This page provides an independent statistical analysis and educational interpretation of publicly reported results. ClinicalTrials.gov provides the official trial registry record. Numerical trial results on this page are restricted to the results posted in the ClinicalTrials.gov record; calculations added by Clinical Biostats are labelled as such.
1. Trial at a Glance
This page covers the registry results for Temporomandibular Disorder (TMD) Pain in Response to Jaw Advancement in People With TMD and Obstructive Sleep Apnea (NCT02685202), a na na study. The primary outcome is Change in the Weekly Mean Pain Index Score.
| Feature | Registry value |
|---|---|
| ClinicalTrials.gov identifier | NCT02685202 |
| Phase | NA |
| Condition | Myalgia, Apnea, Obstructive Sleep |
| Allocation | Not applicable (single group) |
| Design model | Single Group |
| Masking | None (open label) |
| Enrollment | 9 |
| Arms in the primary outcome | n/a |
| Lead sponsor | University of North Carolina, Chapel Hill |
| Results posted | Yes |
2. Clinical Question
Population
Adults with painful temporomandibular disorder (TMD) and comorbid mild to moderate obstructive sleep apnea (OSA). The registry description specifies an apnea-hypopnea index of 5 or higher and below 30. The registered enrollment is 9.
Intervention
Mandibular advancement splint (MAS) therapy. The oral appliance repositions the mandible forward and is described in the registry as standard care for mild or moderate OSA. The study description planned treatment over 16 weeks.
Comparator
There was no comparison group. This was a single-group study, so the registry does not describe a concurrent group receiving a different treatment or no treatment.
Primary question
How does the weekly mean TMD pain index change from baseline to 16 weeks among adults with TMD and OSA receiving MAS therapy? The registry identifies this as the primary outcome, but says pain-diary information could not be obtained and the outcome data are unavailable.
3. Trial Design
This was an interventional, single-group study of mandibular advancement splint therapy for adults with painful TMD and OSA. The registry describes the intended population as having mild to moderate OSA, with an apnea-hypopnea index of 5 or higher and below 30. The intervention was an oral appliance that repositions the mandible forward. The registry describes MAS therapy as standard care for mild or moderate OSA, while stating that its effect on TMD pain in people with OSA was unknown.
The study description says participants were to receive therapy over 16 weeks, with the primary pain measure assessed at baseline and 16 weeks. It also describes weekly pain monitoring during the observation period. The registry lists enrollment of 9, while its brief description refers to 12 intended participants. The record does not explain the difference. Study status is terminated; the recorded start is 2016-03 and primary completion is 2017-03.
There was no comparison group, and the allocation is listed as NA. Consequently, the study is not a randomized comparison of treatment strategies. Any within-participant change would have been observed over time during therapy, without a concurrent group to help distinguish treatment-associated change from other influences. No protocol details beyond those stated in the registry record, such as the treatment schedule or rules for adjusting the appliance, are reported in the registry record.
The investigators’ stated expectation was that painful TMD symptoms would reduce as MAS therapy reduced OSA severity. This is a study hypothesis, not a reported finding. Although the registry lists changes in the apnea-hypopnea index and Epworth Sleepiness Scale score as secondary outcomes, numerical results for those measures are not reported in the registry record.
4. Participant Flow and Accounting
The registry reports how participants moved through each stage of the study. All counts below are exactly as posted; missing counts are not inferred from other stages.
Overall Study
| Stage | Mandibular Advancement Splint |
|---|---|
| STARTED | 9 |
| COMPLETED | 0 |
| NOT COMPLETED | 9 |
Reasons for not completing this period:
| Reason | Mandibular Advancement Splint |
|---|---|
| Lost to Follow-up | 9 |
Analysis population for the primary outcome, as defined in the registry: No participants could be reached to obtain pain symptom diary information; therefore, data for this outcome measure are unavailable.
5. Baseline Characteristics
The table reproduces the baseline characteristics posted in the registry, which describe the participants analysed at baseline and help show whether the randomized groups were comparable.
| Characteristic | Unit | Mandibular Advancement Splint |
|---|---|---|
| Participants analysed | 9 | |
| Age, Categorical: <=18 years | Participants | 0 |
| Age, Categorical: Between 18 and 65 years | Participants | 9 |
| Age, Categorical: >=65 years | Participants | 0 |
| Age, Continuous | years | 53. (SD 2.3) |
| Sex: Female, Male: Female | Participants | 9 |
| Sex: Female, Male: Male | Participants | 0 |
| Race (NIH/OMB): American Indian or Alaska Native | Participants | 0 |
| Race (NIH/OMB): Asian | Participants | 0 |
| Race (NIH/OMB): Native Hawaiian or Other Pacific Islander | Participants | 0 |
| Race (NIH/OMB): Black or African American | Participants | 0 |
| Race (NIH/OMB): White | Participants | 9 |
| Race (NIH/OMB): More than one race | Participants | 0 |
| Race (NIH/OMB): Unknown or Not Reported | Participants | 0 |
| Region of Enrollment: United States | participants | 9 |
6. Primary Endpoint
The registry lists the primary outcome as Change in the Weekly Mean Pain Index Score, measured over Baseline, 16 weeks.
| Element | Registry entry |
|---|---|
| Result type | N/A |
| Measure of spread | not applicable |
| Unit | not stated |
| Endpoint classification | not reduced to a single comparison |
The primary endpoint is change in the weekly mean pain index score from baseline to 16 weeks. It is intended to represent facial pain over time rather than pain at a single moment. Participants were to record daily pain intensity and the percentage of the waking day with facial pain in a symptom diary. The daily pain index is described as the product of those two ratings; weekly values are described as arithmetic means of daily index values over the preceding 7-day period. The registry describes the weekly mean pain index on a 0-10 numeric rating scale.
A repeated diary measure can capture both pain intensity and how long pain is present, and weekly averaging can represent the pattern over several days rather than relying on a single report. Comparing baseline with the planned 16-week assessment was intended to characterize the course of TMD pain during MAS therapy. That makes the endpoint relevant to the study’s question, but it does not by itself establish that any observed change was caused by the appliance, particularly without a comparison group.
Most importantly, the registry states that participants could not be reached to obtain pain symptom diary information. It therefore reports that primary outcome data are unavailable. No baseline score, follow-up score, change estimate, or uncertainty measure for this endpoint is reported in the registry record.
7. Why No Re-analysis Is Shown
8. Statistical Interpretation
The central statistical finding is an absence of an analyzable primary outcome, not an estimate showing whether pain increased, decreased, or stayed similar. The registry says that no participants could be reached to obtain pain symptom diary information and that data for the weekly mean pain index were unavailable. There is therefore no reported baseline-to-16-week change, and the direction or size of any change cannot be established from the posted results.
The registered enrollment is 9. The brief study description refers to 12 adults, but the record does not explain why those figures differ. Neither figure can substitute for the number of participants with usable primary endpoint data: the registry explicitly says that the pain-diary outcome data are unavailable. The number with usable data for secondary outcomes is not reported in the registry record.
Even if a before-and-after pain estimate had been available, a single-group design would describe change over time among participants, not isolate the effect of MAS therapy. Pain can vary over time, and other influences could coincide with treatment. A concurrent comparison group can help address some of these issues; this study had none. The investigators’ expectation that TMD symptoms would reduce as OSA severity reduced should therefore be read as a rationale for the study, not as an observed result.
The registry lists secondary outcomes for apnea-hypopnea index and Epworth Sleepiness Scale score, but numerical results for them are not reported in the registry record. The adverse-event record lists 9 participants at risk, with 0 serious adverse events, 0 other adverse events, and 0 deaths. Those counts describe what is recorded; they do not provide a precise estimate of event risk, especially when enrollment is limited and the study was terminated. The reasons for termination and the duration or completeness of safety follow-up are not reported in the registry record.
No effect estimate, confidence interval, or p-value for the primary outcome is reported. A confidence interval would ordinarily show the range of values compatible with the data under a specified method; without outcome data, such a range cannot be interpreted for pain change. Likewise, there is no reported statistical test of the primary endpoint. The record lists 0 analyses, and details of an analysis plan are not reported in the registry record. Thus the available record supports describing the study design, missing primary outcome, and posted safety counts, but not drawing a quantitative conclusion about change in TMD pain or the intervention’s effect.
9. Statistical Methods Explained
Statistical interpretation begins with the design and the outcome information that is actually available. This study is registered as single-group, with no comparison group. Its planned primary assessment compares the weekly mean pain index at baseline and 16 weeks. Such a comparison would be a within-participant description of change over time, rather than a randomized treatment contrast. Since the primary diary values are unavailable, even that descriptive change cannot be estimated from the registry record.
What a within-participant change would describe
In general, a pre-treatment and follow-up comparison asks whether the measured outcome differs across time for participants who were observed at both occasions. Repeated measurements can reduce the influence of stable differences between participants, because each participant contributes measurements at more than one time. However, change over time is not automatically attributable to treatment. Without a comparison group, natural variation, changes in circumstances, and other concurrent influences cannot be separated from change associated with treatment. This is a general limitation of interpreting an uncontrolled before-and-after observation, not a result specific to the pain scores in this study.
Here, the registry’s outcome definition uses daily diary ratings to derive a weekly mean. The daily pain index combines pain intensity with the percentage of the waking day that facial pain was present, and the weekly measure averages daily values over the preceding 7-day period. Repeated diary collection was intended to capture a broader pain pattern than an isolated rating. Yet a defined measurement procedure is not the same as an observed result: the record says the diary information could not be obtained.
Estimates, uncertainty, and tests
In general, an estimate gives the magnitude and direction of a measured quantity, such as a mean change. A confidence interval expresses uncertainty around an estimate, using a method that depends on the data and assumptions. A p-value, when calculated, evaluates how compatible the observed data are with a specified null model; it does not measure the size or importance of an effect. These concepts require analyzable outcome data. The registry does not report a primary outcome estimate, confidence interval, or p-value, so none can be interpreted for the pain endpoint.
With no endpoint values, there is also no basis for assessing the observed variability of pain scores, the distribution of changes, or whether assumptions for a particular statistical procedure were reasonable. The statistical model, any covariate adjustment, handling of repeated measurements, and approach to outlying or incomplete diary entries are not reported in the registry record. It would be inappropriate to infer those choices from the endpoint definition alone.
Over-dispersion and count outcomes
As a general statistical concept, over-dispersion occurs when count data vary more than a model’s assumptions allow. It can make uncertainty estimates too small if a model assumes less variability than the data contain. This is relevant to some analyses of event counts, but the registry record does not report an event-count model or a statistical analysis of adverse events. The posted adverse-event figures are counts, not an inferential comparison.
The listed secondary measures are changes in apnea-hypopnea index and Epworth Sleepiness Scale score. The registry record does not give their observed values, estimates of change, or analysis methods. It therefore does not support describing a statistical relationship between change in OSA measures and change in TMD pain. Nor does it report whether the investigators planned a joint or separate analysis of these outcomes.
Planning calculations and observed evidence
General sample-size calculations can illustrate how many participants might be needed under stated assumptions about a target effect, variability, allocation, and statistical testing. Such calculations are planning illustrations, not observed evidence and not a substitute for an estimate from collected outcomes. The registry record does not report the study’s own sample-size justification or statistical plan. Since the primary outcome data are unavailable, there is no observed pain effect in the registry results to interpret as evidence of benefit or harm.
Details of any interim analyses, stopping boundaries, or prespecified decisions based on accumulating results are not reported in the registry record. The study status is terminated, but the record does not state the reason or connect termination to a statistical criterion. It is therefore not possible to infer whether termination followed recruitment difficulties, operational circumstances, or a review of results.
Overall, the appropriate statistical reading is constrained: the registry supplies a design and an intended measurement strategy, but not usable primary outcome values or reported inferential analyses. General methods can explain what those analyses would ordinarily aim to quantify; they cannot fill in missing observations or establish what happened to participants’ pain.
10. Multiplicity, Missing Data and Analysis Populations
Multiplicity arises when several outcomes or statistical tests are examined, because repeated testing can increase the chance of finding an apparently notable result by chance. The registry lists a primary pain outcome and secondary outcomes for apnea-hypopnea index and Epworth Sleepiness Scale score. However, the analysis plan and any approach to multiplicity are not reported in the registry record. The record lists 0 analyses, and it does not report outcome-specific estimates or tests. No claim about adjustment, prioritization beyond the listed primary outcome, or interpretation across multiple tests can be made.
Missingness is decisive for the primary endpoint. The registry says participants could not be reached to obtain pain symptom diary information and that the outcome data are unavailable. It does not report when contact was lost, why participants could not be reached, whether any diaries were partly completed, or whether any imputation or other missing-data method was used. The amount and pattern of missingness for secondary outcomes are not reported in the registry record.
The analysis population is also not described. Although registered enrollment is 9 and the brief description refers to 12 intended participants, the record does not specify how many were treated, completed follow-up, or contributed data to each outcome. The distinction between all enrolled participants and participants with usable measurements is important for interpreting estimates, but the needed outcome-specific counts are unavailable. Protocol definitions for inclusion in analyses, exclusions, and handling of withdrawals are not reported in the registry record.
11. Safety Results
The registry reports serious adverse events as affected participants divided by participants at risk.
| Arm | Participants with serious adverse events | Participants at risk | Percentage |
|---|---|---|---|
| Mandibular Advancement Splint | 0 | 9 | 0.0% |
Deaths
| Arm | Deaths (participants affected of at risk) |
|---|---|
| Mandibular Advancement Splint | 0 of 9 |
Other (non-serious) adverse events
Participants with at least one non-serious event at or above the registry's 0% reporting threshold.
| Arm | Participants affected of at risk |
|---|---|
| Mandibular Advancement Splint | 0 of 9 |
The registry lists 9 participants at risk for both serious and other adverse events in the mandibular advancement splint group. It records 0 serious adverse events, 0 other adverse events, and 0 deaths. These figures are event counts in the registry record; they should not be read as proof that no adverse events could occur or that the intervention is free of risk.
When a study has limited enrollment, zero recorded events provide limited information about how frequently events might occur in a broader population. The registry does not report a comparator group, so the counts cannot be used to compare event experience under MAS therapy with another strategy. The record also does not state the duration or completeness of safety follow-up, the procedures for collecting adverse-event information, or why the study was terminated. Those details are not reported in the registry record.
The listed figures should therefore be interpreted narrowly: no serious events, other events, or deaths are recorded among the 9 participants listed as at risk. They do not resolve the unavailable primary pain outcome and do not establish a comparative safety profile.
12. What the Result Does, and Does Not, Mean
This study addresses a focused question: the course of TMD pain during mandibular advancement splint therapy among adults with both painful TMD and OSA. It has a defined primary measure, based on repeated daily pain records and intended to compare baseline with 16 weeks. The registry also identifies OSA-related secondary outcomes. These features indicate what the investigators intended to observe, but they do not establish what the outcomes were.
The primary pain data are unavailable because participants could not be reached to obtain diary information. As a result, the record does not show whether pain changed, the amount or direction of any change, or how precisely a change could be estimated. The secondary outcome values are not reported in the registry record either. The stated expectation that pain symptoms would reduce as OSA severity reduced remains a hypothesis, not an outcome supported by the posted results.
The single-group design also limits causal interpretation. If a change estimate were available, it would describe change over time in the treated group. Without a concurrent comparator, it would not separate change associated with the appliance from changes that might have occurred for other reasons. This distinction matters even when a study has careful outcome definitions and repeated measurements.
The record does report 9 participants at risk and no recorded serious adverse events, other adverse events, or deaths. Those counts should be read as a description of the registry’s safety entries, not as a precise estimate of risk or a comparison with another treatment. The registered enrollment differs from the 12 participants referred to in the brief description, and the reason for that discrepancy is not reported.
In practical statistical terms, the registry provides information about the study question, planned treatment period, and unavailable primary outcome, but not evidence that quantifies a change in TMD pain. It cannot support a conclusion about whether MAS therapy did or did not alter pain in this study. The absence of reported results is not evidence of no change; it means the relevant change cannot be evaluated from the posted record.
13. Why This Trial Matters Statistically
This trial is statistically informative as an example of the difference between a well-specified research question and an answerable analysis. The registry defines a population with painful TMD and OSA, a single intervention, a planned observation period, and a pain endpoint based on repeated symptom diary entries. Those elements describe what the study set out to examine. But an endpoint only informs readers when the corresponding measurements are available and reported.
The missing primary outcome demonstrates how participant contact and outcome collection are part of the evidence itself. If the diaries cannot be obtained, the planned change estimate cannot be calculated from those records. The registry does not identify the reason the information was unavailable or describe an alternative measurement method. Consequently, the limitation is not merely a lack of statistical significance: there is no reported pain estimate to test or quantify.
The single-group design also makes clear why descriptive change and treatment effect are different questions. Repeated measurements can characterize the course of symptoms during treatment, but a comparator is needed to help interpret whether that course differs from what might otherwise have occurred. The study had no comparison group, so even complete pre- and post-treatment observations would have required cautious interpretation.
Finally, the difference between registered enrollment of 9 and the 12 participants in the brief description, alongside unavailable diary data and termination status, underscores the value of clear reporting about participant flow and analysis populations. Such details help readers understand which observations underpin each result. The registry does not report those outcome-specific counts or the reason for termination. The result is a record that documents the intended question and important constraints, while leaving the primary statistical question unanswered.
14. Limitations
- The posted summary statistics are the only data these results rest on; patient-level data, full protocols and statistical analysis plans are not available.
- Recalculated results are simple, unadjusted calculations from posted summaries. They do not replace the sponsor's prespecified analysis.
Several limitations are specific to this study record. First, the primary endpoint depends on pain symptom diary information, but the registry says no participants could be reached to obtain that information. The outcome is therefore unavailable, and the record does not describe an alternative source of pain measurement. The timing, completeness, and reasons for the missing diary information are not reported in the registry record.
Second, registered enrollment is 9, whereas the brief description refers to 12 adults. The record does not explain this discrepancy or state how many participants began treatment, completed the observation period, or contributed to particular outcomes. The study is marked terminated, but the reason for termination is not reported in the registry record.
Third, there is no comparison group. This restricts interpretation to the planned course of outcomes during treatment and prevents a direct comparison with another approach. Allocation is listed as NA, and the study is identified as single-group rather than a randomized comparison.
Fourth, while the registry identifies secondary outcomes for apnea-hypopnea index and Epworth Sleepiness Scale score, their results are not reported in the registry record. Statistical methods, the analysis population, missing-data handling, sample-size justification, and any interim analyses are also not reported in the registry record. The safety entries list no recorded events, but details about follow-up and event collection are absent. Together, these gaps prevent a quantitative assessment of the primary question and limit interpretation of the study’s other outcomes.
15. Related Tutorials
16. Related Statistical Calculators
17. Sources
- ClinicalTrials.gov: Temporomandibular Disorder (TMD) Pain in Response to Jaw Advancement in People With TMD and Obstructive Sleep Apnea — NCT02685202.
- Registry record last updated 2017-11-14; status last verified 2017-10.
- Results first posted 2017-11-14.
- Data retrieved from ClinicalTrials.gov on 2026-11-09.
- Group sizes, means, event counts and sponsor-reported p-values are reproduced as posted. Effect estimates, confidence intervals and p-values not attributed to the sponsor are independently calculated from the posted summary statistics.
Continue through the Clinical Biostats statistical pathway
Use this trial's endpoint as a starting point for deeper study of effect measures, confidence intervals, and sample-size planning.
18. Record Summary
NCT02685202 is a terminated, single-group interventional study sponsored by the University of North Carolina, Chapel Hill. The registry records enrollment of 9 and describes a planned 16-week course of mandibular advancement splint therapy for adults with painful TMD and mild to moderate OSA. The primary endpoint was change in weekly mean pain index from baseline to 16 weeks.
The registry says pain-diary information could not be obtained, leaving primary outcome data unavailable. Numerical results for the listed secondary outcomes are not reported in the registry record. The adverse-event record lists 9 participants at risk, 0 serious adverse events, 0 other adverse events, and 0 deaths. The brief description refers to 12 intended participants, and the reason for the difference from registered enrollment is not reported in the registry record. The reason for termination and the statistical analysis plan are also not reported.