This page provides an independent statistical analysis and educational interpretation of publicly reported results. ClinicalTrials.gov provides the official trial registry record. Numerical trial results on this page are restricted to the results posted in the ClinicalTrials.gov record; calculations added by Clinical Biostats are labelled as such.
1. Trial at a Glance
This page covers the registry results for DryShield vs Cotton Roll Isolation During Sealants Placement: Efficiency and Patient Preference (NCT02995369), a randomized na study. The primary outcome is Placement Time of Sealants Using Dryshield (DS) vs Cotton Rolls (CRI).
| Feature | Registry value |
|---|---|
| ClinicalTrials.gov identifier | NCT02995369 |
| Phase | NA |
| Condition | Time, Patient Preference |
| Allocation | Randomized |
| Design model | Crossover |
| Masking | None (open label) |
| Enrollment | 32 |
| Arms in the primary outcome | 4 |
| Lead sponsor | Montefiore Medical Center |
| Results posted | Yes |
2. Clinical Question
Population
The registry record lists an enrollment of 32. Participants received sealants on teeth on both sides of the mouth, with the isolation technique and side/order varying across the randomized groups. Further participant characteristics are not reported in the registry record.
Intervention
DryShield isolation was used while sealants were placed on one side of the mouth. The registry describes DryShield as a device. Placement time began when the isolation aid was inserted and ended when that aid was removed after sealant application.
Comparator
Cotton roll isolation was used for sealant placement on the opposite side. The registry describes four groups reflecting which side received each technique and which technique was administered first. The study was randomized and used a crossover model.
Primary question
The primary question was whether the time for sealant application differed between DryShield and cotton roll isolation. The registry also identifies patient preference as a study goal, but no preference results are reported in the registry record. The posted timing summaries are organized by side and sequence, so they should be read as group-level summaries rather than as a reported paired treatment-effect analysis.
3. Trial Design
This was a completed randomized crossover study sponsored by Montefiore Medical Center. Enrollment was 32. The registry lists the study start as 2017-01-17 and primary completion as 2017-03-23. The study was not masked. Phase is listed as NA.
In the crossover arrangement, participants received sealant placement using both cotton roll isolation and DryShield, with the techniques applied on opposite sides of the mouth. The four group descriptions vary which side received each technique and which technique was used first. Randomization therefore concerned the side and order of the techniques, as reflected in the group descriptions. The registry does not report further details about sequence generation, allocation concealment, or how the crossover was handled in the analysis.
The primary outcome was placement time in seconds. The measurement started with insertion of the first isolation aid and ended when the corresponding aid was removed after sealant application. A dental assistant recorded the time with a stopwatch. Results were analyzed and reported based on the sequence in which interventions were administered, according to the outcome description.
The registry lists two study goals: comparing placement time and assessing patient preference. It reports timing summaries, but patient-preference results are not reported in the registry record. Details of participant eligibility, recruitment, follow-up, and the trial's original sample-size rationale are also not reported in the registry record.
4. Participant Flow and Accounting
The registry reports how participants moved through each stage of the study. All counts below are exactly as posted; missing counts are not inferred from other stages.
Overall Study
| Stage | Cotton Roll Isolation (Left) First, Then Dryshield Isolation (Right) | Cotton Roll Isolation (Right) First, Then Dryshield Isolation (Left) | Dryshield Isolation (Left) First, Then Cotton Roll Isolation (Right) | Dryshield Isolation (Right) First, Then Cotton Roll Isolation (Left) |
|---|---|---|---|---|
| STARTED | 8 | 8 | 8 | 8 |
| COMPLETED | 8 | 8 | 8 | 8 |
| NOT COMPLETED | 0 | 0 | 0 | 0 |
Analysis population for the primary outcome, as defined in the registry: Results were analyzed and reported based on the sequence the interventions were administered.
5. Baseline Characteristics
The table reproduces the baseline characteristics posted in the registry, which describe the participants analysed at baseline and help show whether the randomized groups were comparable.
| Characteristic | Unit | Cotton Roll Isolation (Left) First, Then Dryshield Isolation (Right) | Cotton Roll Isolation (Right) First, Then Dryshield Isolation (Left) | Dryshield Isolation (Left) First, Then Cotton Roll Isolation (Right) | Dyshield Isolation (Right) First, Then Cotton Roll Isolation (Left) | Total |
|---|---|---|---|---|---|---|
| Participants analysed | 8 | 8 | 8 | 8 | 32 | |
| Age, Continuous | years | 8.6 (7 to 10) | 8.6 (6 to 11) | 8.8 (6 to 13) | 8.5 (6 to 12) | 8.6 (6 to 13) |
| Sex/Gender, Customized: Unknown | Participants | 8 | 8 | 8 | 8 | 32 |
| Race and Ethnicity Not Collected | Participants | — | — | — | — | 0 |
| Region of Enrollment: United States | participants | 8 | 8 | 8 | 8 | 32 |
6. Primary Endpoint
The registry lists the primary outcome as Placement Time of Sealants Using Dryshield (DS) vs Cotton Rolls (CRI), measured over Initial insertion of isolation aid (CRI or DS) and removal of corresponding isolation aid (CRI or DS).
| Element | Registry entry |
|---|---|
| Result type | Mean |
| Measure of spread | Standard Deviation |
| Unit | Seconds |
| Endpoint classification | Continuous Endpoint |
The primary endpoint is the time required for sealant application using an isolation technique, measured in seconds. The recorded interval begins when the isolation aid is inserted into the oral cavity and ends when that same aid is removed after sealant application. The dental assistant measured the interval with a stopwatch. The registry reports the mean and standard deviation for the groups.
Timing is relevant to the stated efficiency question because it quantifies the duration of the sealant-placement process under each isolation approach. It is a continuous measure: each participant's time can take values across a range rather than being limited to categories. The mean describes the group's average time, while the standard deviation describes the spread of individual times around that average.
The outcome description says results were analyzed and reported according to intervention sequence. That distinction matters in a crossover study because side and order may be related to the reported group summaries. The registry record does not report a participant-level paired estimate that directly accounts for each person's measurements under both techniques. Patient preference is a separate stated goal, not part of this primary timing endpoint, and preference results are not reported in the registry record.
7. Results Posted in the Registry
- Cotton Roll Isolation (Right): mean 160.50 versus 164.88 on control; difference -4.38 (95% CI -23.38 to 14.62), standardized effect d = -0.16; z-test p = 0.651.
- Dryshield Isolation (Left): mean 164.56 versus 164.88 on control; difference -0.32 (95% CI -19.90 to 19.26), standardized effect d = -0.01; z-test p = 0.974.
- Dryshield Isolation (Right): mean 167.81 versus 164.88 on control; difference 2.93 (95% CI -17.06 to 22.92), standardized effect d = 0.10; z-test p = 0.774.
Mean difference: Cotton Roll Isolation (Right)
95% CI: -23.38 to 14.62
Recalculated from the posted summary statistics
8. Statistical Interpretation
The reported mean times are close across the four side-specific groups. Cotton Roll Isolation (Left) had a mean of 164.9 seconds, with a standard deviation of 28.78. Cotton Roll Isolation (Right) had a mean of 160.5 seconds, with a standard deviation of 26.0. Dryshield Isolation (Left) had a mean of 164.6 seconds, with a standard deviation of 27.72. Dryshield Isolation (Right) had a mean of 167.8 seconds, with a standard deviation of 28.92.
The registry-derived comparisons use Cotton Roll Isolation (Left), whose mean was 164.9 seconds, as the reference group. The mean difference for Cotton Roll Isolation (Right) was -4.38 seconds, with a 95% confidence interval from -23.38 to 14.62 and an unadjusted p-value of 0.651. The mean difference for Dryshield Isolation (Left) was -0.32 seconds, with a 95% confidence interval from -19.9 to 19.26 and an unadjusted p-value of 0.974. The mean difference for Dryshield Isolation (Right) was 2.93 seconds, with a 95% confidence interval from -17.06 to 22.92 and an unadjusted p-value of 0.774.
Each interval includes zero, meaning the reported results are compatible with a range of differences in either direction under the stated unadjusted comparisons. The p-values do not provide strong evidence against a zero mean difference in these comparisons, but they do not establish that the techniques have identical timing. The confidence intervals are wide relative to the point estimates, so the registry summaries allow substantial uncertainty about the size and direction of a difference.
These are simple comparisons of reported group summaries, not a reported analysis that accounts for the crossover structure or uses within-participant pairing. Side, sequence, and the correlation between measurements from the same participant could matter for a crossover analysis. The registry record does not report an adjusted model or a paired treatment-effect estimate. Consequently, the numerical contrasts should be read as descriptive and unadjusted, rather than as definitive estimates from a fully specified crossover model.
The registry identifies patient preference as a goal, but preference findings are not reported in the registry record. Thus, the posted results address timing only. They do not show how participants rated either technique or whether preferences differed by technique.
9. Statistical Methods Explained
The posted continuous-outcome summaries give group means and standard deviations, alongside unadjusted mean differences, confidence intervals, and p-values. The displayed contrasts compare each listed group with Cotton Roll Isolation (Left). The registry record does not report a formal statistical analysis plan or a model that incorporates the crossover structure.
What does a mean describe?
In general, a mean is the arithmetic average of observations in a group. For this endpoint, it describes the average number of seconds from insertion of an isolation aid to its removal after sealant application. A mean is useful for describing the typical level of a continuous outcome, but it does not show the range of individual observations or whether times were concentrated near the average. The standard deviation gives a separate description of variability: a larger standard deviation indicates more spread around the group mean. It is not the uncertainty in the estimated mean; that uncertainty is reflected by a confidence interval.
The four reported means are 164.9 seconds for Cotton Roll Isolation (Left), 160.5 seconds for Cotton Roll Isolation (Right), 164.6 seconds for Dryshield Isolation (Left), and 167.8 seconds for Dryshield Isolation (Right). Their accompanying standard deviations are 28.78, 26.0, 27.72, and 28.92, respectively. These summaries describe the individual listed groups. They are not, on their own, a direct estimate of the within-participant difference between techniques.
What does a mean difference represent?
In general, a mean difference expresses the difference between the average outcome in one group and the average outcome in a reference group. A negative estimate means the compared group's mean is lower than the reference mean; a positive estimate means it is higher. Here, the comparisons use Cotton Roll Isolation (Left) as the reference. For example, the reported estimate for Dryshield Isolation (Right) is 2.93 seconds, reflecting its mean of 167.8 seconds compared with the reference mean of 164.9 seconds. The reported estimate for Dryshield Isolation (Left) is -0.32 seconds.
These contrasts are unadjusted summary-statistic comparisons. In general, an unadjusted comparison does not account for other design features or variables through a model. Because this study is a crossover, measurements under different techniques may come from the same participant and therefore may be correlated. A paired analysis can use the within-participant relationship; a comparison treating groups as independent does not make that adjustment. The registry record does not report a paired analysis, a crossover model, or adjustments for sequence or side. The reported contrasts should therefore not be interpreted as if those features had been modeled.
What do the p-values tell a reader?
In general, a p-value measures how incompatible the observed data are with a specified null hypothesis, under the statistical assumptions used for the calculation. A large p-value is not proof that the null hypothesis is true, and it does not give the probability that the treatments are identical. The unadjusted p-values reported for the three contrasts are 0.651, 0.974, and 0.774. They do not by themselves establish equivalence or rule out potentially meaningful differences. Interpretation also depends on the estimated effects, their confidence intervals, and the validity of the analysis assumptions.
The p-values are labeled unadjusted. The registry record does not report a multiplicity adjustment or a prespecified testing hierarchy for the group contrasts. When several comparisons are considered, the chance of at least one apparently unusual result can differ from that for a single prespecified comparison. This is a general concern; the registry does not state how multiplicity was addressed.
Why does the crossover structure matter?
In general, a crossover design exposes the same participant to more than one intervention. This can allow a comparison that accounts for stable differences between participants, but it also requires attention to paired measurements, treatment order, and possible period or carryover effects when relevant. The registry descriptions indicate that both techniques were used on opposite sides and that the sequence and side varied. The outcome description says results were reported by sequence. The record does not provide the participant-level data or describe how within-participant dependence, sequence, side, or period effects were handled. These omissions limit what can be inferred from the simple reported contrasts.
The registry lists 32 enrolled participants and reports 16 observations in each displayed group summary. These group counts should be interpreted in the context of the crossover and sequence descriptions; they should not be added together to infer a number of distinct participants. The registry record does not report the number contributing paired observations to a particular analysis, exclusions from the analysis, or how missing measurements were handled.
In general, the calculation of an interval or test also relies on assumptions about the data and sampling process. Details such as distributional checks, transformations, model specification, and robust or alternative methods are not reported in the registry record. This means the posted unadjusted comparisons can be described and their numerical uncertainty discussed, but the assumptions behind a sponsor's original analysis cannot be evaluated from the registry entry.
10. Confidence Intervals and Precision
The confidence intervals quantify uncertainty around the reported mean differences under the calculations used. In general, a confidence interval gives a range of values compatible with the data and method; it is not a guarantee that the true effect lies within the particular interval. Its width reflects both the variability in the observations and the amount of information available for the estimate.
For Cotton Roll Isolation (Right) compared with Cotton Roll Isolation (Left), the estimated mean difference is -4.38 seconds and the 95% confidence interval is -23.38 to 14.62 seconds. For Dryshield Isolation (Left) compared with Cotton Roll Isolation (Left), the estimate is -0.32 seconds and the interval is -19.9 to 19.26 seconds. For Dryshield Isolation (Right) compared with Cotton Roll Isolation (Left), the estimate is 2.93 seconds and the interval is -17.06 to 22.92 seconds.
All three intervals include zero and extend to values on both sides of zero. Thus, the estimates are not precise enough to establish a direction of difference from these unadjusted contrasts. The intervals also include differences that are considerably larger in magnitude than the point estimates. No threshold for a clinically or practically important timing difference is reported in the registry record, so the intervals cannot be classified against a registry-stated threshold.
The intervals are based on the posted group-summary comparisons, not a reported paired crossover model. In general, a method that accounts for within-participant correlation can yield different uncertainty estimates from one that treats groups as independent. Since the registry record does not describe such modeling, the intervals should be understood as the uncertainty from the displayed unadjusted calculations, not as proof that all relevant design features have been addressed.
11. 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.
| Effect to detect | Participants per arm, 80% power | Participants per arm, 90% power |
|---|---|---|
| 100% of the observed effect | 616 | 824 |
| 75% of the observed effect | 1,095 | 1,465 |
| 50% of the observed effect | 2,462 | 3,296 |
The planning figures are illustrations based on the observed effect, not the trial's original design assumptions. The original sample-size rationale and design assumptions are not reported in the registry record. These planning calculations use a two-sided significance level of 0.05, equal allocation between two arms, and a normal approximation. For each scenario, the effect to detect is set to the stated fraction of the observed effect. The figures are participants per arm, not total participants or total events; the event-count convention for time-to-event outcomes does not apply to this continuous timing outcome.
The 80% power column describes the number of participants per arm estimated to give an 80% chance of detecting the assumed effect under those planning assumptions, if the assumed effect and model are correct. The 90% power column gives the corresponding planning estimate for a 90% chance. These are planning interpretations, not guarantees about what a future study would find. This is not observed power.
The scenarios are labeled as planning for 100%, 75%, and 50% of the observed effect. A smaller target effect is harder to distinguish from random variation, so it requires more participants under the same assumptions. The resulting estimates can be very large when the observed effect used for planning is small. They should not be taken as a retrospective judgment about the adequacy of the enrolled sample, nor as evidence that the trial was designed around the calculation. The registry's original sample-size justification is not reported.
12. 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 z1−α/2 = 1.960) and the desired power (z1−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
- Observed difference Δ = -4.380; pooled standard deviation σ = 27.425.
- n = 2 × (1.96 + 0.842)2 × 27.4252 / -4.3802 = 615.4, rounded up to 616 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 <- -4.38 # observed difference in means
sigma <- 27.4252474920464 # 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(2995369)
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 = 616 (80% power), 824 (90% power)
75% of observed effect: n per arm = 1,095 (80% power), 1,465 (90% power)
50% of observed effect: n per arm = 2,462 (80% power), 3,296 (90% power)
power.t.test: 616.4
Simulated power at n = 616 per arm: 0.800 (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.
13. Multiplicity, Missing Data and Analysis Populations
The registry record does not report a prespecified multiplicity strategy, a hierarchy of hypotheses, or an adjustment for testing several comparisons. The posted timing contrasts are unadjusted. In general, considering multiple comparisons can raise the chance of a false-positive finding across the set of tests, so readers need to know whether comparisons were planned and how the analysis handled them. That information is not reported in the registry record. The presence of unadjusted p-values alone does not establish that the comparisons were prespecified or that multiplicity was controlled.
The record identifies patient preference as a study goal, but preference results are not reported in the registry record. It also does not report secondary outcome results. Therefore, the posted timing summaries do not answer the preference question, and there is no basis in the registry entry to assess whether missing preference results reflect noncollection, nonanalysis, or another reason.
Missing-data methods and the amount or pattern of missing outcome data are not reported in the registry record. The number included in each displayed timing summary is listed as 16, but the record does not explain whether any enrolled participant lacked a measurement, how incomplete crossover observations were treated, or whether participants were excluded from analyses. The analysis population is not described as intention-to-treat, per-protocol, or another defined set.
For a crossover study, incomplete observations can affect whether both treatment measurements are available for a participant. In general, a paired analysis requires usable observations under both conditions for the relevant participant-level contrast, while other approaches may use incomplete records under stated assumptions. The registry does not say which approach was used. It also does not report a formal statistical analysis plan, a detailed model, or sensitivity analyses. These gaps limit assessment of how missingness, multiplicity, and analysis-set choices might affect the reported results.
14. Safety Results
The registry reports serious adverse events as affected participants divided by participants at risk.
| Arm | Participants with serious adverse events | Participants at risk | Percentage |
|---|---|---|---|
| Cotton Roll Isolation (Left) | 0 | 16 | 0.0% |
| Cotton Roll Isolation (Right) | 0 | 16 | 0.0% |
| Dryshield Isolation (Left) | 0 | 16 | 0.0% |
| Dryshield Isolation (Right) | 0 | 16 | 0.0% |
Deaths
| Arm | Deaths (participants affected of at risk) |
|---|---|
| Cotton Roll Isolation (Left) | 0 of 16 |
| Cotton Roll Isolation (Right) | 0 of 16 |
| Dryshield Isolation (Left) | 0 of 16 |
| Dryshield Isolation (Right) | 0 of 16 |
Other (non-serious) adverse events
Participants with at least one non-serious event at or above the registry's 0% reporting threshold.
| Arm | Participants affected of at risk |
|---|---|
| Cotton Roll Isolation (Left) | 0 of 16 |
| Cotton Roll Isolation (Right) | 0 of 16 |
| Dryshield Isolation (Left) | 0 of 16 |
| Dryshield Isolation (Right) | 0 of 16 |
The adverse-event record lists 16 participants at risk in each of the four group entries. For Cotton Roll Isolation (Left), Cotton Roll Isolation (Right), Dryshield Isolation (Left), and Dryshield Isolation (Right), the serious adverse event count is 0 and the other adverse event count is 0. Deaths are listed as 0 for each group. No serious adverse event terms are listed.
These figures describe the events recorded in the registry for the displayed groups. They should not be read as evidence that no events of any kind occurred outside what was recorded, or as proof of absence of risk. The registry record does not provide further detail about event definitions, collection procedures, surveillance duration, or how crossover exposure was handled in safety reporting. The listed at-risk counts are group entries in a crossover study and should not be summed to infer the number of distinct participants.
15. What the Result Does, and Does Not, Mean
The posted results describe sealant-placement times in the four listed side and sequence groups. Their mean times range from 160.5 seconds to 167.8 seconds, and the three unadjusted mean-difference intervals each include zero. The estimates are small relative to the uncertainty represented by their intervals, which extend in both directions. This pattern indicates that the posted summaries do not precisely determine whether one technique took longer than the other.
That is not the same as demonstrating that the techniques have identical placement times. A conclusion of equivalence would require a defined margin and an analysis designed to assess whether plausible differences fall within it. Neither an equivalence margin nor such an analysis is reported in the registry record. Likewise, a non-significant p-value is not proof of no difference.
The comparisons are reported by group and use Cotton Roll Isolation (Left) as the reference. The record does not report a paired crossover model, adjustment for sequence or side, or a formal analysis plan. Therefore, the results should be interpreted as descriptive, unadjusted contrasts rather than definitive estimates that account for every feature of the design. The registry record also does not report a threshold for a meaningful difference in seconds.
The study's other stated goal was patient preference. Because preference results are not reported in the registry record, the timing summaries do not establish which technique participants preferred. The recorded adverse-event summaries list zero serious events, zero other events, and zero deaths in each group, but the registry entry does not describe event ascertainment in greater detail. Overall, the available record supports a cautious description of the timing summaries and their uncertainty, not a broad conclusion about preference or all aspects of the techniques.
16. Why This Trial Matters Statistically
This trial raises a statistical issue common to practical comparisons of procedures: the study design and the form of the reported analysis need to align. A crossover design can make within-participant comparisons possible because participants receive both approaches. In general, this can reduce the influence of stable differences between participants, but that benefit depends on analyzing the paired observations appropriately and accounting for sequence or other relevant design features.
The registry describes opposite-side use of DryShield and cotton rolls, with the side and order varying across groups. It also says the results were reported by sequence. Yet the posted comparisons are group-summary contrasts, and the registry record does not describe a paired model or adjustments for side and sequence. This makes it important to distinguish the design's potential for a paired comparison from the estimates actually reported. A reader should not assume that the posted contrasts use information from within-participant pairing when the analysis details are not reported.
The study also illustrates why effect estimates and intervals matter alongside p-values. The point estimates are close to zero, but the confidence intervals span values in both directions and remain broad. That combination does not establish equivalence; it means the posted comparisons leave uncertainty about the direction and size of the timing difference. Without a prespecified threshold for an important timing difference, statistical uncertainty cannot be translated into a judgment about practical importance.
Finally, the registry identifies patient preference as a goal but does not report preference findings. Statistical interpretation must remain tied to outcomes actually reported. The absence of posted preference results leaves that study question unanswered in the registry record, even though timing and adverse-event summaries are available.
17. Limitations
- The posted summary statistics are the only data these results rest on; patient-level data, full protocols and statistical analysis plans are not available.
- Recalculated results are simple, unadjusted calculations from posted summaries. They do not replace the sponsor's prespecified analysis.
Several limitations are specific to interpreting this registry entry. The enrollment is listed as 32, while each of the four timing group summaries lists 16 observations. Because participants received both techniques in a crossover arrangement, these group counts should not be treated as independent participant totals. The registry does not explain the relationship between the displayed counts and the participant-level paired data, or identify how many participants contributed a complete comparison.
The group descriptions indicate that treatment side and order varied, and the outcome description says results were reported according to sequence. However, the registry record does not report an analysis that accounts for side, order, within-participant correlation, or possible period effects. The published group summaries and unadjusted contrasts therefore cannot show whether such factors influenced the estimates.
The measurement is stopwatch-recorded by a dental assistant. The registry gives the timing start and end points, but does not report whether the assistant was masked to the technique, how timing consistency was assessed, or whether repeated measurements or checks were used. The study itself is listed as unmasked.
Participant characteristics, eligibility details, missing-data handling, analysis populations, protocol deviations, and follow-up details are not reported in the registry record. Patient-preference results are also absent despite being a stated study goal. The original sample-size justification and a formal analysis plan are not reported. These limitations constrain assessment of representativeness, precision, analysis choices, and the completeness of outcome reporting.
18. Related Tutorials
19. Related Statistical Calculators
20. Sources
- ClinicalTrials.gov: DryShield vs Cotton Roll Isolation During Sealants Placement: Efficiency and Patient Preference — NCT02995369.
- Registry record last updated 2023-01-20; status last verified 2022-11.
- Results first posted 2023-01-20.
- Data retrieved from ClinicalTrials.gov on 2026-11-09.
- Group sizes, means, event counts and sponsor-reported p-values are reproduced as posted. Effect estimates, confidence intervals and p-values not attributed to the sponsor are independently calculated from the posted summary statistics.
Continue through the Clinical Biostats statistical pathway
Use this trial's endpoint as a starting point for deeper study of effect measures, confidence intervals, and sample-size planning.
21. Record Summary
The registry describes a completed randomized, unmasked crossover study sponsored by Montefiore Medical Center, with enrollment of 32. It compared DryShield and cotton roll isolation during sealant placement. The primary endpoint was placement time in seconds, measured from insertion to removal of the corresponding isolation aid and recorded by a dental assistant with a stopwatch.
Four group summaries report mean times from 160.5 to 167.8 seconds. The three unadjusted mean differences relative to Cotton Roll Isolation (Left) have confidence intervals that include zero. The registry also lists patient preference as a study goal, but preference results are not reported in the registry record. Serious adverse events, other adverse events, and deaths are each listed as 0 for every group.