Effects of an Oxalate Containing Product on Dentinal Hypersensitivity With Dental Prophylaxis: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for Effects of an Oxalate Containing Product on Dentinal Hypersensitivity With Dental Prophylaxis (NCT02481557), a randomized na study. The primary outcome is Change From Baseline Air Challenge.

2. Clinical Question

3. Trial Design

The registry describes a randomized, parallel-group trial with no masking. The listed allocation was randomized, and the intervention was a professionally applied oxalate salt solution compared with no treatment. The study summary frames the assessment around dental prophylaxis, with sensitivity assessed in the presence or absence of the potassium oxalate salt solution. No placebo or sham procedure is listed.

The registry lists an enrollment of 36. It also states that Thirty-Six (36) subjects received products and Thirty-Six (36) subjects completed the study. For the primary outcome, the reported group sizes are 17 for oxalate salt solution and 19 for no treatment. These are the group counts associated with the posted primary outcome results; the record does not explain how participant flow led to those analysis counts or whether any subjects were excluded from a particular analysis.

The primary outcome was change from baseline in air-challenge response, measured using the Schiff Sensitivity Scale at 10 Minutes. A secondary outcome was change from baseline for the Yeaple Probe, also assessed at 10 Minutes. The registry reports the trial as completed. The start and primary completion dates are both recorded as 2015-06.

The registry does not report the trial's original sample-size justification, detailed eligibility criteria, allocation concealment procedures, or a fuller account of how outcomes were collected. It also does not report the prespecified statistical analysis plan, interim analyses, or a detailed definition of the analysis population. Those omissions limit assessment of how closely the posted outcome results can be compared with the trial's original intended analyses.

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: Thirty-Six (36) subjects received products. Thirty-Six (36) subjects completed the study.

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 Change From Baseline Air Challenge, measured over 10 Minutes.

The primary endpoint was change from baseline in response to an evaporative air challenge, measured using the Schiff Sensitivity Scale at 10 Minutes. The examiner recorded a Schiff Index score for each test tooth in response to the challenge. The scale ranges in meaning from no response, through a response without a request to stop the stimulus, to a response that prompts a request to stop; its highest described score corresponds to a response considered painful with a request to discontinue the stimulus.

The registry states that a negative change from baseline represents a decrease in sensitivity. This direction note is important when reading the group means: negative values represent a lower score after the intervention relative to baseline, while the between-group estimate compares the reported changes. The primary outcome is presented as a mean with standard deviation, treating the recorded scale change as a continuous measure for summarizing group results.

An air challenge provides a standardized stimulus for eliciting and recording a sensitivity response. Using a scored response makes it possible to summarize changes across subjects, though a group mean does not show the full distribution of individual responses or how many subjects had a particular score. The registry does not report further information about the number of teeth contributing to each participant's outcome or how tooth-level observations were combined, beyond stating that the mean change from baseline was calculated for this measure.

7. Results Posted in the Registry

• No Treatment: mean -0.13 versus -0.41 on control; difference 0.28 (95% CI -0.03 to 0.59), standardized effect d = 0.59; z-test p = 0.080.

8. Secondary Efficacy Endpoints

The registry also posts results for secondary outcomes. For each outcome below, the endpoint type, the test applied to the posted summary statistics, the result and its interpretation are given in turn. Secondary endpoints are usually not adjusted for multiple testing, so they support rather than confirm the primary finding.

Change From Baseline for Yeaple Probe

• Endpoint type: Continuous: a mean value per participant, compared as a difference in means.
• Test: Unadjusted two-sample z-test for the difference in means, using the posted standard deviations.
• Result:
  • No Treatment: mean 1.32 versus 10.00 on control; difference -8.68 (95% CI -13.56 to -3.81), standardized effect d = -1.18; z-test p = <0.001.
• Interpretation:
  • The 95% confidence interval excludes no difference, so the mean is statistically lower for No Treatment than for the control. This is an unadjusted, secondary comparison, so it is suggestive rather than confirmatory.

The registry lists one secondary outcome: change from baseline for the Yeaple Probe, measured at 10 Minutes. Its posted group summaries and comparison have a different statistical pattern from the primary air-challenge outcome: the secondary comparison interval is entirely below zero and its unadjusted p-value is <0.001, while the primary comparison interval includes zero and its unadjusted p-value is 0.08.

The secondary measure can add another perspective on the study's recorded outcomes, but the registry does not explain how a positive or negative change on the Yeaple Probe relates to sensitivity. It also does not report a prespecified hierarchy placing the secondary outcome in relation to the primary endpoint. It is therefore appropriate to describe the numerical pattern without assuming that it confirms, contradicts, or replaces the primary result.

Unadjusted secondary results carry less weight when several outcomes or comparisons may have been examined. Multiple testing increases the opportunity for an apparently strong result to arise by chance, and an adjustment or prespecified testing sequence can help address that concern. The record does not report whether multiplicity was considered in the trial's analysis plan, whether additional outcomes were analyzed but not posted, or whether the secondary outcome was intended as confirmatory or exploratory.

The registry lists two outcome measures in total, with one secondary outcome posted, and reports no analyses. These registry entries do not establish what analyses were planned or how outcome selection was handled. The secondary finding should therefore be considered alongside the primary estimate, the unadjusted nature of the result, the absent multiplicity details, and the lack of a registry description of the secondary scale's direction. It should not be treated as a standalone conclusion about the intervention.

Secondary outcomes registered for this trial, for reference (only those above were recalculated):

• Change From Baseline for Yeaple Probe

9. Statistical Interpretation

10. Statistical Methods Explained

The posted outcomes are continuous measures summarized by group means and standard deviations. A mean describes the arithmetic average of the recorded change values, while a standard deviation describes how dispersed individual values are around that mean. These summaries provide a compact account of the observed groups, but they do not reveal the full shape of the outcome distribution or whether some subjects had markedly different responses.

What does the mean difference represent?

The primary comparison is expressed as the no-treatment mean minus the oxalate salt solution mean. The reported estimate of 0.28 is therefore a contrast between the groups' mean changes, not a change within either group. The sign depends on the stated subtraction order. For the primary measure, the outcome definition also says that negative change from baseline represents a decrease in sensitivity. Keeping the comparison order and the scale's direction in view prevents confusing a between-group contrast with a group's change from baseline.

The Yeaple Probe comparison uses the same displayed order, no treatment minus oxalate salt solution. Its estimate is -8.684. The registry labels this outcome as a mean change in units on a scale but does not provide a direction note explaining what a positive or negative change signifies for sensitivity. The numerical contrast can be described, but its substantive direction should not be inferred from the primary measure's scale description.

How should a confidence interval be read?

A confidence interval describes a range of values compatible with the estimate under the method used to calculate it. It conveys uncertainty about the group contrast, not the range of individual subject outcomes. A narrower interval indicates greater precision than a wider one, all else equal. The registry gives interval limits for both comparisons, but does not report the confidence level or all details of the interval calculation. Interpretation should therefore use the posted limits without assuming an unreported confidence level.

For the primary comparison, the interval runs from -0.033 to 0.593 and crosses zero. This indicates uncertainty about whether the population contrast is below or above zero. For the secondary comparison, the interval runs from -13.56 to -3.813 and is entirely below zero. That describes a more directionally consistent estimate under the posted interval, but it does not address multiplicity or establish clinical importance. The record does not define a threshold for a meaningful change on either measure.

What does an unadjusted p-value tell the reader?

A p-value is a measure of how unusual the observed result, or a more extreme result, would be under a specified null model. It is not the probability that the null hypothesis is true, nor does it describe the size or practical importance of an effect. The primary comparison's unadjusted p-value is 0.08; the secondary comparison's unadjusted p-value is <0.001. Because they are unadjusted, these values do not account for testing multiple outcomes or comparisons. The registry record does not report whether any multiplicity adjustment was planned or performed.

The record lists no reported analyses, even though it posts outcome summaries and comparisons. It does not describe whether the comparisons were prespecified, which analysis population was used, how missing observations were handled, or whether any adjustment for baseline factors was made. The reported estimates can be interpreted as posted group summaries and contrasts, but a fuller assessment of the analysis requires those details.

Why does dispersion matter?

Standard deviations provide context for variability around the group means. When outcomes are variable relative to the mean difference, it can be harder to estimate the contrast precisely. In some settings, over-dispersion means variability is greater than a statistical model expects; that can make model-based standard errors and intervals too optimistic if the model does not allow for the extra variability. The registry does not report an over-dispersion assessment or a model-based adjustment. The displayed standard deviations and intervals should be read as the posted summaries, not as evidence that a particular variance model was checked.

These explanations are general statistical concepts. For this trial, the original statistical plan, confidence level, missing-data approach, and analysis-population definition are not reported in the registry record. Those unknowns matter when judging whether the posted summaries match the intended analysis and how far their uncertainty statements can be generalized.

11. Confidence Intervals and Precision

Precision concerns how much uncertainty surrounds an estimated group contrast. The primary mean difference is 0.28, with interval limits of -0.033 and 0.593. Because the interval crosses zero, the posted estimate is compatible with a small contrast in either direction as well as a positive contrast. The interval gives more information than the point estimate alone, but the registry does not report the confidence level or the full method used to construct it.

The secondary mean difference is -8.684, with interval limits of -13.56 and -3.813. This interval lies below zero, so the values compatible with that posted interval share the same numerical sign. It is still an interval for a group mean contrast, not a range that contains a particular proportion of individual participant outcomes. The record also does not state what size of change would be clinically important for either measure.

The primary outcome group standard deviations are 0.537 for oxalate salt solution and 0.403 for no treatment. For the Yeaple Probe outcome, the corresponding standard deviations are 8.101 and 6.634. These figures describe variability in the posted groups and help put each mean in context; they do not remove uncertainty caused by the participant counts or missing methodological detail.

The primary outcome counts are 17 and 19. The available precision should therefore be understood in the context of those observed group sizes, rather than as a guarantee that a similar estimate would be obtained in another sample. The registry does not report the originally intended sample size, the rationale for it, or an allowance for incomplete outcome data. The interval estimates are informative about statistical uncertainty under their calculation method, but they do not address possible bias from study conduct or outcome selection.

12. Planning a Similar Trial: Sample Size

This is a planning illustration, not a re-evaluation of the original trial. It asks: if a new study wanted to detect a difference like the one observed, or a smaller one, how large would it need to be? It is deliberately not “observed power” of the finished trial, which is not a meaningful quantity.

The planning figures are participants per arm, not total events. They are illustrative calculations based on the observed effect and are not the trial's original design justification. The listed assumptions are a two-sided significance level of 0.05, equal allocation between the two arms, and a normal approximation. The figures show the participant count per arm associated with 80% power and 90% power for the stated fraction of the observed effect.

Power is the probability that a study would detect an effect of a specified size under the assumptions used, if that effect were the true one. The 80% column means the planned sample size is associated with an 80% chance of detecting the chosen effect under the calculation assumptions; the 90% column represents a higher chance under those assumptions. These are planning illustrations, not observed power, and do not establish what power the completed trial actually had.

The rows consider planning for 100% of the observed effect, 75% of the observed effect, and 50% of the observed effect. For 100% of the observed effect, the figures are 45 participants per arm for 80% power and 60 for 90% power. For 75% of the observed effect, they are 79 and 106 participants per arm, respectively. For 50% of the observed effect, they are 178 and 238 participants per arm, respectively. The pattern illustrates the general planning principle that smaller effects require more participants to detect, when the other assumptions remain the same.

The registry does not report the trial's original sample-size assumptions or justification. The planning figures are therefore best read as hypothetical illustrations derived from the posted effect estimate, not as evidence that the trial was designed to reach a particular power or that its observed results had a particular probability of being detected.

13. How the Sample Size Is Derived

Power is the probability that a study of a given size rejects the null hypothesis when a specific true effect exists. It depends on four things: the effect to detect, the variability of the outcome, the significance level (here a two-sided α of 0.05, so z_1−α/2 = 1.960) and the desired power (z_1−β = 0.842 for 80% and 1.282 for 90%).

Formula

n is the number of participants in each arm, Δ is the difference in means to detect and σ is the common standard deviation.

Worked calculation for this trial

1. Observed difference Δ = 0.280; pooled standard deviation σ = 0.471.
2. n = 2 × (1.96 + 0.842)² × 0.471² / 0.280² = 44.4, rounded up to 45 participants per arm for 80% power.

The smaller-effect rows in the table above repeat the same calculation with the effect multiplied by 0.75 and 0.5 (for ratios, applied to the logarithm of the ratio).

R code

alpha <- 0.05
z_a   <- qnorm(1 - alpha / 2)          # two-sided
delta <- 0.28                      # observed difference in means
sigma <- 0.470833616172048                     # pooled standard deviation
n_per_arm <- function(power, frac = 1) {
  ceiling(round(2 * (z_a + qnorm(power))^2 * sigma^2 / (delta * frac)^2, 6))
}
for (f in c(1, 0.75, 0.5))
  cat(sprintf("%3.0f%% of observed effect: n per arm = %s (80%% power), %s (90%% power)\n", 100 * f,
              format(n_per_arm(0.80, f), big.mark = ","), format(n_per_arm(0.90, f), big.mark = ",")))

# Check against R's built-in function (t-based, so very slightly larger)
cat("power.t.test:", round(power.t.test(delta = delta, sd = sigma, power = 0.80)$n, 1), "\n")

# Simulation: exact two-sample t-test using simulated means and variances
set.seed(2481557)
n    <- n_per_arm(0.80)
reps <- 20000
m_diff <- rnorm(reps, delta, sigma * sqrt(2 / n))             # difference in sample means
s2     <- sigma^2 * rchisq(reps, 2 * (n - 1)) / (2 * (n - 1))   # pooled sample variance
tstat  <- m_diff / sqrt(s2 * 2 / n)
cat(sprintf("Simulated power at n = %s per arm: %.3f (%d replicates)\n", format(n, big.mark = ","), mean(abs(tstat) > qt(0.975, 2 * (n - 1))), reps))

Output from running the code

100% of observed effect: n per arm = 45 (80% power), 60 (90% power)
 75% of observed effect: n per arm = 79 (80% power), 106 (90% power)
 50% of observed effect: n per arm = 178 (80% power), 238 (90% power)
power.t.test: 45.4 
Simulated power at n = 45 per arm: 0.799 (20000 replicates)

The simulation draws many sets of group means and variances at the planned sample size and counts how often the two-sample t-test rejects the null. It should land close to the target power; at very small required sample sizes it can fall below it, because the normal approximation is rough there.

14. Multiplicity, Missing Data and Analysis Populations

Multiplicity arises when a study assesses multiple outcomes, comparisons, time points, or subgroups. If each is tested separately without accounting for the family of tests, the chance of obtaining at least one apparently notable result can increase. A prespecified primary outcome and a clear strategy for secondary outcomes can help readers understand which findings were intended to carry the strongest confirmatory weight.

The registry identifies change from baseline in air-challenge response as the primary outcome and change from baseline for the Yeaple Probe as a secondary outcome. The posted comparisons are described as unadjusted. A multiplicity adjustment, testing hierarchy, or other method for controlling the interpretation of multiple results is not reported in the registry record. The record also does not explain whether the listed outcomes were the full set planned or whether there were additional analyses that were not posted.

Missing-data methods are not reported. Although the registry states that Thirty-Six (36) subjects received products and completed the study, it does not explain whether all completed subjects contributed to each endpoint, how unavailable measurements were handled, or whether any outcome values were imputed. The primary outcome counts are 17 and 19, while the adverse-event denominators are listed separately by event category. The record does not explain these denominator choices or any relationship between them and endpoint availability.

The analysis population is also not defined. The record does not state whether results use all randomized participants, participants who received treatment, participants who completed the study, or another set. Nor does it report a protocol-deviation policy or whether outcomes were analyzed according to randomized assignment. These omissions make it difficult to evaluate the effect of exclusions or missing measurements on the posted estimates.

These are reporting gaps, not proof that a particular method was or was not used. Without the analysis plan and additional details, readers cannot determine whether multiplicity and missingness were handled in a way that preserves the intended interpretation of the results.

15. 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 zero serious adverse events in the oxalate salt solution group among 17 participants listed at risk and zero in the no-treatment group among 17 participants listed at risk for serious events. It reports zero other adverse events among 17 participants at risk in the oxalate group and zero among 19 at risk in the no-treatment group. Deaths are reported as zero in each group. No serious adverse event terms are listed.

The serious-event denominator for no treatment is listed as 17, whereas the primary outcome group count and the other-adverse-event denominator for that arm are 19. The registry does not explain this difference, so the denominators should be read as recorded rather than reconciled by assumption. Zero reported events means none are listed in these categories for the stated at-risk groups; it does not establish the absence of all possible harms.

These figures describe what the registry reports for this trial and its recorded observation period. The record does not provide detailed event definitions, event-collection procedures, exposure duration beyond the outcome timeframe, or a fuller safety analysis. The small participant counts also mean that these event summaries cannot characterize uncommon events reliably. They should be interpreted as descriptive counts, not as proof of safety or a comparison capable of excluding risk.

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

The primary results describe a mean change in Schiff Sensitivity Scale response after an air challenge at 10 Minutes. The oxalate salt solution group's mean change was -0.412, and the no-treatment group's mean change was -0.132. The registry defines negative change as a decrease in sensitivity from baseline. The reported between-group mean difference was 0.28, with an interval from -0.033 to 0.593 and an unadjusted p-value of 0.08.

Those results show the observed group summaries and the uncertainty attached to the primary contrast. The interval crosses zero, so it does not pin down the direction of the underlying between-group contrast. The p-value is unadjusted and should not be interpreted as the probability that a treatment effect exists or does not exist. Neither statistic establishes clinical importance, which the registry does not define for this measure.

The secondary Yeaple Probe result has a different pattern, but the registry does not describe the clinical direction of change for that scale, and the result is unadjusted. It therefore adds information about a separate recorded measure without resolving the uncertainty in the primary comparison. The absence of a reported multiplicity plan and analysis details further limits the strength of conclusions drawn from the secondary finding.

The results do not establish what would occur in a different population, under a different application procedure, or beyond the recorded assessment timeframe. The record does not provide detailed eligibility criteria, a full statistical plan, or enough information to assess missing data and analysis-population choices. The trial was randomized, but no masking was listed, and the registry does not report who knew assignment during assessment.

Overall, the posted values are estimates from a completed, small parallel-group trial. They describe measured responses in the recorded groups and their statistical uncertainty. They should not be converted into medical advice or treated as a definitive judgment about whether the intervention works or does not work.

17. Why This Trial Matters Statistically

This trial illustrates why a group mean and a between-group contrast answer different questions. Both groups had negative mean change on the Schiff air-challenge measure, while the primary comparison estimates the difference between those group changes. The scale's direction note is essential: a negative within-group change represents decreased sensitivity, but the contrast's sign depends on the subtraction order used to report it.

It also shows why estimates should be read with their intervals. The primary estimate is 0.28, but its interval extends across zero, so the point estimate alone gives an incomplete picture. The secondary comparison has a more directionally consistent interval, yet its unadjusted status and the absence of a reported multiplicity strategy affect how much confirmatory weight it can carry. A small p-value is not a substitute for a clear analysis plan or a measure of clinical importance.

The record also highlights the difference between planning illustrations and the original design. Sample-size figures based on an observed effect can help show how assumptions about effect size and desired power relate to participant needs. They do not document why this trial enrolled its participants or establish its observed power. The trial's own sample-size justification is not reported.

Finally, statistical interpretation depends on more than the values in an outcome summary. Definitions of the analysis population, handling of missing measurements, multiplicity methods, and details of outcome collection all help determine what an estimate can support. Several of these details are not reported for this trial. Recognizing those limits is part of interpreting the numerical results responsibly, rather than treating a single result as a complete account of the evidence.

18. 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 registry leaves several trial-specific details unreported. Eligibility criteria beyond dentin sensitivity, participant characteristics, baseline outcome distributions, and the number of test teeth contributing to each participant's result are not described. Without those details, readers cannot assess how closely the enrolled subjects or recorded teeth represent other settings.

The study was listed as having no masking. The record does not say which people knew assignment or whether outcome assessment involved safeguards against knowledge of treatment. Because the primary endpoint relies on an examiner-recorded response, the absence of masking is relevant context, although the registry does not provide enough detail to determine its effect on measurement.

The registry does not report a detailed application protocol, the original sample-size rationale, a statistical analysis plan, interim analyses, or a definition of the analysis population. It also does not explain missing-measurement handling, outcome exclusions, or whether comparisons were adjusted for baseline values. These gaps limit evaluation of prespecification and analytic choices.

The primary endpoint is reported as a mean change in a scored scale, but the record does not provide a threshold for a clinically meaningful difference or the distribution of individual responses. The Yeaple Probe outcome has no registry description of the meaning of positive and negative change. Its unadjusted comparison should be interpreted with that uncertainty and the absence of a reported multiplicity plan in mind.

Lastly, safety denominators differ between the serious-event and other-adverse-event listings for the no-treatment group, and the record does not explain why. The recorded event counts are descriptive and come from a limited set of participants. These limitations do not invalidate the posted results, but they narrow the conclusions that can be drawn from them.

19. Related Tutorials

20. Related Statistical Calculators

21. Sources

• ClinicalTrials.gov: Effects of an Oxalate Containing Product on Dentinal Hypersensitivity With Dental Prophylaxis — NCT02481557.
• Registry record last updated 2019-06-11; status last verified 2019-05.
• Results first posted 2019-05-29.
• 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.

22. Record Summary

The registry record describes NCT02481557, a completed randomized, open-label parallel trial of a professionally applied oxalate salt solution versus no treatment for dentin sensitivity. Enrollment was 36, and the record states that Thirty-Six (36) subjects received products and completed the study. The recorded start and primary completion dates are both 2015-06.

The primary outcome was change from baseline in Schiff Sensitivity Scale response to an evaporative air challenge at 10 Minutes. The posted mean difference was 0.28, with an interval from -0.033 to 0.593 and an unadjusted p-value of 0.08. One secondary outcome, change from baseline for the Yeaple Probe at 10 Minutes, was also posted. Its unadjusted comparison had an interval from -13.56 to -3.813 and a p-value of <0.001.

The registry reports zero serious adverse events, zero other adverse events, and zero deaths in the listed groups. Detailed analysis methods, multiplicity handling, missing-data procedures, and the trial's original sample-size justification are not reported in the registry record.