VIEWING THE PATIENT AS A WHOLE:
A CBCT RADIOGRAPHIC EXPLORATION
This webinar aired live on March 3, 2020, but you can still view the recording.
Dr. Tamimi earned her dental degree from King Saud University, Riyadh, Saudi Arabia in 1999. She trained at Harvard University and earned a doctorate of medical science (DMSc) and certificate of fellowship in Oral and Maxillofacial Radiology in 2005. She is board certified by the American Board of Oral and Maxillofacial Radiology (ABOMR). Dr. Tamimi is a co-author on “Diagnostic Imaging, Oral and Maxillofacial”, the lead author on “Specialty Imaging: Dental Implants”, and “Specialty Imaging: Temporomandibular joint”.
"The chief complaint of this patient is pain in the area of the mandibular left second molar. Dentists sometimes get caught up in looking for the obvious causes of dental pain, such as periapical pathosis, and this distracts them from looking at the bigger picture. The bigger picture (the craniofacial complex) may offer clues as to the true cause of the patient’s pain. This case exploration yields multiple additional findings in the craniofacial complex that should be reported on, and demonstrates the systematic method required for such an evaluation."
1.Is there ever a time you guys would prefer artifact reduction enabled on the CT (Vatech Paxi3d)?
Metal Artifact reduction (MAR) algorithms are found in multiple software and are used to reduce metal artifact around structures such as implants. This may enhance visibility of the structures but may not be very useful in the direct vicinity of the implant.
2. When doing your report is there a standard protocol of cuts that you use
I always include a Pano. For TMJ/Airway/Ortho cases, I include TMJ sagittal and coronal oblique cross sections. Axial views of the TMJs, 3D reformation of the skull in the frontal and lateral views and an airway volumetric image. For implants, I include cross sections of the alveolar processes. If there is something that I want to bring to my clinician’s attention, I will add that as well.
3. Do you take all scans in CBCT with maximum intercuspation position (MIP)?
For evaluation of the TMJs spatial relationships, I recommended a scan in maximum intercuspation. This is important if the purpose of the scan is TMJ, Airway, orthodontic, craniofacial pain. For implants where the scan will be used for surgical guide fabrication or simplant conversion, the software manufacturers often ask that the teeth be apart.
4. For orthodontic patients we normally take the images under extra low dose. Would you be able to diagnose all you did with an extra low dose setting?
Fine details may not be visible on extra low dose setting. These details include ankylosis or early erosions on the articular surface of the TMJs in the case of idiopathic condylar resorption.
5. The endodontic treatment patency was something that wasn't evaluated (eg underfilled, not upto the apex etc). Is that something the radiologist checks or is that the preference of the endodontist?
My apologies. I usually do check the root canal fillings for overfill, underfill..etc, especially in the case of the presence of periapical disease. It must have slipping my mind while recording this video
6. DoIt's always great to attend your great seminars. Do radiologists at Beamreaders educate the dentist as what field of view would be the best, so they don't overradiate their patients? I know a dentist who takes the largest FOV, 16 x 23 for all TMJ evaluation and sends them all to beamreaders. Nobody has suggested that he can lower the FOV! you have some references on orthodontic therapies and CBCT findings and Airway
For a TMJ scan, you must evaluate the entire craniofacial complex, not just the TMJ. There are too many clues to the diagnosis that reside in areas away from the TMJs such as changes in the airway, Cervical spine and jaws.
7. I see that the size that you are using is from the top of the orbits to the bottom of the jaws and not including the brain. But 16x23 includes the whole brain. Wouldn't you think that is excessive?
To evaluate the craniofacial complex for the interactions I mentioned in this video (airway, TMJ, occlusion, cervical spine), a 16 cm field of view craniocaudally is necessary. 23cm is a little excessive, but may have certain applications.
8. In a case of cervical dystonia what might you see in the TMJ area or are there specific signs.
The analysis of cervical dystonia is more of a clinical one. The craniovertebral junction alignment on the CBCT may be a result of patient positioning on the CBCT or may be due to true rotation or malalignment. With the malalignment of the craniovertebral junction come possible malalignment of the temporal bones in relation to the condyles. Mariano Rocabado is a good resource for understanding these malalignments.
9. Should the patient always be in MIP when taking the CBCT
I answered this question previously.
10. Most of the CBCT machines have something for the patient to bite onto, should I just use the chin rest when taking CBCT?
If you are trying to evaluate the relation of the TMJs to airway to occlusion, the teeth should be in MIP. If you use a bite stick, the relationship is edge-to-edge and will not give you clues to how the occlusion relates to the TMJs
11. It is nice to see that condylar position and condition are noted to be related to occlusion. The missing information in this presentation is what is actually happening to disc position. MRI is really needed to completely assess the TMJ condition. The CBCT gives a real good reason to get an MRI. Thanks
Thank you for asking this question. Disc position is the topic of another future webinar! Sometimes the CBCT gives clues to the presence of disc displacement, but the teeth need to be in MIP in order to see these clues. You cannot see the soft tissues on CBCT, but you can see the clues.
12. Is there a way to orient the patient to get the right posture (since you said in the scan the patient was forwardly seated, so the airways were opened)
Clinically, you can assess the patient’s posture, but when it comes to CBCT it is more important to get a clear scan that has no motion artifact, and that sometimes requires moving the head out of the natural head posture to get it still with a chin rest or a head strap. Just remember that what you see on the scan in terms of the neck alignment does not always correspond to natural head posture.
13. If we see calcifications of carotid artery in the Pano, we should we warn the patient to see their doctor? Should we do a CBCT after the pan? It hasn't been shown in the literature that there is a direct correlation to stroke.
A calcified atheroma is a sign of a stable atherosclerotic plaque. It’s an indication of cardiovascular disease, but it is not as dangerous as a non-calcified plaque, which could potentially dislodge and cause a stroke. Clinical correlation to cardiovascular disease history is recommended.
14. How deficient is the maxilla in the AP dimension?
I did not check in this case, but I do check this and the transverse dimension of the arches in airway cases.
15. When taking the scan where do you ask the patient to place the tongue?
If you are taking the scan to compare the effect of treatment on airway dimensions, the tongue and neck should be in a reproducible and similar position on both scans. I would say that the most reproducible tongue posture is with the entire tongue to the roof of the mouth.
16. Do you have some references on orthodontic therapies and CBCT findings and Airway?
There are several articles on Pubmed tackling different philosophies (Airway Centric Orthodontics, the effect of facemasks on airway dimensions, the effect of Herbst Appliances on airway, distraction osteogenesis, SARPE, MARPE.etc). It depends on what you are looking for.
17. What is the protocol to follow while assessing the airway? like with normal values?
The value of CBCT in airway assessments lies in the anatomic evaluation of the upper respiratory tract for risk factors of sleep-disordered breathing. This includes nasal cavity, sinuses, nasopharynx, oropharynx, jaws, tongue and cervical spine. The volumetric measurements of the oropharynx are meaningless without clinical correlation.
18. The pano that was generated (and shared in your webinar) looks great. How can we generate such a clear pano?
You have to draw your spline line along the arch and then you can expand the focal trough in the software to include the teeth. It gets tricky when patients have severe class II and III.