Evaluation of the Efficacy and Safety of a Loop Stretchable Dental Floss: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for Evaluation of the Efficacy and Safety of a Loop Stretchable Dental Floss (NCT06515483), a randomized na study. The primary outcome is Dental Plaque Assessment.

2. Clinical Question

3. Trial Design

The registry describes a randomized, single-blind, parallel-group clinical trial at a single center. Participants were assigned to brushing and flossing or to brushing only. Random allocation is intended to balance, across groups, factors that could influence the outcome, including factors that were not measured. It does not guarantee that the groups will be identical, especially in a trial of this size; the actual allocation method and any procedures used to conceal assignments are not reported in the registry record.

The record lists enrollment of 64 and marks the study as completed. Its recorded start date is 2024-10-15, and primary completion is recorded as 2024-12-04. The trial title and description identify an evaluation over 30 days, with dental plaque examined at baseline and at the 30-day examination. The primary outcome is continuous: individual plaque scores are averaged across examined tooth surfaces. The record identifies the mean and standard deviation as the outcome summary measures.

The registry describes the trial as single-blind, but which people were masked is not reported in the registry record. This matters because knowledge of assignment could influence participant behavior, outcome assessment, or both. The record does not specify the assessor’s role or masking procedures. The sponsor is Indiana University. The phase is listed as NA.

The two arms are described as “Brushing and Flossing” and “Brushing only.” The brief description identifies Floss Loops as the stretchable floss used in the experimental group. The record does not provide enough detail to assess how the intervention was standardized, how adherence was measured, or whether participants received other study-specific instructions. Those details would help readers understand what the assigned intervention involved in practice, but should not be inferred from the arm labels.

One patient who did not complete the 30-day follow-up examination was excluded from the efficacy analysis. The record does not identify a named analysis population or provide a fuller account of participant flow. Thus, the design can be described as randomized and parallel, but the exact analysis procedures and the extent to which all randomized participants contributed to each outcome 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.

Before assignment: There were not significant events reported prior to participants enrollment.

Overall Study

Reasons for not completing this period:

Analysis population for the primary outcome, as defined in the registry: One patient who did not complete the 30-day follow-up examination was not included in the efficacy analysis.

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.

Population: Both groups had 32 participants at the beginning of the study.

6. Primary Endpoint

The registry lists the primary outcome as Dental Plaque Assessment, measured over Baseline and 30 days examination.

The primary endpoint is dental plaque measured with the Turesky modification of the Quigley-Hein Plaque Index. Plaque is identified with a disclosing solution, then scored on a scale from 0 to 5. A score of 0 means no plaque was detected; a score of 5 indicates plaque covering 2/3 or more of the tooth’s crown. Intermediate scores reflect the amount of plaque covering the tooth. Higher scores represent more accumulated plaque and a worse surface-level outcome.

Each tooth other than a third molar is assessed at six sites: mesio-buccal, buccal, disto-buccal, mesio-lingual, lingual, and disto-lingual. For each individual, the index is calculated by adding the surface scores and dividing by the number of surfaces examined. The resulting measure summarizes plaque across the assessed surfaces rather than describing a single tooth or site.

Using a defined index allows plaque to be recorded in a consistent, quantitative way and makes it possible to compare group averages. A mean describes the average score, while a standard deviation describes how dispersed individual scores are around that average. The registry specifies baseline and 30-day examinations. However, the numerical endpoint results and a selected comparison between groups are not reported in the registry record, so the size and precision of any change or difference cannot be described.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

The primary measure is continuous: it is an average plaque index score, with the registry specifying means and standard deviations. The record does not state which inferential statistical test or model was used. A method such as a two-group comparison of means might be used in some settings, but it cannot be attributed to this trial without a documented analysis description. The choice of method depends on the design, the observed data, and the assumptions used by the investigators.

What do the mean and standard deviation describe?

A mean is the arithmetic average of a set of observations. In this trial, the individual index is formed by adding scores across examined tooth surfaces and dividing by the number of surfaces examined. A group mean can then summarize the average index for participants in that group at a particular assessment. The standard deviation describes how spread out individual observations are around their mean. It is not the same as the uncertainty in the estimated group mean: that uncertainty also depends on the number of observations and the analysis method.

For a bounded index, the mean offers a compact summary, but it does not show the full distribution of scores. Participants can have different patterns of plaque across surfaces even when their overall averages are similar. A mean and standard deviation alone may not reveal skew, clustering, or unusual observations. The registry record does not provide the numerical distributions, so it is not possible to assess those features for this trial. General statistical interpretation should distinguish the summary measure from the underlying pattern of participant-level data.

Why does the comparison need a clear time point?

The registry identifies baseline and 30-day examinations, but also notes that the primary outcome has several categories or time points and was not reduced to one comparison. In a study with repeated measurements, a result can be expressed as an endpoint value, a change from baseline, or a comparison of changes between groups. These are different estimands: each answers a different question and can produce different estimates. The record does not identify one selected contrast or explain whether baseline scores were incorporated into an adjusted analysis. The result should therefore not be reconstructed by choosing a comparison on the reader’s behalf.

How should precision be considered?

A confidence interval is a statistical range used to express uncertainty around an estimated effect under a particular model and sampling process. A narrow interval generally indicates greater precision than a wide interval, while the interval’s position relative to a null value is often used when interpreting evidence for a difference. A confidence interval does not describe the range of individual outcomes, and it does not guarantee that the true effect lies within the reported limits. No confidence interval for a primary between-group comparison is reported in the registry record, so precision cannot be evaluated numerically.

Statistical significance and clinical importance are also distinct. A test result, if available, would address compatibility with a null hypothesis under specified assumptions. It would not by itself show whether a difference is large enough to matter in practice. Assessing practical importance requires the effect estimate, its uncertainty, the outcome’s scale, and a context for judging meaningful differences. The registry does not report a primary effect estimate or a threshold for a meaningful change, so neither statistical nor clinical importance can be judged from the listed information.

What does randomization contribute?

Random allocation is intended to reduce systematic differences between treatment groups at the point of assignment. Its benefit is strongest when the assigned groups are analyzed in a way that preserves the randomized comparison. The actual allocation sequence, concealment procedure, and named analysis populations are not reported in the registry record. The record also notes an efficacy exclusion for one participant who did not complete follow-up. Without a fuller account of participant flow and analysis procedures, readers cannot determine how closely the efficacy analysis follows assignment or how missing data were addressed.

Blinding can reduce some forms of bias, but “single-blind” alone does not identify who was masked. In a behavioral intervention involving flossing, participants may know whether they are flossing; the registry does not state which participants or study personnel were blinded or how outcome assessment was conducted. The plaque index uses a disclosing solution and scored tooth surfaces, but the description does not establish whether assessors were unaware of group assignment. These details are not reported in the registry record and should not be assumed.

What can planning calculations say?

A sample-size planning calculation is a design aid, not a measure of the evidence actually observed. The record describes planning illustrations based on a fraction of the observed effect, equal allocation, a two-sided significance level of 0.05, and a normal approximation. Such illustrations describe hypothetical participants per arm for a specified planning target; they are not observed power and do not replace the trial’s outcome estimates or their uncertainty. The trial’s own sample-size justification is not reported in the registry record. Since a single primary effect estimate is not reported, planning figures should not be interpreted as evidence that the study detected, or was capable of detecting, a particular clinically meaningful difference.

10. Multiplicity, Missing Data and Analysis Populations

The registry lists three outcome measures and nine analyses, and notes that the primary outcome has several categories or time points rather than one selected comparison. These features raise questions about multiplicity: when several outcomes, time points, or contrasts are examined, the chance of obtaining an apparently notable result by chance can increase if each is tested independently. Statistical approaches can address this in different ways, but the appropriate approach depends on which comparisons were planned and which were exploratory.

The registry record does not report whether a multiplicity adjustment was used, which analysis was designated as primary among the listed categories or time points, or how the analyses were organized. It is therefore not possible to identify a prespecified hierarchy or to determine how any test results should be interpreted across the analyses. No significance claims should be constructed from the count of analyses alone.

For missing data, the record specifically states that one patient did not complete the 30-day follow-up examination and was not included in the efficacy analysis. It does not report the reason for non-completion, the participant’s assigned group, or any method for handling missing observations. The record also does not describe imputation, sensitivity analyses, or whether all randomized participants were included in analyses other than efficacy.

The named analysis populations, including whether the efficacy analysis followed intention-to-treat or another principle, are not reported in the registry record. The stated exclusion is important for understanding the reported population, but it is not enough to establish the full analysis strategy. These missing details limit assessment of the risk that the analyzed data differ systematically from the randomized groups.

11. 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 reports safety counts separately for the two trial arms. For Arm 1, 31 participants were listed as at risk for serious adverse events and 31 as at risk for other adverse events; the corresponding affected counts were 0 and 0, and deaths were 0. For Arm 2, 32 participants were listed as at risk for serious adverse events and 32 as at risk for other adverse events; the affected counts were 0 and 0, and deaths were 0. No serious adverse event terms are listed.

These figures describe the events recorded in the registry for the listed groups. They do not show that no event of any kind occurred outside the registry’s definitions or reporting procedures, and they do not establish comparative safety. The registry record does not give event descriptions for other adverse events, a detailed collection method, or an account of the duration and completeness of safety monitoring. The counts should therefore be read as reported safety outcomes, not as proof that either intervention is free of risk.

The numbers at risk are the relevant denominators for reading the listed counts. The registry presents no serious adverse events, other adverse events, or deaths in either group in these entries. With no event counts reported, a comparative risk estimate or its precision cannot be assessed from this information. Safety interpretation should remain specific to these recorded categories and the follow-up captured by the trial.

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

The registry record establishes that a randomized, single-blind, parallel-group trial was completed to compare brushing plus Floss Loops with brushing alone. It identifies dental plaque as the primary outcome, describes how the index is scored, and specifies baseline and 30-day examinations. It also reports a secondary outcome, Bleeding on Marginal Probing, and lists safety counts for both arms. These details clarify what the study was designed to examine.

They do not establish the size or direction of an efficacy result. The registry does not report a single numerical primary comparison, group means, an effect estimate, a confidence interval, or a test result for the primary outcome in the available record. The note that the outcome has several categories or time points and was not reduced to one comparison further limits any attempt to summarize a main effect. The study title and stated purpose describe an evaluation, not a finding.

The recorded safety entries show no affected participants in the listed serious or other adverse-event categories and no deaths in either arm. That is a description of the reported counts, not evidence that all possible harms were ruled out. The safety entries alone also cannot establish whether one assigned approach is safer than another.

Enrollment of 64 and the report that one patient did not complete the 30-day examination provide context for the study’s scale and efficacy analysis. They do not reveal the precision of an outcome estimate, particularly when no such estimate is reported. A planning calculation based on an observed effect would remain a hypothetical design illustration, not observed power and not a substitute for the actual trial result.

Accordingly, the registry record supports a careful account of the trial question, design, endpoint definition, and recorded safety counts. It does not support a conclusion about whether adding flossing changed plaque scores or bleeding outcomes. Interpreting efficacy would require the numerical outcome results, the selected comparisons, and the statistical analysis details, none of which are reported in the registry record as a single primary comparison.

13. Why This Trial Matters Statistically

This trial illustrates why a clearly defined endpoint and a clearly reported comparison are both necessary for statistical interpretation. The registry gives a detailed description of the plaque index, including the surface-level scoring and the way an individual average is formed. That makes the measurement more understandable. But an endpoint definition cannot replace the group results: without numerical estimates and their uncertainty, readers cannot judge how much the groups differed or how precisely the difference was estimated.

The design also highlights the importance of distinguishing the question a trial was intended to answer from the result available for interpretation. Randomization and a parallel-group comparison set up a framework for comparing brushing plus flossing with brushing alone. The record’s note that the primary outcome has several categories or time points, without one selected comparison, shows why the analysis target matters. A baseline-to-follow-up contrast, an endpoint comparison, and a comparison of changes are not interchangeable descriptions of an effect.

Missing follow-up and analysis populations are also statistical concerns, not merely administrative details. The record identifies one participant who did not complete the 30-day examination and was excluded from efficacy analysis, but does not explain the wider analysis strategy. Readers need this context to understand which participants contribute to an estimate and how the randomized comparison is preserved.

Finally, the safety counts demonstrate the difference between reporting no events in listed categories and establishing the absence of risk. The counts are informative as registry entries, but interpretation also depends on event definitions, monitoring, and the precision of comparisons. This trial is therefore useful as an example of how endpoint definition, analysis selection, missingness, and complete result reporting jointly determine what can be learned from a clinical study.

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 specific to this trial constrain interpretation of the registry record. Most importantly, it does not report one numerical primary-outcome comparison despite identifying dental plaque as the primary outcome and specifying baseline and 30-day assessments. Group-level scores, effect estimates, confidence intervals, and test results for a selected comparison are not reported in the registry record. As a result, neither the magnitude nor the precision of a plaque difference can be evaluated.

The registry notes that the primary outcome has several categories or time points and was not reduced to one comparison. It does not identify which contrast was primary, how the multiple analyses were handled, or whether any multiplicity adjustment was used. The number of analyses and outcome measures is recorded, but those counts do not reveal which results were prespecified or how the analyses relate to each other.

One patient did not complete the 30-day examination and was excluded from the efficacy analysis. The record does not give the reason for non-completion, identify the assigned group, or describe methods for handling missing values. It also does not specify the named analysis populations. These omissions prevent assessment of whether the efficacy analysis maintained the randomized comparison or how sensitive it might be to the missing follow-up.

The study is described as single-center and enrolled 64 participants. The registry record does not provide further information about eligibility characteristics or participant demographics, which limits assessment of how closely the study population represents other settings. It says the trial was single-blind but does not specify who was masked or how outcome assessors were protected from knowledge of assignment. Intervention adherence and protocol details are also not reported in the registry record.

These limitations concern what can be interpreted from the record; they do not establish that the trial procedures were inadequate. They identify information needed to assess the result and its applicability, which is not reported in the registry record.

15. Related Tutorials

16. Related Statistical Calculators

17. Sources

• ClinicalTrials.gov: Evaluation of the Efficacy and Safety of a Loop Stretchable Dental Floss — NCT06515483.
• Registry record last updated 2025-06-13; status last verified 2025-02.
• Results first posted 2025-06-13.
• 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.

18. Record Summary

NCT06515483 is a completed, randomized, single-blind, parallel-group, single-center clinical trial sponsored by Indiana University. It enrolled 64 participants and compared brushing plus Floss Loops stretchable floss with brushing only. The recorded start date is 2024-10-15, and primary completion is recorded as 2024-12-04. The phase is listed as NA.

The primary outcome was dental plaque measured with the Turesky modification of the Quigley-Hein Plaque Index at baseline and the 30-day examination. Bleeding on Marginal Probing was listed as a secondary outcome. The record notes that one patient did not complete follow-up and was excluded from efficacy analysis. It reports no serious adverse events, other adverse events, or deaths in either arm in the listed safety entries. A single numerical primary-outcome comparison, its precision, and detailed analysis procedures are not reported in the registry record.