A patient diagnosed with moderate OSA sits in a dental chair. The patient is CPAP non-compliant and has been referred to a dentist credentialed in Dental Sleep Medicine for Oral Appliance Therapy.
One of the many decisions facing the dentist is OAT device selection. Does the dentist choose a familiar OAT device? Or is there something unique about a specific patient that suggests a different option? And what about one of the new OAT devices that has been recommended by a colleague? Is this the time to try something different?
OAT device selection matters. A review of the forty-two papers cited in the AADSM’s Clinical Practice Guideline for OAT efficacy reveals considerable variability in AHI improvement, ranging from 82% to 21% AHI improvement.1 Differences in OAT efficacy are reported in eight of the nine papers, amongst the forty-two, that directly compare two or more OAT devices. Further, the literature suggests variability in compliance, side effects, quality of life, and other generally accepted measures of OAT outcomes. Though differences in methodology and sample characteristics likely account for some of this variability, OAT device selection warrants important consideration.
This very same variability also represents opportunity; the potential for better OAT device design. What if an OAT device could facilitate more frequent AHI improvements in the 82% end of the spectrum? Or better comfort and compliance rates? Or mitigate the risk of tooth mobility, and other side effects? Or more reliable, predictable, clinical performance? What might this mean for patients, the dental practice and the Dental Sleep Medicine industry? Or how it influences a dentist’s OAT device selection process?
The Quest for Better OAT
In early 2017 ProSomnus Sleep Technologies arranged a meeting of two dozen leaders in dental sleep medicine with these types of questions in mind. The specific objective was to investigate opportunities to design a better continuous advancement (expansion screw style titration) OAT device, based on consensus input. What are the clinically relevant limitations of existing continuous advancement devices? And which of these opportunities for improvement, if adequately addressed by a new OAT design, might compel an expert dental sleep medicine expert to try a new OAT device?
“ProSomnus is about developing OAT devices that help dentists create better treatment experiences and outcomes for their OSA patients,” noted Len Liptak, ProSomnus CEO and Co-founder. “Collaboration with clinical experts is integral to our R&D process. It is a process that has, historically, worked very well in the dental and medical device industries.”
The group arrived at a handful of actionable insights. What follows are a few of the insights from the meeting, and some of the ProSomnus engineering solutions that led to the creation of the new ProSomnus [CA] Sleep Device.
Insight: Asymmetrical Titration
A chief concern that the group described, and an important opportunity for improvement upon traditional continuous advancement OAT devices, is the concept of unwanted, asymmetrical, titration. What does unwanted, asymmetrical titration mean? Simply put, fifty turns of the expansion screw on the left side of the device usually does not express the same A/P titration as fifty turns of the expansion screw on the right. This often results in extra adjustments, appointments, and an overall increased challenge of controlling the case.
There are two main sources of asymmetrical titration errors: anatomical variance and fabrication variance. Anatomical variance is the acknowledgement that arch forms are rarely symmetrical. Arch forms vary from patient to patient, from left side to right. These natural, anatomical, variances result in different A/P titration when an expansion screw is adjusted. For example, if the right side of the arch presents a 29-degree angle, 6.0mm of expansion screw displacement will express 5.3mm of A/P advancement. However, if the left side of the arch presents a 14-degree angle, 6.0mm of expansion screw displacement will express 5.8mm of A/P advancement, a 0.5mm difference between the left and right.
Limitations of the traditional, artisanal fabrication method for OAT devices is the second source of asymmetrical titration errors. It is challenging for a technician to embed each expansion screw in perfect symmetry with respect to the A/P titration path, particularly when the anatomy itself is likely not perfectly symmetrical. Expansion screw assembly errors in the X, Y and Z dimensions result in three-dimensional errors that make it challenging to achieve the target A/P location.
Figure 1: OSA Efficacy Studies Chart
Figure 2: ProSomnus [CA] Device
ProSomnus Solution: Fiducial Markings
To eliminate the need to count, record and communicate turns of the expansion screw during adjustments and to compensate for the aforementioned A/P titration asymmetries, fiducial markings are scored into the occlusal surface of the ProSomnus [CA] splint. The new fiducial markings feature corresponds to the true A/P titration, and not how far the screw has been adjusted. ProSomnus automatically calculates the trigonometry for each fiducial marking to compensate for the curvature of each side of each arch. In other words, a +1.0mm adjustment according to the fiducial marks relates to +1mm of true, anterior/posterior titration.
Figure 4: Fiducial Markings
Insight: Expansion Screw Assembly Breakage
The group reported that existing continuous advancement OAT devices are prone to breakage in the expansion screw assembly region. The titration mechanisms of existing continuous advancement OAT devices are ostensibly lever arms. Cantilever forces generated during routine OAT usage are amplified by the traditional lever arm design. The stress from the normal intraoral forces associated with OAT are concentrated toward the distal regions of the titration mechanisms.
As a result, traditional continuous advancement OAT devices can break more frequently than is desirable. Breakage often results in a series of clinical and therapeutic inefficiencies, not to mention the potential for the patient being out of treatment until a device is repaired or replaced.
ProSomnus Solution: Linear Guide
To address the concerns of asymmetrical titration and breakage, ProSomnus [CA] features a 3-dimensional channel machined into each side of the splint called a Linear Guide. The patent pending Linear Guide ensures predictable, symmetrical, advancement and mitigates the cantilever forces that are associated with breakage.
The expansion screw is embedded into a CAD designed engineered pocket that is oriented to the Linear Guide, which are both aligned to the simulated A/P titration path. This innovation is designed to both strengthen the expansion screw assembly and provide a precision engineered, controlled titration experience.
“The ProSomnus [CA] Sleep and Snore device uses a patent pending precision advancement mechanism designed to remove the guesswork out of protruding a patient’s mandible,” added Dave Kuhns, VP Technology and ProSomnus Co-founder. “The [CA] uses a proprietary approach to ensure that adjustments are symmetrical, aligned to true anterior/posterior protrusion, and easy to monitor.”
Figure 5: Linear Guide
Insight: Limited Titration Range
Occasionally OSA patients require more than the 5 or 6mm of displacement offered by a traditional expansion screw style OAT device, though most patients are treated within 3mm of the target position. Getting additional expansion is challenging, and often requires a complete reset of the device at a new target position. This process is time consuming, expensive, and might adversely impact the patient experience.
ProSomnus Solution: Enhanced Titration Range
To address the occasional need for additional titration range, the new ProSomnus [CA] device offers +12.0mm of total adjustment range. This is achieved by providing a second lower arch with 5.0mm of advancement, when needed, on demand, at no additional charge.
The additional 5.0mm advancement arch is made using the digital records on file, and the company’s patented method for simulating titration. No reset is required. No additional impressions or bites are required. The patient does not need to go without their device for any period of time.
Figure 6: ProSomnus [CA] Device Titration Range
Insight: From Side Effects to Bio-Gunk
The group also discussed a series of opportunities for improvement. Unwanted tooth movement, bulk and discomfort, device not matching the provided bite, minimization or elimination of metal, bio-gunk buildup, and limited customization options were amongst some of the more frequently mentioned areas that could be improved.
ProSomnus Solution: Precision Manufacturing and Engineered Materials
Though ProSomnus [CA] might not address every continuous advancement OAT device insight generated by the group, many of the additional insights are addressed by the foundational manufacturing technologies and materials utilized by ProSomnus. For example, there are indications of better therapeutic results,2 robust compliance and nightly usage,3 that the retainer-like fit of ProSomnus device splints are associated with a reduction in tooth mobility,4 and indications of reduced bio-gunk build-up due to the reduced porosity of the material used by ProSomnus.5
“The challenge for the [CA] program was to design a device that addresses the opportunities that leading dentists identified about traditional expansion screw devices while satisfying the comfort, control and overall performance characteristics that dentists expect from a ProSomnus device,” noted Sung Kim, VP Engineering and ProSomnus Co-founder. “We applied ProSomnus’ forward engineering approach to the key inputs identified by leading dentists.”
Back to the patient with moderate OSA who is waiting, or perhaps snoring, in the dental chair. The dentist reaches for a prescription pad and considers the OAT device options, and what is best for the patient. Perhaps this is the time to try, firsthand, if the new OAT device creates a better experience for the dental practice and the patient.
Special Note: ProSomnus Sleep Technologies would like to thank the leading dentists who participated in our R&D programs. The ProSomnus [CA] Device is cleared by the FDA, and currently being used to treat hundreds of patients across multiple dental practices in the United States and Canada.
- Ramar K, Dort LC, Katz SG, Lettieri CJ, Harrod CG, Thomas SM, Chervin RD. Clinical practice guideline for the treatment of obstructive sleep apnea and snoring with oral appliance therapy: an update for 2015. Journal of Dental Sleep Medicine 2015;2(3):71– 125.
- Remmers JE, Topor Z, Grosse J, Vranjes N, Mosca EV, Brant R, Bruehlmann S, Charkhandeh S, Jahromi SA. A feedback-controlled mandibular positioner identifies individuals with sleep apnea who will respond to oral appliance therapy. J Clin Sleep Med. 2017;13(7):871–880.
- Accepted for Publication: Hu J, Liptak L. Evaluation of a new oral appliance with objective compliance recording capability: a feasibility study. Journal of Dental Sleep Medicine. 2018;5(2):XX–XX.
- Hu J. Minimizing Side Effects: A Retrospective Case Series Analysis of Tooth Movement in Oral Appliance Therapy. Dental Sleep Practice 2018; March.
- Gelb M. Say No to Bio-Gunk! Dental Sleep Medicine Insider Magazine 2018; March: 6-8.