Study to Investigate the Stain Control of Two Stannous Fluoride Dentifrices: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for Study to Investigate the Stain Control of Two Stannous Fluoride Dentifrices (NCT03160703), a randomized na study. The primary outcome is Overall Modified Lobene Stain Index (MLSI) Mean Score at Week 4.

2. Clinical Question

3. Trial Design

This was a randomized, single-masked, parallel-group study with four dentifrice arms. The registry record lists enrollment of 220 participants and status as completed. The primary-outcome population is described separately as N=219; it required randomization, at least 1 dose of investigational product, and at least 1 post-baseline efficacy evaluation. The record does not explain the difference between the enrollment and analysis-population counts.

Two arms received experimental dentifrices containing 0.454% SnF2 and 5% STP, with abrasive silica listed at 2.0% or 3.5%. The reference arms received either a dentifrice containing 1000 ppm fluoride as SMFP or a dentifrice containing 0.454% SnF2. Arm descriptions also give approximate RDA values of 58, 77, 80, and 120, respectively. The main study question was whether stain build up differed across these products.

The outcome assessment was performed after 4 weeks of twice-daily use, with the primary measure described as an MLSI mean score at Week 4 and the timeframe listed as Baseline and Week 4. The registry record does not give further details about the randomization procedure, allocation concealment, or which participants were masked. It also does not report the protocol’s planned sample-size justification, the intended primary pairwise comparisons, or a prespecified statistical analysis plan. Those details should not be inferred from the randomized design or from the number of groups.

The registry lists one outcome measure and six analyses, but the primary outcome information includes several categories or time points and is not reduced to a single comparison in the available record. Consequently, the design identifies the groups and endpoint, but the registry information does not establish a single numerical contrast as the definitive answer to the study question.

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: A total of 225 participants were screened, of which 220 participants were enrolled and randomized in the study. A total of 5 participants were not randomized in study as 3 participants did not meet study criteria, and 2 withdrew their consent.

Overall Study

Reasons for not completing this period:

Analysis population for the primary outcome, as defined in the registry: The Intent-To-Treat (ITT) population (N=219) included all participants who were randomized, received at least 1 dose of investigational product, and had at least 1 post-baseline efficacy evaluation and were reported by randomized treatment.

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 Overall Modified Lobene Stain Index (MLSI) Mean Score at Week 4, measured over Baseline and Week 4.

The primary endpoint was the overall Modified Lobene Stain Index (MLSI) mean score at Week 4. The assessment concerned the area and intensity of dental stain on study teeth after 4 weeks of twice-daily dentifrice use. Stain intensity was scored separately in gingival and body areas, from 0 for no stain to 3 for heavy stain. Stain area was scored separately in those areas, from 0 for no stain to 3 for stain affecting more than two-thirds of the area.

Overall MLSI was calculated by multiplying the intensity and area scores. The resulting scale runs from 0, the best score, to 9, the worst score. A mean score offers a group-level summary of the measured stain burden, while the standard deviation describes how much individual scores vary around that mean. The endpoint is relevant to the stated question because it quantifies stain observed on the study teeth, rather than relying only on a general impression of product use.

The registry record states that baseline and Week 4 were the timeframe, but the listed primary outcome is a Week 4 mean score. It does not report the group means, standard deviations, baseline values, changes from baseline, or comparisons among arms. Thus the measurement method and scale are described, but the actual endpoint results and their precision are not reported in the registry record.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

The reported primary measure is a continuous score summarized as a mean with a standard deviation. In general, a mean describes the center of a group’s measurements, and a standard deviation describes their spread. Those summaries can help readers understand both the average stain score and the extent to which individual scores vary. Here, however, the registry record does not report the group means or standard deviations, so the summaries cannot be interpreted for any arm.

What does the MLSI score represent?

The MLSI combines two components: stain intensity and stain area. Intensity is graded from 0, no stain, to 3, heavy stain. Area is also graded from 0, no stain, to 3, stain affecting more than two-thirds of the area. The overall score is calculated by multiplying these component scores, giving the stated scale from 0 (best score) to 9 (worst score). A score is therefore not a direct percentage of tooth surface stained. It is a constructed index based on the two component ratings.

Because the index combines area and intensity, distinct patterns of staining could contribute to the same overall score. That is a general property of composite scores: the summary can be useful for comparing overall burden, but it does not preserve every detail of its components. The registry record does not report separate results for intensity and area, so those components cannot be considered independently.

What would a treatment comparison show?

For a continuous outcome, a comparison might report a difference in group means, together with a confidence interval. In general, a confidence interval describes the range of values reasonably compatible with the observed data and the statistical model. Its width reflects precision: a narrower interval indicates a more precise estimate under the analysis assumptions, while a wider interval indicates greater uncertainty. A confidence interval is not a guarantee that the true effect lies within its limits.

The four-arm design allows different possible comparisons, such as an experimental dentifrice against one of the reference dentifrices, or one experimental dentifrice against the other. Those contrasts answer different questions. The registry record lists six analyses but does not identify one numerical comparison as the sole primary contrast in the available outcome information. No contrast estimates or confidence intervals are reported. The product descriptions alone cannot be used to infer statistical differences.

Why does the analysis population matter?

The primary outcome population is described as ITT, with N=219, but the definition requires participants to have been randomized, received at least 1 dose, and had at least 1 post-baseline efficacy evaluation. Since it includes post-randomization requirements, readers should use the registry’s stated definition rather than assume that it includes every randomized participant regardless of follow-up. The record says participants were reported by randomized treatment, which indicates that treatment assignment was used for group attribution. The handling of participants without post-baseline evaluations and the handling of missing Week 4 measurements are not reported in the registry record.

In general, missing outcome data can affect interpretation if the availability of measurements is related to treatment assignment or to the outcome. Statistical approaches can make different assumptions about unobserved measurements, and those assumptions may affect estimates. The registry information does not specify an imputation method, a model for missing observations, or a sensitivity analysis. It is therefore not possible to assess how missingness was addressed or whether alternative assumptions were examined.

What can be inferred from the statistical plan?

The registry record does not report the planned statistical test, model, covariate adjustment, or method for controlling false-positive findings across multiple comparisons. It also does not report whether analyses were interim or whether any interim analysis was planned. These items should not be inferred from the fact that six analyses are listed. The record’s stated sample-size assumptions describe a planning illustration based on an observed effect, with two-sided significance level 0.05, equal allocation between two arms, and a normal approximation. They do not establish the trial’s own sample-size justification. The numerical planning outputs and the observed effect used for such an illustration are not reported in the information.

In general, over-dispersion matters when variation in the outcome exceeds what a statistical model assumes. If a model underestimates variation, standard errors may be too small and confidence intervals too narrow; if it accounts for excess variation appropriately, uncertainty estimates can better reflect the observed data. The registry record does not identify a model or report enough outcome information to assess whether over-dispersion was relevant to this continuous score.

Statistical significance, if it were reported, would not by itself describe the size or importance of an effect. Effect estimates and their uncertainty are needed for that assessment. Since the primary outcome estimates are not reported in the registry record, neither statistical significance nor precision can be evaluated. Any numerical sample-size planning illustration should be understood as a planning calculation, not as evidence about the probability that the trial detected an effect.

10. Multiplicity, Missing Data and Analysis Populations

The registry record lists one outcome measure and six analyses. The primary outcome information includes several categories or time points and is not reduced to a single comparison. The record does not identify which of the six analyses correspond to the primary question, how many comparisons were planned, or whether a multiplicity adjustment was used. When multiple hypotheses are tested, general statistical practice recognizes that the chance of at least one false-positive result can increase. Methods such as prespecified testing sequences or adjustment procedures can address that issue, but no such method is reported in the registry record. It is not possible to determine from the analysis count alone whether multiplicity affected interpretation.

The stated primary-outcome population is N=219. It includes randomized participants who received at least 1 dose and had at least 1 post-baseline efficacy evaluation, and results were reported according to randomized treatment. The record does not provide a participant flow explanation, arm-specific analysis counts for the primary outcome, or the reason for the difference between enrollment of 220 and the stated outcome population. Those details are relevant to understanding how many measurements contributed to each result.

The registry record does not report the approach to missing baseline or Week 4 measurements, any imputation procedure, or sensitivity analyses under alternative assumptions about missing outcomes. In general, these choices can affect estimates when data are incomplete. The posted information therefore does not permit an assessment of missing-data assumptions, the extent of missingness by group, or the robustness of results to missing measurements. Nor does it report the prespecified analysis population beyond the population definition.

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 1% reporting threshold.

Most frequent non-serious adverse event terms

The safety figures list 55 participants at risk for serious adverse events in each of the four dentifrice groups. Serious adverse events affected 0 participants in every group, and deaths were 0 in every group. The registry record lists 1 participant with other adverse events in Test Dentifrice 1 (RDA~58) and 1 in Reference Dentifrice 1 (RDA~80); the corresponding counts are 0 in Test Dentifrice 2 (RDA~77) and Reference Dentifrice 2 (RDA~120).

These figures are counts over the groups and event categories stated in the registry. They should not be read as a comparison of rates unless the relevant exposure period, event definitions, and analysis are considered. The record does not provide further detail about event types, timing, severity, relationship to dentifrice, or whether participants experienced more than one event. No serious-event terms are listed. A count of 0 observed serious events does not establish that an event is impossible or that the groups are equivalent in safety; it describes what was recorded among the participants at risk in this study.

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

The record supports a description of the study’s purpose, design, intervention groups, and primary measurement. It was a randomized, single-masked, parallel-group comparison of two experimental SnF2/STP dentifrices and two reference dentifrices. The primary endpoint was the overall MLSI mean score after 4 weeks of twice-daily use, with a scale from 0 (best score) to 9 (worst score). These registry entries explain what the study set out to measure.

The record does not report the primary outcome means, standard deviations, treatment contrasts, confidence intervals, or p-values. Therefore, it does not establish which group had a higher or lower score, the size of any difference, or the precision of an estimated effect. This is a limit on what can be concluded from the registry information, not evidence that there was no difference. The individual score scale and the names of the products do not substitute for observed outcome results.

The safety counts describe no serious adverse events and no deaths among the groups as recorded, alongside the stated counts of other adverse events. These counts are not sufficient to establish equivalence or rule out uncommon events. The registry information does not detail event type, follow-up duration for safety, or relationship to product use.

More broadly, a trial’s stated objective is distinct from its result. A comparison can be evaluated only when numerical results and their uncertainty are available and the analysis is understood. The record’s description of the ITT population and the existence of six analyses do not supply those missing estimates. The information also does not state the statistical plan, missing-data methods, multiplicity approach, or sample-size justification. Conclusions about comparative stain outcomes, statistical significance, or practical importance would go beyond what is reported in the registry record.

13. Why This Trial Matters Statistically

This study illustrates why a well-defined endpoint and reported numerical results are both essential to statistical interpretation. The MLSI is described in detail: it combines ratings of stain intensity and area, and its direction is explicit, with 0 the best score and 9 the worst. That makes the intended measurement understandable. But knowing the measurement scale does not reveal the observed group values or the uncertainty around comparisons.

The four-arm design also makes the choice of contrast important. A comparison between an experimental dentifrice and a reference dentifrice addresses a different question from a comparison between the two experimental formulations. The registry record lists six analyses but does not identify a single reported contrast that can be interpreted as the primary result. This is a useful reminder that the number of analyses is not a substitute for transparent reporting of which comparisons were planned and how they were analyzed.

The stated analysis population is another statistical consideration. Its definition includes receipt of at least 1 dose and at least 1 post-baseline evaluation, while the enrollment count is 220 and the outcome population is N=219. Without participant flow and missing-data details, readers cannot fully assess how inclusion in the analysis relates to randomization or how complete the endpoint data were.

Finally, the registry record separates design information from evidence about an outcome. Randomization and a defined score establish a framework for comparison, but they do not disclose the comparison’s magnitude or precision. This trial is statistically informative as an example of why registry reporting should make outcome estimates, analysis choices, and uncertainty available alongside the study design.

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.

The most important limitation of the registry information for interpreting this trial is that the primary outcome values are not reported. The record describes a Week 4 MLSI mean score and its standard deviation as the outcome format, but gives no group means, standard deviations, or treatment contrasts. There is consequently no basis for assessing direction, magnitude, or precision of the stain-score results.

The outcome description refers to baseline and Week 4, while the primary outcome title specifies the Week 4 score. The available information does not explain whether the primary analysis used a Week 4 value, a change from baseline, or another model that accounted for baseline. It also does not report separate component scores for stain area and intensity.

The analysis-population definition and counts leave unanswered questions about participant flow. Enrollment is 220 and the stated outcome population is N=219, but the record does not explain the difference or provide arm-specific primary-outcome counts. The definition requires a post-baseline efficacy evaluation, while missing-data methods and sensitivity analyses are not reported.

The record lists six analyses without describing their hypotheses, statistical methods, or multiplicity control. It does not state the sample-size justification, the planned comparison structure, or whether any interim analyses occurred. The listed sample-size assumptions are for a planning illustration and do not document the trial’s own design rationale. For safety, the counts do not include details on event types, timing, severity beyond the serious versus other categories, or relationship to treatment. Each limitation restricts conclusions to the study description and the event counts that are actually reported.

15. Related Tutorials

16. Related Statistical Calculators

17. Sources

• ClinicalTrials.gov: Study to Investigate the Stain Control of Two Stannous Fluoride Dentifrices — NCT03160703.
• Registry record last updated 2019-06-04; status last verified 2019-05.
• Results first posted 2019-01-17.
• 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

NCT03160703 is a completed randomized, single-masked, parallel-group study with enrollment of 220. It compared two experimental dentifrices containing 0.454% SnF2 and 5% STP, with different listed abrasive silica levels, against a marketed SMFP reference dentifrice and a marketed SnF2 reference dentifrice.

The primary outcome was the overall MLSI mean score at Week 4 after 4 weeks of twice-daily use. The registry describes the score as ranging from 0 (best) to 9 (worst). The stated outcome population was N=219, defined by randomization, receipt of at least 1 dose, and at least 1 post-baseline efficacy evaluation.

Group-level primary outcome values and numerical comparisons are not reported in the registry record. Safety figures list 0 serious adverse events and 0 deaths in each group, with 1 other adverse event each in Test Dentifrice 1 and Reference Dentifrice 1, and 0 in the other groups. The record does not report the statistical analysis details needed to assess the primary comparisons.