Gingival Crevicular Fluid Characterization During Orthodontic Treatment: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for Gingival Crevicular Fluid Characterization During Orthodontic Treatment (NCT04226469), a registered phase not stated study. The primary outcome is The Distance of Tooth Movement.

2. Clinical Question

The study also concerns the characterization of gingival crevicular fluid during orthodontic tooth movement. Its background describes the biological processes involved in tooth movement and notes uncertainty about changes in gingival crevicular fluid. However, the registry record does not provide results for fluid measurements or identify the other outcome measures in enough detail to interpret them.

3. Trial Design

The study is registered as NCT04226469, titled “Gingival Crevicular Fluid Characterization During Orthodontic Treatment.” The official title describes characterization of gingival crevicular fluid during orthodontic tooth movement. The sponsor is the University of Illinois Chicago. The registry lists an enrollment of 15 participants and a tooth-movement procedure.

The group description concerns subjects who require canine retraction. Gingival crevicular fluid is collected during tooth movement, with the initial timepoint serving as the control. This is not described as a comparison between separate randomized groups: the registry record says allocation is not stated and flags the arms as not a like-for-like control comparison. The initial timepoint should therefore be understood as a timepoint reference, not as evidence of a separate untreated group.

The primary outcome is the distance of distal canine movement, reported as a mean with standard deviation and measured in millimeters. The stated timeframe is 7 weeks, and the description defines the measure as distance from the initial timepoint to the end of study. The record lists three outcome measures in total, but does not give results or analysis details for them.

The study began on 2019-01-01, reached primary completion on 2021-05-05, and has COMPLETED status. The registry record does not report the analysis plan, participant flow, further visit schedule, or a sample-size justification. These details cannot be inferred from the listed enrollment or study dates.

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

Analysis population for the primary outcome, as defined in the registry: the distance of canine movement distally

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.

6. Primary Endpoint

The registry lists the primary outcome as The Distance of Tooth Movement, measured over 7 weeks.

The primary endpoint is the distance of canine movement distally, measured in millimeters from the initial timepoint to the end of study. Its stated timeframe is 7 weeks. The registry specifies that the outcome is expressed as a mean and standard deviation.

Distance is a direct measure of the tooth movement under study: it quantifies how far the canine moved over the stated interval. The mean describes the average distance across the analyzed observations, while the standard deviation describes how spread out individual distances are around that average. These summaries address different aspects of the data; the mean alone would not show how variable the movements were.

The registry record identifies this outcome as primary but does not report its observed mean, standard deviation, number of participants contributing data, or an uncertainty interval. It also does not explain how distance was measured or how measurements were handled if a participant had incomplete follow-up. Consequently, the endpoint's definition can be described, but its observed magnitude and precision cannot be assessed from the registry record.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

The registry identifies a continuous primary outcome: distance of distal canine movement, measured in millimeters and summarized as a mean with standard deviation. For a continuous outcome, the mean gives a central summary of the measured distances. The standard deviation describes their spread around that mean. A mean and standard deviation do not, on their own, show the uncertainty in the mean or the distribution of individual measurements.

What does a confidence interval describe?

In general, a confidence interval gives a range of values that are reasonably compatible with the data and the method used to calculate the interval. Its width reflects precision: wider intervals indicate less precise estimation, while narrower intervals indicate greater precision under the same assumptions. The registry record does not report a confidence interval for the primary outcome, so its precision cannot be assessed from the posted results.

What would a hypothesis test add?

In general, a hypothesis test evaluates whether the observed data are inconsistent with a specified null hypothesis under a statistical model. A p-value is not the probability that the null hypothesis is true, nor does it measure the size or importance of an effect. The registry record lists zero analyses and does not report a p-value or describe a testing plan. Statistical significance therefore cannot be evaluated from this record. Even if a test result were available, it would need to be read alongside the estimated distance and its uncertainty.

How should the timepoint reference be understood?

The registry describes the initial timepoint as the control and says the group consists of subjects requiring canine retraction. This supports understanding the reference as the initial measurement in the treatment context, not as a separate randomized group. In general, repeated measurements on the same participant can be statistically related; an analysis should account for that dependence when comparing timepoints. The registry record does not describe the analysis method or say whether the primary outcome was analyzed as paired measurements.

Allocation is not stated, and the record flags the arms as not a like-for-like control comparison. Accordingly, a between-group treatment-effect interpretation should not be assumed. The record also does not describe adjustment for other variables, handling of repeated measurements, model choice, or assumptions checked for the primary outcome.

What do the planning assumptions mean?

The stated planning illustration uses a two-sided significance level of 0.05, equal allocation between two arms, and a normal approximation. The target effect is defined as a stated fraction of the observed effect. In general, a planning calculation estimates the sample size needed to detect a specified effect under its assumptions. It is not a measure of what the completed study actually detected. The planning figures are illustrations, not observed power, and do not establish that the study had adequate power for its primary outcome.

The record does not report a study-specific sample-size justification or the numerical inputs and results needed to assess one. In particular, the primary outcome result is not reported, so the observed effect underlying any illustration cannot be evaluated from the registry record. The assumed equal allocation between two arms also should not be mistaken for evidence that the enrolled participants were randomized or assigned to separate groups.

In general, over-dispersion matters when data vary more than a statistical model expects, because standard errors and uncertainty estimates can then be misleading if the model does not account for the extra variation. That issue is not identified as an analysis feature in this record. The endpoint is continuous, and no model, residual diagnostics, or dispersion assessment is reported. It would be inappropriate to infer that over-dispersion was present or that a particular adjustment was used.

Overall, the methods information supports describing the outcome type and stated planning assumptions, but not reconstructing an analysis. The registry record does not report the calculations used for the primary endpoint, the estimated effect, its uncertainty, or the assumptions actually checked.

10. Confidence Intervals for Each Arm

No two-arm comparison is shown for this trial, but each arm's mean can be given with a t-based 95% confidence interval computed from the posted mean, spread and number of participants.

R code and output

arm <- c("Subjects Require Canine Retraction")
n   <- c(15)
m   <- c(5)
sp  <- c(0.5)
sd  <- sp      # posted standard deviations
for (i in seq_along(n)) {
  se <- sd[i] / sqrt(n[i]); h <- qt(0.975, n[i] - 1) * se
  cat(sprintf("CARM|%s|%d|%.3f|%.3f|%.3f|%.3f\n", arm[i], n[i], m[i], sd[i], m[i] - h, m[i] + h))
}

CARM  Subjects Require Canine Retraction  15  5.000  0.500  4.723  5.277

11. Multiplicity, Missing Data and Analysis Populations

The registry lists three outcome measures and zero analyses. It identifies distance of tooth movement as the primary outcome, but does not report the names, definitions, or results of the other outcome measures in the record summarized by these registry entries. A multiplicity plan—such as which outcomes were confirmatory or how multiple statistical tests were handled—is not reported in the registry record.

Multiplicity can arise when several outcomes, timepoints, or statistical tests are evaluated. In general, testing many questions without an appropriate plan can increase the chance of at least one apparently notable result arising by chance. The record does not say whether multiple testing was relevant to the study's analyses or whether any adjustment was planned. Since no analyses or outcome results are listed, the impact of multiplicity cannot be assessed.

Missing-data methods and the number of participants with observed primary-outcome data are not reported in the registry record. The enrollment is 15, but the record does not state whether all participants completed the study, whether all had a measurement at the end of study, or whether any data were excluded. It also does not describe imputation, complete-case analysis, or sensitivity analyses. These omissions prevent assessment of how incomplete observations might affect an estimate.

The analysis population is not reported in the registry record. The record does not specify whether analyses included all enrolled participants, only those with complete measurements, or another defined set. These distinctions matter because the analyzed participants may not represent everyone enrolled. Without participant flow and population definitions, the denominator behind any estimate cannot be checked—and no primary estimate is posted to clarify it.

12. Safety Results

The registry reports serious adverse events as affected participants divided by participants at risk.

Deaths

Other (non-serious) adverse events

Participants with at least one non-serious event at or above the registry's 0% reporting threshold.

The registry lists 15 participants at risk for serious adverse events and 0 with serious adverse events. It also lists 15 at risk for other adverse events and 0 with other adverse events, with 0 deaths. These figures describe the safety counts recorded for the group of subjects requiring canine retraction.

A count of zero recorded events is not proof that an event could never occur, nor does it establish comparative safety. The registry describes no separate like-for-like control group, and the allocation method is not stated. Without a comparable group and information about how safety events were collected, these counts cannot estimate a difference attributable to treatment.

The registry record does not report event definitions, observation duration for adverse events, severity or relatedness assessments, or whether any participants were lost to safety follow-up. The primary endpoint timeframe is 7 weeks, but the record does not specify whether that is also the safety observation period. The listed counts should therefore be read as the recorded event totals, with these limitations in mind.

13. What the Result Does, and Does Not, Mean

The record describes a study of canine retraction during orthodontic tooth movement and identifies distal tooth-movement distance over 7 weeks as its primary outcome. It reports enrollment of 15 participants and identifies the initial timepoint as the control. These registry entries describe the study question and context, not the outcome result.

The registry record does not report the observed mean distance, its standard deviation, a confidence interval, or a statistical test. It is therefore not possible to tell from the record how much movement was observed, how variable it was, or how precisely it was estimated. The absence of a posted result should not be interpreted as evidence of no movement or of a particular direction or magnitude.

The initial timepoint is not described as an independent control group, and allocation is not stated. Any timepoint comparison would have to be interpreted in that design context. Without a randomized, like-for-like comparison, a change over time would not alone distinguish effects of the procedure from other influences occurring during the study.

The registry's background discusses biological processes and uncertainty about gingival crevicular fluid during orthodontic treatment. That background supplies a rationale for studying the topic, but it is not evidence of a result. The record does not provide the fluid-measurement results needed to assess biomarker changes. Likewise, zero recorded adverse events in the listed categories is a descriptive safety count, not proof of absence of risk or evidence of comparative safety.

In general, a study result is most informative when the estimate, its precision, analysis population, and design limitations are considered together. Here, the endpoint and some design details are available, but the outcome estimates and analysis details are not reported in the registry record. Interpretation must remain limited to that distinction.

14. Why This Trial Matters Statistically

This study is statistically notable because it distinguishes a timepoint reference from a separate comparison group. The registry identifies the initial timepoint as the control and explicitly says the arms are not a like-for-like control comparison. That distinction is central to interpretation: a baseline reference and a randomized comparator answer different questions and support different causal claims.

The primary outcome is a continuous measure of tooth movement, expressed as a mean and standard deviation. For such outcomes, the estimated magnitude and its uncertainty are both important. Reporting only an average would not show the spread of observations, and reporting only a test result would not communicate the size or precision of movement. The registry record gives the measurement definition but not these numerical results.

The record also illustrates why enrollment alone does not establish the amount of information available for analysis. Although 15 participants are listed, the number contributing measurements, completeness of follow-up, and analysis population are not reported. Those details are needed to understand the denominator and the potential influence of missing observations.

Planning calculations can help explain the sample size that might be needed under specified assumptions, but they are not a substitute for results from the completed study. The record's stated planning approach uses a two-sided significance level of 0.05, equal allocation, and a normal approximation. Its planning illustrations are not observed power, and the record does not provide the outcome estimates needed to judge the observed effect.

Finally, the biological rationale and the clinical measurement are related but not interchangeable. Gingival crevicular fluid is part of the study's stated context, while the identified primary endpoint is distance of tooth movement. Since the record does not report the biomarker results or statistical analyses, neither biological changes nor their relationship to movement can be evaluated from the registry record.

15. 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.

The most immediate limitation for interpretation is that the registry record names the primary endpoint but provides no outcome estimate. The mean distance, standard deviation, uncertainty interval, and analysis result are not reported in the registry record. The number of participants contributing endpoint data is also not stated, so the enrollment of 15 cannot be treated as the analyzed sample size.

The design information limits causal interpretation. The initial timepoint is the control, the allocation method is not stated, and the record flags the arms as not a like-for-like control comparison. A separate randomized comparator is not described. The record does not explain how measurements across timepoints were modeled or whether within-participant dependence was accounted for.

Participant characteristics and eligibility details are not reported in the registry record. The listed conditions include healthy status, maxillary first premolar tooth extraction, and canine retraction, but the record does not provide enough information to characterize the participants beyond the group description. The measurement procedure, assessor methods, and handling of incomplete observations are also not described.

Although three outcome measures are listed, their full definitions and results are not reported, and the record lists zero analyses. A plan for multiplicity, missing data, and analysis populations is not reported in the registry record. Safety counts are given, but adverse-event definitions and the safety observation period are not specified. These limitations prevent a fuller assessment of precision, bias, and generalizability.

16. Related Tutorials

17. Related Statistical Calculators

18. Sources

• ClinicalTrials.gov: Gingival Crevicular Fluid Characterization During Orthodontic Treatment — NCT04226469.
• Registry record last updated 2025-05-07; status last verified 2025-05.
• Results first posted 2025-05-07.
• 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.

19. Record Summary

NCT04226469 is a completed study sponsored by the University of Illinois Chicago, with enrollment of 15. The study concerns gingival crevicular fluid characterization during orthodontic tooth movement in subjects requiring canine retraction. The initial timepoint is identified as the control; allocation is not stated, and the record does not describe a randomized, like-for-like comparison.

The primary outcome is distal canine movement distance in millimeters, summarized as a mean and standard deviation over 7 weeks. The record lists three outcome measures and zero analyses but does not report the primary outcome result or its uncertainty. Safety counts list 0 serious adverse events, 0 other adverse events, and 0 deaths among 15 at risk in each category. Missing-data methods, analysis populations, and a multiplicity plan are not reported in the registry record.