If you wear an oral appliance for sleep apnea and notice your back teeth no longer touch the way they used to, you’re not imagining it — and you’re not alone. A new retrospective study looked at exactly how often this happens and what factors might predict it.
Key Points
- A posterior open bite (POB) is a gap between the back teeth that develops during long-term use of an oral appliance for obstructive sleep apnea (OSA).
- In a retrospective study of 96 patients, POB occurred in 16.7% of cases, typically detected around 3.5 years into treatment (PMID 42714694).
- Certain skeletal measurements (including the SNB angle, which describes lower jaw position) were associated with POB in simple analysis, but no factor remained a significant independent predictor once other variables were accounted for.
- Because no reliable predictor has been identified, routine dental monitoring throughout appliance therapy is the current, evidence-based approach — not pre-treatment risk screening.
- This is a single retrospective study; prospective research with larger cohorts is needed before skeletal risk factors can be used clinically.
What is a posterior open bite, and why does it happen?
An oral appliance (OA) for obstructive sleep apnea works by holding the lower jaw in a forward position during sleep, which helps keep the upper airway open. This mandibular positioning is repeated nightly, often for years. Over time, in some patients, this sustained forward posture is accompanied by a gradual change in how the back teeth meet — a gap opens between the upper and lower molars and premolars when the front teeth are still in contact. This is called a posterior open bite (POB).
POB is a recognized long-term dental side effect of oral appliance therapy, distinct from short-term morning bite changes that resolve after removing the device. It reflects a more lasting shift in tooth position or jaw relationship.
How common is it, and how is it diagnosed?
The retrospective study reviewed 96 patients undergoing oral appliance therapy for OSA and found posterior open bite in 16.7% of the cohort (PMID 42714694). Detection occurred at a variable point in treatment, averaging roughly 3.5 years after therapy initiation — underscoring that this is a slow, cumulative change rather than an early or predictable event.
POB is identified through routine clinical dental examination: checking whether the posterior teeth make contact when the patient bites down naturally, without the appliance in place. There is no single imaging test required for diagnosis — it is a clinical occlusal finding, which is why regular follow-up visits matter.
What did the research find about who is at risk?
This is the question the study set out to answer, and the results are instructive precisely because they show what the current evidence does not support.
In univariate analysis — looking at one factor at a time — certain cephalometric (jaw X-ray) measurements, including the SNB angle (a measure describing how far back or forward the lower jaw sits relative to the skull base), showed an association with POB development. However, when the researchers used multivariable analysis — accounting for multiple factors simultaneously — none of these skeletal parameters remained statistically significant independent predictors (PMID 42714694).
In plain terms: individual measurements looked interesting on their own, but once other variables were controlled for, the study could not confirm that any single skeletal trait reliably predicts which patients will develop POB.
| Question | What the evidence shows |
|---|---|
| How often does POB occur? | 16.7% of the 96-patient cohort (PMID 42714694) |
| When does it typically appear? | Variable; average ~3.5 years after starting therapy |
| Do skeletal measurements (e.g., SNB) predict it? | Associated in single-factor analysis, not confirmed in multivariable analysis |
| Can patients be screened beforehand for risk? | Not currently — no validated predictor exists |
| What is the recommended response? | Systematic, ongoing occlusal monitoring during therapy |
Which approach is right for me?
Because no skeletal or dental feature has been shown to reliably predict who will develop a posterior open bite, the current evidence does not support selecting or excluding patients from oral appliance therapy based on baseline cephalometric measurements. Instead, the study’s authors point toward systematic occlusal monitoring for all patients throughout the course of therapy — meaning your bite should be checked at scheduled follow-up visits for as long as you use the device, not just at the start of treatment.
If a posterior open bite is identified, the clinical response depends on its severity and your specific occlusal findings, and should be discussed directly with your treating dentist or orofacial pain specialist. Oral appliance therapy remains a recognized treatment for OSA; the presence of this finding in the literature is a reason for monitoring, not a reason to assume treatment failure or to stop therapy without evaluation.
When should I see a specialist?
Consider a dental evaluation if:
- You’ve been using an oral appliance for OSA for a year or more and haven’t had a recent bite check.
- You notice your back teeth touching differently than before, or a visible gap when you bite down without the appliance.
- Your appliance no longer seems to fit the way it once did.
A specialist trained in dental sleep medicine can assess whether occlusal changes are occurring and determine next steps.
For referring providers
This retrospective cohort study (n=96) reports a 16.7% incidence of posterior open bite among OA-treated OSA patients, with detection occurring at a mean of approximately 3.5 years post-initiation (PMID 42714694). Univariate analysis identified associations between POB and select cephalometric parameters, including SNB angle; however, multivariable modeling did not identify statistically significant independent predictors. Given the retrospective design and absence of validated risk stratification tools, the authors recommend systematic occlusal monitoring throughout OA therapy rather than baseline cephalometric screening for patient selection. Larger prospective studies are needed to characterize skeletal and dental risk factors with greater precision. Referrals for baseline and periodic occlusal assessment in OA-treated patients are appropriate regardless of cephalometric profile.
This article summarizes findings from a single retrospective study and is intended for general information. It is not a substitute for individualized clinical evaluation.
An evaluation with our clinic is available for patients seeking assessment of oral appliance therapy or occlusal changes during treatment.
References
- Frequency and skeletal factors associated with posterior open bite during oral appliance therapy for obstructive sleep apnea: A retrospective study. Sleep & Breathing = Schlaf & Atmung. 2026. PMID: 42714694
