(Daniel Klauer, Rob Sutter, Stuart Rich, Steve Carstensen, Todd Morgan, Tim Mickiewicz, Bill Harrell, Dennis Marangos, Rebecca Layhe, Dan Tache, Bradley Eli, John Viviano, Harry Ball, Barry Glassman, Les Priemer, Dan Bruce, Ron Perkins, Ken Luco, Steve Lamberg, Christopher Kelly, Tony Soileau, Douglas Chenin)
The LinkedIn Discussion Group, “SleepDisordersDentistry” has just completed an open discussion on CBCT use in Dental Sleep Medicine. Here is a consensus for all to ponder.
What was asked,
“The Why, When and How of CBCT use for treatment of OSA patients, a candid discussion of what clinicians are currently doing and what is actually supported by the literature. Does it really up our game or are we just complicating the issue?”
What was said,
To start, this topic turned out to be our most heated discussion to date. Who would have thought a discussion about the use of a diagnostic tool could be so contentious? Having said that, writing the consensus article was quite straight forward, let’s discuss the clinical utility of CBCT for oral appliance therapy by category of clinical utility, and see what the “Sayers” and “Ney Sayers” had to say.
Patient Education and Motivation:
CBCT was discussed as a patient motivator; using CBCT images in a “Show and Tell” fashion to help the patient better visualize their problem. An argument was made that successfully guiding a resistant patient into seeking therapy was a worthwhile tradeoff for the radiation exposure. In defense of this suggestion, it was pointed out that the newer machines use much less radiation. In addition, shifting the view when examining another area could help initiate a discussion about the airway with the patient, making the patient more “Airway Aware”. Finally, using and communicating with this diagnostic modality could help establish relationships with medical colleagues, building better alliances.
Using CBCT “solely” to get people into therapy is unethical. CBCT does not predict the suitability for an oral appliance and does not assess the effectiveness of an oral appliance. Furthermore, there are many cost effective and non-invasive HST’s currently available. How can we justify using anecdotal, non-evidence based, “awake state” predictive factors that expose the patient to radiation when we have reliable, validated instruments that measure outcomes when the patient is actually in the “asleep state”?
Evaluate for dental pathology:
The obvious benefits of evaluating and documenting dental pathology were discussed. In fact, the most meaningful information CBCT provides us pertains to the teeth, supporting periodontal tissues and bony structures. It is simply unsurpassed for this purpose.
Of course, there were no Ney Sayers here, other than this was not the topic of discussion.
Evaluate cervical spine pathologies:
Evaluating for cervical spine pathologies was mentioned a number of times.
Clearly, CBCT is well suited to evaluate and document this issue. However, whether or not this diagnostic investigation should be done by a dentist rather than a physician opens a different discussion all together.
Evaluate the nose, sinuses for patency and pathology:
Evaluating the nasal airways for patency and pathologies was mentioned a number of times.
CBCT is a very useful tool for evaluating the nose and sinuses for pathology and or major blockage. However, one would think that as a basic screening, simply questioning the patient and testing for patency by having the patient breath through one nostril at a time while blocking the other would suffice. It was also suggested that a Peak Nasal Inspiratory Flow Meter could be used to quickly assess the patency of the nasal airways, a very benign test that does not involve radiation.
Following a non-invasive and simple screening, should further evaluation be warranted, the required imaging could be ordered by the attending surgeon.
Evaluate TMJ health:
Evaluating the TMJ was mentioned repeatedly, which could provide information useful in appliance selection. When asked how this information would be used, the only thing mentioned was that if DJD was noted, an appliance with freedom of movement would be used facilitating healing of the joint.
Documenting the presentation of the TMJ prior to treatment was also discussed. This would serve to protect a clinician that delivered an oral appliance in a patient with asymptomatic DJD, should the condition be noted at a later date.
It was also suggested that the recent 4d capabilities will allow clinicians to evaluate the TMJ in motion and with protrusion, helpful for case selection, selecting VDO, and predicting TMD risk.
Evaluation for DJD was suggested to ensure that an appliance that did not restrict movement was used for an afflicted patient. However, a number of clinicians mentioned that the exclusive use of appliances that do not restrict movement negates the necessity for this evaluation.
The question then becomes, in the absence of symptoms, is a CBCT of the TMJ necessary and how does it alter clinical decisions. Although I asked this several times, aside from using an appliance that did not restrict jaw movement, no one presented any other use of this information aside from the “CYA” argument.
Evaluation of the Airway to Establish Candidacy or Predict Outcomes:
It was suggested that in the near future airway space will have an algorithm with a defined risk factor useful for OSA management, and that CBCT is currently useful to verify where the obstruction is, the nasopharynx, oropharynx, or hypopharynx? Further along these lines, some clinicians mentioned that imaging the airway pre and post mandibular repositioning with the bite registration prior to making the appliance helps to ensure airway dimensional improvement that corresponds with literature recommended norms and also helps to determine the amount of advancement and VDO required for an optimum outcome.
Other clinicians were more conservative, stating that there is nothing in the literature at present that shows how an image points to responder vs. non-responder to oral appliance therapy, but perhaps users of CBCT can build data in support of this initiative. In other words CBCT documentation of airway changes associated with oral appliance therapy could provide insights and a body of evidence. It was also suggested that CBCT scans of the airway could be restricted to when the patient’s history suggests further evaluation.
The following citations were provided with the suggestion that there is a trend in the literature that supports using CBCT to predict responders to OAT, acknowledging that more work needs to be done.
Marcussen et al. Do Mandibular Advancement Devices Influence Patients' Snoring and Obstructive Sleep Apnea? A Cone-Beam Computed Tomography Analysis of the Upper Airway Volume. J Oral Maxillofac Surg. 2015 Sep;73(9):1816-26. doi: 10.1016/j.joms. 2015.02.023. Epub 2015 Feb 26.
Abramson et al. Three-dimensional computed tomographic analysis of airway anatomy in patients with obstructive sleep apnea. J Oral Maxillofac Surg. 2010 Feb;68(2):354-62. doi: 10.1016/j.joms.2009.09.087. Epub 2010 Jan 15.
Cossellu et al. J Craniofac Surg 2015. Three-Dimensional Evaluation of Upper Airway in Patients With Obstructive Sleep Apnea Syndrome During Oral Appliance Therapy
Physical laws such as Poiseuelle's Law and Bernoulli's Law of fluid dynamics were cited as rational for using CBCT to ensure the airway increases in size with mandibular advancement.
Pharyngometry was also mentioned as a “Radiation Free” alternative tool to assess the upper airways. Enabling easy assessment of both protrusive and vertical jaw position alteration.
Currently, no literature evidence supporting airway size as measured through CBCT while upright and awake is helpful in establishing a jaw position that ensures or predicts efficacy. Furthermore, physiological factors play a meaningful role too often for it to be exclusively about airway size.
Many clinicians discussed the “pinch point”, which refers to an extreme reduction in airway caliber in either the nasal or oral airways that can be documented using CBCT, representing this as the “source” of the airway problem. However, there is no evidence in the literature that this “Pinch Point” is actually related to the site of airway collapse. In fact, if one reviews the literature about the site of collapse during sleep, it occurs at multiple levels: velopharynx, oropharynx, and/or hypopharynx. Complicating the issue further, the majority of OSA patients exhibit more than one site of upper airway obstruction during sleep and the pattern of these obstructions varies with sleep stage and body position. We have actually known this for a long time.
Morrison et al. Pharyngeal narrowing and closing pressures in patients with obstructive sleep apnea. Am Rev Respir Dis 1993;148:606–611
Hudgel DW. Variable site of airway narrowing among obstructive sleep apnea patients. J Appl Physiol 1986;61: 1403–1409
Boudewyns et al. Site of upper airway obstruction in obstructive sleep apneoa and influence of sleep stage. Eur Respir J 1997;10:2566–2572
So, one has to ask, just how useful is documenting this “Pinch Point” anyway? And, how will it alter clinical decisions?
We know that the hard tissue contour of a CBCT scan is not related to the soft tissue surface. Validation studies with Sensitivity and Specificity have been performed on hard tissues, but not on soft tissues. So, soft tissue findings on CBCT imaging begs the following question, is it accurate? Without evidence that soft tissue imaging of the upper airway through CBCT is accurate one must question the significance of the finding and whether it is of any importance to the treatment being considered.
On the other hand, the pharyngometer has been validated for accuracy at baseline habitual posture with good sensitivity and specificity. However, it has not been validated at other than baseline posture and this should be done before assuming that moving the jaw does not impact on accuracy of the readings. Then of course, there is the standard argument of awake vs. asleep and upright vs. supine, which applies to both CBCT and Pharyngometry.
It was also suggested that a dentist that does not use CBCT to evaluate the patient’s airway prior to proceeding with an appliance was behaving more like a technician than a dentist. My response to this was, “No, I don't think we are behaving like technicians by staying on task and using literature based protocols, all the while reducing barriers to therapy by keeping things simple and cost effective.”
There was no shortage of clinicians with over 20 years of experience expressing the following sentiments:
“Treating to symptom resolution results in better outcomes than treating to changes in airway dimension as documented by CBCT’
“Surgical procedures such as those performed by an ENT could always be considered if the appliance fails to take care of the problem. Of course, the surgeon you refer to will have their own view on what type of subjective/objective documentation is required; naso-endoscopy, rhinometry, CBCT etc.”
“CBCT imaging in a dental sleep medicine office setting presents more disadvantages (not useful for screening, possible radiation concerns).....than benefits at this time”
I published an article entitled "Acoustic Reflection: Review and Clinical Applications for Sleep-Disordered Breathing" in Sleep and Breathing in 2004. At that time I was very excited about the role Pharyngometry "COULD" play in the management of OSA with an oral appliance. However, it is now 2016 and we are still waiting for evidenced based literature on the role it could play. Yet many clinicians’ have been using it routinely, all these years. Bottom line is, many articles have been published on the potential utility of CBCT, but protocols for its application need to be established in an evidence based manner, before we start using it for this purpose on patients, not the other way around as many have suggested. I have yet to see evidence based protocols as to how CBCT derived information can be used to alter appliance construction or adjustment decisions. So, why complicate things. What we do is either evidence based or not. I believe that if we are experimenting on our patients, that fact should be disclosed.
CBCT is very impressive and has many applications. I can definitely see an application for what we do, but further research is needed to establish meaningful protocols. It’s really “Cool” is simply not a sufficient reason to incorporate CBCT into your Dental Sleep Medicine practice. Eckert et al. published a very nice study in 2013 that I believe is relevant to this discussion. Their Conclusions:
"nonanatomic features play an important role in 56% of patients with OSA".
With "nonanatomical features" having such a high level of influence, I ask, what value can simply evaluating the anatomy be?
Check it out...
Quite frankly, regardless of how “Cool” it is and it’s diagnostic acumen regarding other areas, suggesting that CBCT should be a standard of care in Dental Sleep medicine complicates things unnecessarily and serves as a potential “Barrier to Treatment”, which is very much a concern.
To Sum Up:
A number of clinicians stated that the clinical use of CBCT imaging has been established in the trenches but the literature has yet to catch up. Quite frankly, such a comment would never fly in a discussion amongst physicians. Furthermore, any clinician using or providing a service to a patient that is not evidence based should be disclosing that fact to the patient. That disclosure could go something like this,
“we are going to image your airway with a really cool device called CBCT. The image we will be able to look at together will show us in 3D, the size of your airway both at rest and once I advance your jaw. It will be really cool to see the airway get bigger with jaw advancement and exactly just how much the airway enlarges. However, I want you know that there is no way for me to predictively use that information to alter my treatment plan, nor will this information be able to confirm that your oral appliance will adequately mange your sleep apnea. But I assure you, it will be really cool to see”.
Prioritizing the patients’ needs and providing the best service possible was prioritized by some clinicians over additional cost of CBCT imaging. Some pointing out that the cost of a CBCT scan is typically reimbursed by insurance (at least in the US). It was also suggested that perhaps the rational for those against using CBCT is their reluctance to spend the money to purchase a CBCT unit, all interesting points of view, but without literature support regarding how CBCT images can be utilized, these are simply rationalizations in the minds of those clinicians.
Douglas Chenin, a clinician that is very involved with CBCT earned the right to be “quoted as he wrote it”. I believe Doug’s representation of CBCT is fair and literature based, I thank him for sharing and I feel it is a fair summary of what CBCT brings to the table regarding tha mangement of OSA patients with an oral appliance.
“CBCT imaging provides a tremendous value to us and our patients in helping us see our patient as a whole, as they are in 3D, and how we can better coordinate surgical care with other professionals when needed. The questions that I want to ask with my CBCT scans are:
"Does my patient have any head and neck, dental/skeletal, sinus and/or TMJ pathology?
What surgical treatments are essential, recommended, possible or ruled out based on their 3D internal anatomy?"
As we get more research, perhaps we can add questions like:
"how predictable" is OAT for specific patients / patient types?
But by the time we get enough research on this, I hope and think that auto-titration devices with HSTs will be available and will be better for answering this type of question.
This does not devalue CBCT at all as CBCT imaging is extremely valuable for answering critical anatomy and pathology related questions that we can't completely address with intra/extra oral exams, HSTs or health questioners.”
Trying to answer other questions with our CBCT scans at this point is most likely premature and potentially distracting from the real value of what CBCT imaging can do for us and our patients. I say this as someone who has/is constantly trying to push the limits of CBCT imaging, but nonetheless it’s important to remember what it was designed to do and that it does that extremely well.”
I would like to express a heartfelt thanks to all that participated in this discussion. As always, these consensus articles should be considered working documents, meant to guide those clinicians new to this field and also present some valuable insights to those of us that have been at it a while. I look forward to future discussions on our SleepDisordersDentistry LinkedIn group!
John Viviano DDS D ABDSM
Facility Accredited by American Academy of Dental Sleep Medicine