreceptor plates can be reused for at least 1,000 images per plate. Futhermore, the xeroradiographic equipment does not require fixed installation. During our pilot clinical study we easily moved the prototype system to an alternate radiology clinic. Disadvantages observed with the prototype xeroradiographic system were remarkably few. Inappropriate adjustment of processor settings for edge enhancement parameters can create radiolucent shadows termed “edge deletion artifacts.” These radiolucent artifacts appear around sharply defined radiopacities (e.g., metal restorations), giving a false indication of recurrent dental caries (Fig. 2). However, we discovered that excessive edge deletion could be controlled, and that proper adjustment of the processing system and operator experience can readily overcome this problem. An additional difficulty involved the presence of artifacts appearing as spots and lines on 30 percent of the xeroradiographs. While these were distracting, they could readily be identified as artifacts. They probably are caused by dust particles trapped in the hand-built
280
Graft
Oral Surg. September, 1979
protytype unit and may well be eliminated as the design of the processing equipment is further refined. Other investigators recently published an independent evaluation of intraoral xeroradiography involving both a Xerox 125 medical system and the prototype dental system. 6 Their overall conclusion parallels our experience: that the prototype dental system produces images superior in quality to both conventional film and medical xeroradiographic techniques. In summary, our pilot clinical study of a prototype dental xeroradiography unit produced images superior in quality to conventional intraoral film radiography. The entire system appears to be very rapid. economical, and practical. This new imaging system promises to add new dimensions to the diagnosis, treatment, and prevention of dental diseases. I am grateful to Mr. Lothar S. Jeromin and Mr. Glenn P. Geddcs of the Xerox Corp., Pasadena. Calif., for operation of the prototype dental xeroradiographic equipment and to Drs. Troy E. Daniels and Edward A. Sickles, University ot California. Schools of Dentistry and Medicine. for their advice in preparing this manuscript.
INFORMATION
REFERENCES I. Gratt, B. M.. Sickles.
E. A., and Parks, C. R.: Xeroradiography of Dental Structures: 1. Preliminary Investigation\. ORAL SURG. 44: 148-152. 1977. 2. Gratt. B. M Sickles, E. A.. and Parks. C. R.: Xeroradiography of Dental Structure\: II. Imapc Analysis. 0~41 S~IK<,. 46: 1% 16.5. 197X. .-3 Gratt. B. M.. Sickles. E. A.. and Parks. C. R.: Uw of intraoral Cassettes for Dental Xeroradiography. OR.U SLIRG. 46: 7 17-720,
1978. 3. Sickles.
E. A.. Genant. H. K.. and Doi. K.: Comparison of Laboratory and Clinical Evaluations of Mammographic ScreenFilm System\. /)I Application of Optical Instrumentation in Medicine VI. Bellingham, Wash.. 1977, Socxty trf PhotoOptical Inswumentation Engineers. Vol. 127. pp. 30.35. 5. Gratt, B. M.. Parks. C. R.. Hall. G. S., and Sickle\, E. A.: Use of an lnclincd Footrest for lmprovmg Panoramic Dental Radiography.ORAI SURG. 47: 568-571, 1979. 6. White, S. C.. Stafford. M. L., and Beenmga, 1. R.: Intraoral Xcrorndiographg. ORAI SIRG. 46: 862-870, 197X
Rcyrrr~t r~yrtrst.c irk: Dr. Barton M. Gratt UCLA Dental School Center for the Health Science\ Los Angeles. Calif. 90024
FOR AUTHORS
Most of the provisions of the Copyright Act of. 1976 became effective on January I. 1978. Therefore, all manuscripts must be accompanied by the following written statement, signed by one author: “The undersigned author transfers all copyright ownership of the manuscript entitled (title of article) to The C. V. Mosby Company in the event the work is published. The undersigned author warrants that the article is original, is not under consideration by anotherjournal, and has not been previously published, I sign for and accept responsibility for releasingthis material on behalf of any and all co-authors.” Authors will be consulted, when possible, regarding republication of their material.