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Published on Sunday, 31 January 2010 18:00

by Ahmad Abdelkarim, DDS, MS, and Dipak Chudasama, BDS, MSc, MORTH RCS, MBA

What orthodontists should be looking for in cone beam CT scans

Cone beam computed tomography (CBCT) allows the clinician to view the maxillofacial region in three planes and eliminate superimposition, distortion, and magnification inherent to two-dimensional imaging.

It is important for the orthodontist to interpret the whole scan volume, not just the area of interest. As such, the purpose of this article is to describe a systematic approach to CBCT evaluation by orthodontists.

Figure 1: Axial section at the level of the maxillary sinus floor shows the maxillary posterior teeth roots are in contact with the cortical plate of the sinus.

Figure 2: Coronal section at the level of the first molar shows dilaceration of the mesial root of the upper right first molar.

Figure 3: Sagittal section of the maxillary anterior region shows a thin buccal plate and a dehiscence over the upper left central incisor.

Figure 4: Sagittal section at the level of the left condyle shows flattening and erosion of the condylar head, suggestive of degenerative joint disease.

Figure 5: Coronal section at the level of the condyle shows flattening of the condylar head.

Figure 6: A cropped panoramic image derived from the CBCT scan. All teeth are present, except the third molars. The upper right lateral incisor appears to be a peg lateral.

Figure 7: A lateral cephalometric image derived from the CBCT scan.

Figure 8: A 3D reconstruction derived from the CBCT scan shows an unruptured maxillary right second premolar.

How to Look

To look at a CBCT scan, the orthodontist needs to adjust the contrast and brightness, and scroll through the axial, sagittal, and coronal sections to identify pathology and anatomic variants.

What to Look For

1. Impacted teeth
2. Temporomandibular joint evaluation
3. Paranasal sinus evaluation
4. Systemic findings
5. Dental findings
6. Orthognathic surgery
7. Vertebral body evaluation

Conclusion

The use of CBCT in orthodontics is expanding rapidly. As imaging technology continues to improve and radiation doses decrease, CBCT will likely become the standard of care for orthodontic diagnosis and treatment planning.

Ahmad Abdelkarim, DDS, MS, is an assistant professor of orthodontics and dentofacial orthopedics at Loma Linda University School of Dentistry. He can be reached at

Dipak Chudasama, BDS, MSc, MORTH RCS, MBA, is an associate editor of Orthodontic Products. He can be reached at

References

1. Mah JD, Hatcher D. Current status and future needs in craniofacial imaging. Orthod Craniofac Res. 2003;6(Suppl. 1):10-6.
2. Vannier MW. Craniofacial computed tomography scanning: technology, applications and future trends. Orthod Craniofac Res. 2003;6(Suppl 1):23-30.
3. Danforth RA, Dus I, Mah J. 3D volume imaging for dentistry: a new dimension. J Calif Dent Assoc. 2003;31:817-823.
4. Siwerdsen JH, Jaffray DA. Cone-beam computed tomography with a flat-panel imager. Med Phys. 1999;26:2635–2647.
5. Hashimoto K, Arai Y, Iwai K, Araki M, Kawashima S, Terakado M. A comparison of a new limited cone beam computed tomography machine for dental use with a multidetector row helical CT machine. Oral Surg Oral Med Oral Path Oral Radio Endo. 2003;95:371-377.
6. Schulze D, Heiland M, Thurmann H, Adam G. Radiation exposure during midfacial imaging using 4- and 16-slice computed tomography, cone beam computed tomography systems and conventional radiography. Dentomaxillofacial Radiology. 2004;33:83-86.
7. Danforth RA, Miles DA. Cone beam volume imaging: 3D applications for dentistry. Ir Dent. 2007;10(9):14-18.
8. Walker L, Enciso R, Mah J. Three-dimensional localization of maxillary canines with cone-beam computed tomography. Am J Orthod Dentofacial Orthop. 2005;128(4):418-423.
9. Hilgers M, Scarfe W, Scheetz J, Farman A. Accuracy of linear TMJ measurements with cone beam computed tomography and digital cephalometric radiography. Am J Orthod Dentofacial Orthop. 2005;128:803-11.
10. White SC, Pharoah MJ. Oral Radiology, Principles and Interpretation. 6th Edition. St. Louis: Elsevier; 2009.
11. Kau CH, Cronin A, Durning P, Zhurov AI, Sandham A, Richmond S. A new method for the 3D measurement of postoperative swelling following orthognathic surgery. Orthod Craniofac Res. 2006;9(1):31-37.
12. Cevidanes LH. Styner MA. Proffit WR. Image analysis and superimposition of 3-dimensional cone-beam computed tomography models. Am J Orthod Dentofacial Orthop. 2006;129(5):611-618.
13. Cevidanes LH, Bailey LJ, Tucker GR Jr, et al. Superimposition of 3D cone-beam CT models of orthognathic surgery patients. Dentomaxillofacial Radiology. 2005;34(6):369-375.
14. Bailey LJ, Cevidanes LH, Profitt WR. Stability and predictability of orthognathic surgery. Am J Orthod Dentofacial Orthop. 2004;126 (3):273-277.
15. Shi H, Scarfe WC, Farman AG. Three-dimensional reconstruction of individual cervical vertebrae from cone-beam computed-tomography images. Am J Orthod Dentofacial Orthop. 2007;131(3):426-432.

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