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Cone Beam Computed Tomography and Computer Controlled Mandibular Positioner in Conjunction with a Level III Sleep Study


March 12, 2019
by Dr. Michael Parchewsky, BSc (Hons), DMD, FAGD; Ross McKercher, BSc

A Systematic Approach to Obstructive Sleep Apnea: A workflow using SICAT and Zephyr Sleep Technologies: SICAT Air and the MATRx plus in Tandem

Introduction: Obstructive Sleep Apnea
Obstructive sleep apnea (OSA) is a prevalent chronic disease seen by both doctors and dentists. OSA is characterized by the prevention of regular breathing due to the upper airway collapsing during sleep, resulting in a complete or partial obstruction. The necessity for diagnosis and treatment of OSA is due to its comorbidities, such as: cardiovascular morbidity (e.g. arrhythmia); daytime sleepiness; cognitive impairment; higher risk of degenerative brain disorders; and the effect on overall quality of life. Furthermore, mental fatigue affects work performance, and can increase chances of motor vehicle accidents. 1,2 These issues show the significance of OSA on a person’s overall health and the need for public knowledge of this chronic disease.

When the upper airway collapses and completely obstructs breathing for 10 seconds an apneic event occurs; if breathing is prevented for less than 10 seconds or takes considerable effort, a partial collapse of the upper airway occurs and is called a hypopnea event. Both disruptions in regular breath affect the oxygen desaturation and break up sleep. Generally, having an apnea-hypopnea index (AHI) – average number of events per hour – above 5 qualifies an individual of having OSA.3 OSA is still a relatively underground disease that has large ramifications on a person’s health and quality of life. As health care providers, it is necessary to recognize, help with the diagnosis pathway, and treatment of this chronic disease. Therefore, this article will outline the diagnosis and treatment of OSA using Zephyr Sleep Technologies and SICAT Air software.

Screening Tools
OSA is relativeely unheard of by the public, even with its moderately large morbidity rate. Affecting approximately 10% of men, 5% of women, and 5% of children, many go undiagnosed, where it is believed that 37% of the population is affected. 3,4 As a dentist, one of your patient’s may unknowingly have OSA since patients do not get the proper screening and referral to trained medical providers. To prevent this, traditionally easy to ask/answer questionnaires are used as screening tools – Epworth Sleepiness scale, STOP-Bang, and Berlin Questionnaire. 5 One issue with qualitative questionnaires is that patients underscore their symptoms, giving false negatives for OSA diagnosis. 6

One novel approach, is to use Dentsply Sirona’s SICAT Air software with Cone Beam Computed Tomography (CBCT) technology to measure the minimum surface area of a patient’s upper airway. By taking radiographic slices of a person’s airway, layering them, and rendering a three-dimensional (3D) image, a colourised model of a person’s upper airway can be created (Fig. 1). The model itself is coloured, with green being normal and red/yellow being smaller than normal. SICAT Air identifies the lowest cross-sectional area on the produced windpipe, allowing the identification of the constricted area. On average, people with OSA have a smaller minimum cross-sectional imaging then normal airways. 7 Though the ranges of what minimum cross-sectional area falls into OSA is questionable, most of the data hovers around 98.5 mm28 as the turning point between normal airway and an OSA affected airway.

Fig. 1

SICAT Air scan showing a 3D rendered constricted airway.

This minimum cross-sectional area, with the use of a sleep questionnaire, can act as a powerful screening tool to aid diagnosis as it gives visual confirmation to both healthcare professionals and to patients themselves. Patients with symptoms of OSA from questionnaires or with a restricted airway on the SICAT Air software, can then proceed with a sleep study to confirm OSA diagnosis.

Diagnosing OSA
The diagnosis of OSA is performed using a sleep study – Level I being in a laboratory setting and level III being a take-home study – that records a patient’s sleeping habits. Currently in some provinces, the wait times for a level-1 sleep study are around 4-6 months based off of urgency. A level-1 sleep study is a very robust system to diagnose and test patients for all sleep and breathing disorders. 9 However, with level III sleep studies, patients are able to be seen much quicker and have the ability to sleep in the comfort of their own home. Both studies record how long a patient stops breathing, whether they are snoring, heart rate, and how much effort it takes for the patient to breathe. 9 This data is then amalgamated to give a diagnosis.

Currently, there are many level III sleep study machines available to dentists and medical professionals; however, the most applicable sleep study machine for Dentistry is the new MATRx plus, manufactured by Zephyr Sleep Technology (Fig. 2-3). It was developed from a level 1 sleep protocol and converted to a level 3 take home unit recently. It has a strong body of research behind it as it was developed in level 1 facilities. 10 It has the ability to run a theragnostic sleep study – an exam that checks Oral Appliance (OA) eligibility. This works by running a basic sleep study with a computer controlled mandibular positioner (CCMP) that adjusts the patient’s mandible during sleep. The MATRx plus can be given out by dentists, allowing a full treatment pathway in their office, giving patients the easiest way to treat their OSA. The Zephyr Sleep Technologies online portal allows quick access for certified sleep physicians to review the baseline (diagnostic) or theragnostic sleep study. The dentist, with guidance from a Zephyr Sleep Technologies sleep physician, is able to determine patients that will benefit from an oral sleep appliance versus the patients that should be referred for a continuous positive airway pressure (CPAP) assessment.

Fig. 2

MATRx plus Case.

Fig. 3

MATRx plus Tablet, Recorder and sensors including effort belt, nasal cannula, MATRx plus, tablet, Massimo pulse oximeter mandibular positioner.

Treatment
For the treatment of OSA, the gold standard of care is Continuous Positive Airway Pressure (CPAP), a specialized machine that prevents negative interphalangeal pressure; however, the low patient adherence to using CPAP greatly diminishes its efficacy.11,12 Mandible positioner appliances, also known as OAs, are being used to treat mild to moderate OSA instead of CPAP. OAs work by moving the mandible anteriorly, which opens the pharynx, allowing for unobstructed breathing. 13 OAs can be made in a number of different ways.

Traditionally, a patient would present with a previously completed sleep study, graded with mild to moderate OSA. Based off the patient’s subjective comfort and sleep score, patients would be moved 60-70% of their maximal protrusion. This would be completed by using a george gauge bite registration and impressions of the teeth to make models for OA production at a dental lab. The fabricated OA would then be inserted into the patient’s mouth, and protrusion would be adjusted through adjustable wings or screws. Typically, patient subjective scores would be used to see if the OA is working. Some clinics could take it a step further and perform another level III study to see if the OA is properly working, if they had access to a sleep lab. However, the MATRx plus theragnostic study is able to check the response to an OA before fabrication. The MATRx plus machine will move the patient’s lower jaw in a dynamic fashion on the first study night to establish a protrusive target and a response profile. The subsequent study nights will set the jaw to the most appropriate position for sleep apnea reduction and record the patient’s sleep data. From the data collected during all of the theragnostic study nights, the MATRx plus makes a prediction as to whether the patient will benefit from an OA.

Though OAs are becoming more common for OSA treatment, some patients are non-responders. 14 Different studies have stated a range between 50.3% to 71% of people respond to OA with mild to moderate OSA. 15,16 Though there are some indicators that patients will respond – patients with positional dependent OSA, lower BMI, and mild to moderate OSA – there are few methods to proactively check OA eligibility. There are two current methods to check OA eligibility: one is the MATRx in-lab system using a remote controlled mandibular positioner – a specialized machine that repositions the mandible under polysomnographic observation; and the second is the MATRx plus, the only take-home sleep device that works during a theragnostic study using a CCMP (computer controlled mandibular positioner). This allows for confident OA treatment. 14

With CBCT technology, an exact fit OA is made by milling in accordance to the CBCT information and the CEREC optical scan data. This creates a custom OA that ensures a tight fit and comfort. SICAT has an OA called OPTISLEEP that follows this protocol of OA creation, allowing for a custom fit for patients. The appliance uses firm plastic bands that link the maxilla to the mandible. The appliance will come set to the patient’s effective target protrusive position, determined during the theragnostic study. The appliance also comes with bands of different length that can be used to change OA positioning for greater comfort or response if necessary.

The use of both CBCT and MATRx plus in tandem is a fresh approach to treat patients that suffer from previously undiagnosed OSA. Using the Sirona/SICAT CBCT system and OPTISLEEP technology, patients will be treated with a computer-generated OA. As well, with the new partnership between Dentsply Sirona and Zephyr Sleep Technologies, the MATRx plus will be used to gauge whether a patient will be eligible for OA treatment and how far the mandible will need to be moved forward for optimum treatment. This integration between the two cutting edge technologies will allow for a novel approach in treating OSA with OA.

An In-Depth Case Report
Patient S.H. was previously diagnosed with mild/moderate obstructive sleep apnea and currently using a CPAP machine. S.H. is 34 years old. S.H. was previously tested for sleep apnea at an accredited sleep medicine facility and had an AHI of 8. Because of the cumbersome size of the CPAP, S.H. wanted to see if an OA could treat her OSA. We discussed the MATRx plus and S.H. decided to move forward with the testing.

Our first workflow step was to take a CBCT scan of the patient’s airway. This gave us, and the patient, a visual representation of her airway. We scanned S.H.’s throat with the Sirona Orthophos SL (Figs. 4-5) and made a 3D rendering in SICAT Air (Fig. 6). We segmented her airway and created a 3D rendering showing her minimum cross-sectional area of 106 mm^2. It also coloured her airway giving a 3D representation of where her airway restrictions are.

Fig. 4

Orthophos SL.

Fig. 5

Orthophos SL.

Fig. 6

SICAT 3D rendering.

In order to run a MATRx plus study, the patient first needed a patient profile made at zephyrportal.com (Fig. 7). The diagnostic study was chosen from the study profile menu. Once the patient has an active study, the patient was selected on the MATRx plus supplied tablet. The patient needed to confirm their birthdate upon study start for all sleep studies. We made S.H.’s profile and chose a theragnostic study from the menu. To run a theragnostic study, the patient’s Max protrusion, Min retrusion, and habitual bite were needed.

The MATRx plus theragnostic study was a two to three-night study. In order to run the study, a temporary mouthpiece needed to be custom made for the patient (Figs. 8-9). Completed by using one of the MATRx plus titration trays and a fast set polyvinyl bite registration material (Dentsply), a custom mold was made for the patient’s mouth. Once the patient’s trays were made, they were asked to move their jaw to minimum retrusion, habitual bite, and maximum protrusion, all of which were recorded and entered for study initiation. S.H.’s jaw range of motion measurements were 1.5, -3, and 9 millimeters for habitual bite, min retrusion, and max protrusion respectively. The first night was a dynamic night where the patient’s mandible was constantly being repositioned throughout the night. Night two was static, where the MATRx plus moves to the targeted position calculated during the dynamic study night, and refines the position only as needed. The MATRx plus may recommend a third study night, in a select number of patients, to test a lower target protrusive position.

Fig. 7

Zephyr Portal quick menu.

Fig. 8

Mandibular positioner before insertion.

Fig. 9

Mandibular positioner after insertion.

S.H. completed their exam and came back into the office. The raw reports displayed two completed nights with no issues, as can be seen by Fig. 10. It was found through the MATRx plus study summary report that S.H. was most responsive at 2.6 mm from neutral position (Fig. 11). This represented a 35% protrusive movement in order to treat her OSA. The temporary mouthpiece was then locked at this position and another 3D CBCT scan was taken with the mouthpiece inserted (Fig. 12). Using the CEREC optical scanner, optical scans were then completed and imported into SICAT Air as a .ssi file and merged with the mouthpiece CBCTs (Fig. 13). When merging was complete, the whole file was sent to the SICAT Lab, in Germany, for OPTISLEEP fabrication.

While the patient waits for their OPTISLEEP appliance to be fabricated, they are able to use the MARx plus mouthpiece as a temporary OA (Fig. 14). A transitional device (TD) clip with pins was used to fix the mouthpiece into the target protrusive position determined from the theragnostic study. We also used the protruded 3D CBCT upper airway rendering as a way to show patients how the mouthpiece is treating their OSA.

Fig. 10

MATRx plus Report.

Fig. 11

MATRx plus Report.

Fig. 12

3D rendering at the MATRx plus target protrusive position.

Fig. 13

CEREC scanned Arches.

Fig. 14

Mouthpiece locked in place with the TD clip.

Once we received the OPTISLEEP appliance (Figs. 15-16) we called back S.H. and had her try it for fit and comfort (Figs. 17-20). S.H. confirmed that her OPTISLEEP appliance was comfortable and left without any additional questions. A follow up appointment was done at one week and two weeks to ask about her sleep quality and to check appliance fit. One-month after S.H. received her OPTISLEEP, we ran a MATRx plus study for therapeutic follow-up. This was completed by creating a baseline study on the patient’s profile at zephyrportal.com. The patient was then sent home with the MATRx plus system and all required sensors. This was a one-night study and recorded the patient’s AHI and oxygen desaturation with the OPTISLEEP set at the target protrusive position predicted during the theragnostic study. The results came back confirming good OA position as the AHI was a 1.2 (Fig. 21) consistent with the theragnostic study results. The study was reviewed by one of Zephyr Sleep Technologies sleep physicians, who confirmed that the OPTISLEEP therapeutic appliance was successfully treating the patients OSA.

Fig. 15

OPTISLEEP.

Fig. 16

OPTISLEEP.

Fig. 17

Inserted OPTISLEEP.

Fig. 18

Inserted OPTISLEEP.

Fig. 19

Pre-OPTISLEEP, side profile.

Fig. 20

Inserted OPTISLEEP, side profile.

Fig. 21

OPTISLEEP inserted MATRx plus baseline study for therapeutic follow-up.

Discussion
The workflow using Dentsply Sirona’s Orthophos SL Three-Dimensional Cone Beam Computed Tomography and SICAT Air’s imaging software with the MATRx plus baseline and theragnostic sleep studies allows for a very smooth workflow for diagnosing and treating obstructive sleep apnea. The benefits of this system is four parts: 1) Improved screening; 2) In office approach to diagnosis with a portal connection to a certified sleep physician; 3) A predictive value in determining if a patient is a responder prior to oral appliance treatment using a computer controlled mandibular positioner; and, 4) Minimizing the patient’s protrusive position as we have a means of measuring optimal therapeutic target to minimize temporomandibular joint strain. Having this system in your office will allow for therapeutic follow-up testing as well, allowing you to see if the oral appliance therapy is effectively treating their obstructive sleep apnea or if they need to be titrated further. OH

Oral Health welcomes this original article.

Disclosure
Dr. Michael Parchewsky is a beta tester for Dentsply Sirona and a key opinion leader for Zephyr Sleep Technology.

Contact Info
Suite 210, 530-8th Avenue, SW, Calgary, Alberta, Canada T2P 3S8.

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About the Authors
Dr. Parchewsky completed an Honors degree in Physiology from the University of Alberta and a Doctor of Dental Medicine degree from the University of Saskatchewan including surgical extern programs at the University of Florida and the University of Texas Health Science Center. Completing a one-year Oral and Maxillofacial Surgery Fellowship at the Albert Einstein College of Medicine in New York, Dr. Parchewsky provides oral surgery and IV sedation procedures in multiple dental offices. His main focus is full mouth implant rehabilitation cases and guided procedures. Dr. Parchewsky is a founding member of the Alberta Dental Society of Anesthesiology and is a beta tester for Dentsply Sirona. Dr. Parchewsky has joined Zephyr Sleep Technology as a key opinion leader. Dr. Michael Parchewsky: omfsdentist@gmail.com; http://www.terradentalcare.com/

Mr. McKercher obtained a Bachelor of Science with a minor in public health from the University of Calgary, Ross was born and raised in Calgary. With a background in clinical research, Ross has worked on multiple randomized controlled studies with the Orthopaedic Trauma Research Team in Calgary. Having helped publish many studies, he is well versed in research and he is trained to run prospective cohort studies. Ross McKercher: parchestudyclub@gmail.com; http://www.terradentalcare.com/