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Missed Diagnosis Using Conventional
2-D Radiography
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OVERVIEW Due to its ability to capture three-dimensional views in multiplanar slices, Cone Beam Computed Tomography (CBCT) is proving superior to conventional radiography in the evaluation of endodontic anatomy and dental disease. In this case report, Dr. Daniel McEowen describes a clinical situation in which use of this advanced 3-D imaging technology enabled him to more accurately diagnose the cause of a patient's endodontic failure and to plan for extraction and immediate implant placement. Dr. McEowen then summarizes the limitations of 2-D radiography when compared to 3-D CBCT imaging technology in the video supplementing his article.
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Daniel McEowen, DDS
Instructor, Master of the World Clinical Laser Institute (WCLI)
drdan13106@gmail.com |
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| Dr. Daniel McEowen is a 1982 graduate of Loma Linda University School of Dentistry and has been in private practice for 26 years. He currently practices in Hagerstown, Md., in a multidiscipline practice. A founding member and Master of the World Clinical Laser Institute (WCLI), he lectures and trains internationally
in laser dentistry techniques, and teaches a course for erbium and diode lasers with the Masters of Laser Dentistry. He has been active in obtaining FDA approval of oral surgery techniques using erbium lasers. Dr. McEowen also owns 3D Imaging Center in Maryland, lectures throughout the U.S. on cone beam technology, and is an advanced trainer for PreXion 3D cone beam systems. He is active in implantology and a member of the ICOI. |
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Cone Beam Computed Tomography (CBCT) is
becoming increasingly popular in dentistry for diagnosis and treatment planning. Use of this three-dimensional imaging technology can increase diagnostic accuracy compared to conventional two-dimensional digital periapical and panoramic radiography. The inherent distortions and limitations of 2-D radiographs make it much more difficult to complete an accurate case diagnosis. Some of these limitations include: elongation and foreshortening of the target tissues, overlap of structures in front of or behind the target tissues, tissue density that is not easily interpreted in bone or soft tissues, and resolution differences of various film and digital receptors.
Many of the issues associated with conventional 2-D radiography can be eliminated or greatly reduced with the use of 3-D CBCT. CBCT uses a cone-shaped beam and digital processing to create a 3-D image that does not contain magnification, distortion and overlap of anatomy. Before investing in 3-D imaging, a clinician will need to choose a "field of view" (FOV). FOV refers to the area of the anatomy that is captured by the scan. Medium FOV CBCT scanners offer focal spot sizes down to 0.15 mm and voxel sizes down to 0.076 mm. The size of the focal spot and each voxel (volume pixel) determines the resolution of the image; the smaller the focal spot and voxel, the better the resolution.1,2 Smaller focal spot sizes and higher resolution enable clinicians to make very accurate diagnoses in most cases. CBCT also offers multiplanar views (MPV) in slices as thin as 0.05 mm thick. These MPV are cross sections through the volume of information in axial (x-z axes), coronal (x-y axes) and saggital (z-y axes) views. Using sophisticated software, the volume can be sliced at any oblique direction to view pathology from virtually any angle and thickness. The ability to view diseased areas in different planes can eliminate guesswork during diagnosis and help determine the least invasive procedure necessary to eliminate the dental disease.
The following case study illustrates how using CBCT technology can improve the success of endodontic diagnosis and treatment.
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Case Report
This case follows the three-year treatment of a 38-year-old female with a history of failed root canal procedures and eventual extractions. In 2009, she presented with vague pain in the lower right mandibular quadrant and complained she could not bite in the area. A digital periapical radiograph taken in September 2009 of the lower right bicuspids and molars revealed no apparent pathology (Fig. 1). Tooth #28 had slight pain with percussion and some fleeting pain to cold on the buccal surface lasting less than five seconds. At some point in the three months prior to her visit, a new crown had been placed on tooth #5. An occlusal adjustment was performed on this crown to relieve the stress on tooth #28.
Several months later, the patient was again seen in the office for tooth #28. Her symptoms had worsened and she was experiencing prolonged discomfort in the tooth. Pulp testing indicated a nonvital root and root canal treatment was completed. A new periapical radiograph was taken at this appointment but did not show definitive periapical pathology. Her symptoms were eliminated and she returned to normal use and function on tooth #28.
Eighteen months passed and the patient returned for extreme pain in tooth #28. A new periapical radiograph was taken that revealed little to no abnormal pathology (Fig. 2). A CBCT scan was also taken that revealed a large lesion on the distal side of the root (Fig. 3). Further examination of the scan revealed a lateral canal midway down the root with a 3 mm by 5 mm area of radiolucency in the interproximal bone (Fig. 4). Root canal retreatment was discussed with the patient and refused. Having been successfully treated with dental implants in the past, she decided on implant treatment instead. Immediate implant placement after extraction was selected as the treatment of choice because it would greatly decrease the patient's treatment time.
Luxators were used to atraumatically remove the offending tooth, and surgical spoons were used to mechanically debride the socket. The granuloma was removed in its entirety, and the entire area of the socket was decontaminated using laser energy.
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Osteotomy drills were then used to modify the socket, and an implant was immediately placed in the modified socket (Fig. 5). The discrepancy between the socket shape and the diameter of the implant on the buccal and lingual was less than 1.5 mm, so no additional grafting materials were placed. Within two to four months, native bone will fill in the gap.
A postoperative CBCT scan taken immediately after implant placement revealed the position and the engagement of the implant in the apical half of the socket (Fig. 6, Fig. 7). The patient is healing well and will soon move forward with the final restoration. Compared to the 2-D periapical radiographs, the 3-D and MPV views provided by the CBCT scan enabled us to make a much more complete diagnosis.
Conclusion
Three-dimensional CBCT offers a more complete view of dental anatomy and disease than traditional 2-D radiography alone. Using this technology allows the clinician to more accurately evaluate endodontic anatomy and better diagnose the true extent of dental disease. Having a more accurate diagnosis results in a more appropriate treatment plan and helps guide a patient's treatment toward a successful outcome.
For clinical questions, contact Dr. Daniel McEowen at drdan13106@gmail.com. For technical questions, contact Keith Bateman at kbateman@prexion.com.
References
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