3D vs. 2D Imaging – Is the 2D Ceph Still Necessary? (Part 2)

Last week, we touched on the why orthodontists need a 2D cephalometric system in their office and the difference between the different units. This week, I want to discuss the tangible advantages of having a 2D cephalometric unit available in your office.

The key benefits of using true 2D cephalometric imaging, as opposed to cephalometric images reconstructed by a 3D unit include:

• Elimination of motion artifacts through one-shot acquisition

• Improved workflow

• Ability to evaluate treatment response of patients who started treatment with a 2D ceph

• Decreased legal liability

Elimination of Motion Artifacts through One-Shot Acquisition

When a 3D scan is used to capture the images necessary for a cephalometric image, the risk of image distortion is increased. Considering the age range of patients who visit orthodontic practices, it makes sense that the longer they must sit for a scan to be completed, the higher the chance of image distortion—as well as for increased dose.

“High quality 2D cephalometric and panoramic images still have an important place in today’s Orthodontic practice, even given the availability of low dose 3D images,” said Dr. James Mah, Current Program Director of the Orthodontics and Dentofacial Orthopedics Residency program at the University of Nevada, Las Vegas. “The instant exposure available with a one-shot ceph is very useful in orthodontics when dealing with fidgety and special needs patients. Conditions such as tremors or behavioral challenges can make it impossible for the patient to hold still for even a few a seconds during a 3D scan.”

Improved Workflow

When a 3D imaging system is used to capture a cephalometric view, the following steps can increase the overall workflow process.

• waiting for the patient to be scanned;

• waiting for the cephalometric image to be reconstructed from the 3D slices; and

• reading and documenting any findings on the 3D volume.

With one-shot, 2D cephalometric imaging, orthodontists simply capture the image to get the necessary information for their patient. This time savings translates directly into more time to spend with patients as well as to perform essential orthodontic tasks.

Ability to Evaluate Treatment Response of Patients Who Started Treatment with a 2D Ceph

Another problem with limiting imaging to only 3D is that you cannot correlate ceph images captured in 2D with images extrapolated from a 3D volume. The training manual for one 3D imaging system manufacturer states "Please keep in mind that these reconstructions are one to one and the two sides of the skull are NOT magnified as in traditional film based cephalometric images." Dr. Robert L. Waugh, of Waugh + Allen Orthodontics in Athens, Ga, says that “Images similar to cephalograms obtained from 3-D CBCT scans may not be used to evaluate the growth and longitudinal results of orthodontic therapies in relation to conventional cephalograms.” The net result is that you lose the ability to superimpose images of your patients who started treatment before the incorporation of CBCT unless you maintain your ability to take a standard 2D ceph.

Decreased Legal Liability

In order to construct a cephalometric view from a CBCT imaging system, the patient’s anatomy is scanned in 3D. This requires doctors to evaluate all of the CBCT data, not just the desired cephalometric view.

“Each time a 3D volume is captured, it should be read in its entirety either by the doctor or by a qualified radiologist,” said Dr. David M. Sarver, of Sarver Orthodontics in Birmingham, Ala. “If the full 3D volume is not read and the findings documented, the Orthodontist will be exposed to medical legal risk. This may add time and cost to the case without orthodontic clinical benefit.”

This means that even if the scan was performed solely for the purpose of extrapolating a lateral cephalometric view, reading the scan and documenting the findings and communicating them to the patientis still legally required by orthodontists. Using a 2D cephalometric imaging system eliminates these risks so doctors can capture the image they need without the additional work.

“Dentists should be held to the same standards as board-certified oral and maxillofacial radiologists when using CBCT,” said Dr. Waugh. “This means that every time a CBCT scan is taken, a qualified person should interpret the image volume, create a written report, and properly communicate the findings to the patient. That is something I don’t think Orthodontists are going to want to do each time an image is captured.”

What do you think of the role that 2D cephalometric images play in the orthodontic practice? Let's discuss your opinion in the comment section below.