By Sree Roy
When obstructive sleep apnea patients are prescribed CPAP, key settings that impact outcomes are pressure and mask fit. New research now similarly sheds light on analogous fabrication settings that impact the efficacy of custom oral appliances. The research abstract, published in the July 2022 issue of the Journal of Dental Sleep Medicine, also goes a step further to provide a relatively inexpensive option for optimizing the settings before ordering custom oral appliances.
The study won the clinical research award at the 2022 American Academy of Dental Sleep Medicine Annual Meeting, the fourth such award this team of investigators has received since 2019 as a result of their effort to validate an oral appliance therapy (OAT) protocol that manages healthcare costs by not referring patients for custom oral appliances unless they will demonstrate at least a minimal treatment response.
“We’ve heard repeatedly that physicians are reluctant to prescribe OAT because, unlike CPAP or positional therapy, there was not a way for the patient to undergo a trial to evaluate OAT efficacy before committing to a relatively large expenditure,” says Daniel Levendowski, MBA, first author of the abstract. “If we demonstrated that a trial oral appliance could achieve results equivalent to the custom oral appliance, then our OAT protocol would be validated.”
The new study builds on a study published in the Journal of Dental Sleep Medicine last year, which reported that a custom oral appliance fitted using a conventional dental protocol delivered inferior reductions in apnea-hypopnea index (AHI) as compared to a trial oral appliance protocol using Apnea Guard, a trial oral appliance by company Advanced Brain Monitoring, of which Levendowski is president and co-founder. The investigators speculated that the improved efficacy with the Apnea Guard was the result of several settings employed during its protocol.
As Levendowski describes it, the first is selecting the vertical dimension of occlusion (VDO), the distance between the upper and lower teeth imposed by the oral appliance with the jaw closed and stationary. “VDO impacts the amount of room that the oral appliance provides for the tongue based on tongue scallop and sex,” he says. “Males need more VDO because their airways are longer relative to females.” The second is identifying a target protrusion that optimizes the oral appliance’s jaw-forward positioning of the mandible. The third is controlling vertical mouth opening so protrusion is consistently maintained. That is, “the mouth doesn’t drop open when sleeping supine,” he says.
The goal of the new study was to demonstrate that by directly transferring the Apnea Guard vertical dimension of occlusion and protrusion to the custom oral appliance, as well as controlling for vertical mouth opening, its inferiority would be resolved. The team analyzed 51 patients and the results confirmed this hypothesis.
The Apnea Guard AHI also predicted those with a custom oral appliance AHI reduction of more than 50% (odds ratio=0.91; 95%CI: 0.83-1.00; P<0.05) and both an AHI reduction greater than 50% and an AHI less than 10 (odds ratio=0.77; 95%CI: 0.67-0.88; P=0.0002).
“Use of an inexpensive trial appliance to identify responders should provide clinicians greater confidence in prescribing OAT as a first-line therapy,” Levendowski says.
According to Levendowski, the protocol for VDO selection can be applied by a dentist without using an Apnea Guard by evaluating tongue scallop (similar to taking a Mallampati score). “Dentists can also encourage use of vertical elastics when prescribing the Herbst OA or select OAs that limit vertical mouth opening (eg, Prosomnus IA, Somnomed Avant, etc.),” he says. “Dentists typically tried to keep VDO as minimal as possible and allowed for vertical mouth opening due to the belief that these settings would improve comfort. The [new] study results demonstrated that these functional settings, which can be applied without use of the ApneaGuard, are critical to optimized oral appliance outcomes.”
In the new study, five patients at risk for temporomandibular joint (TMJ) complications were excluded, which was less than 7% of study patients fitted with a custom oral appliance. “We identified those at risk for TMJ inflammation and initiated protrusion conservatively; however 93% of the patients were fitted at the Apnea Guard 70% protrusion and none reported any side effects at this target setting, and the patients did not need to come back to the dentist for additional OA adjustments.
“Dentists are taught to treat every patient conservatively under the assumption that every patient is at risk of TMJ inflammation. But by doing so it takes patients longer to reach their final protrusion by as much as 120 days.”
The team is now conducting a trial in Canada, in which the recommendation for treatment with an oral appliance, positional therapy, or both is guided by software that applies rules derived from the team’s cost-containment analysis.
Sree Roy is editor of Sleep Review.
Levendowski D, Sall E, Beine B, et al. Selection of custom oral appliance fabrication settings impact treatment efficacy. JDSM. 10 Jul 2022;9(3):31 (Abstract #014).