Reducing Aerosol and Bioaerosol Using Different Oral Suctions: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for Reducing Aerosol and Bioaerosol Using Different Oral Suctions (NCT05848245), a randomized na study. The primary outcome is Particulate Matter (PM).

2. Clinical Question

The clinical context is aerosol and bioaerosol generated during dental procedures. The study summary says particles, oral bacteria, fungi, and microbial air were to be assessed. However, the posted primary outcome is particulate matter, and the registry record does not report results for the microbial outcomes. The central statistical question is therefore narrower than the study's full stated aim: whether observed particulate matter means differed across the suction groups, especially relative to low suction.

3. Trial Design

The registry record describes a completed randomized, parallel-group clinical trial with no masking. It lists enrollment as 50 and reports five groups: low suction, intraoral suction, high and low suction, extra-oral suction and low suction, and extra-oral suction with intraoral suction. Each group has 10 participants in the posted outcome summaries. The listed study start was 2023-05-01, and primary completion was 2023-09-01.

The brief study summary describes recruitment at an educational hospital, a public hospital, and a private clinic, and says 40 subjects would be recruited in each place. That description does not align with the registry's enrollment of 50; the record does not explain the difference. The summary also describes four intervention groups, while the posted results identify five arms including low suction. The group labels in the posted outcome summaries are used for the comparisons.

The trial compared suction-device configurations during scaling and prophylaxis. The summary describes particle and microorganism measurements before the procedure and during it, including particle count and microbial measures. The primary outcome record instead gives a particulate matter endpoint with a timeframe of 2 months. How that timeframe relates to the measurement schedule in the summary is not reported in the registry record.

The registry identifies the trial phase as not applicable. Details of sequence generation, allocation concealment, site-specific assignments, and the original sample-size justification are not reported in the registry record. The record names two outcome measures but posts no secondary outcome results.

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

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 Particulate Matter (PM), measured over 2 months.

The primary endpoint is particulate matter (PM), expressed as a mean in micrograms per cubic meter (µg/m³), with standard deviation as the reported measure of spread. The outcome description says PM was measured with a digital dust monitor using light scattering. The device is described as measuring particles from 0.1 to 10 µm, with a flow rate of 1 L/min and a built-in filter intended to eliminate coarse particles.

PM provides a quantitative measure of particles in the clinic air. It is relevant to the study's stated concern about airborne material generated during dental procedures, but it is not itself a measure of infection, bacterial concentration, fungal concentration, or a clinical health outcome. The registry record does not report the values for those other outcomes.

As a continuous outcome, PM can be summarized by a group mean and standard deviation and compared between groups. The mean describes the average measurement in a group, while the standard deviation describes how spread out measurements were around that mean. Those summaries do not show the full distribution or how measurements changed over time. The registry gives a timeframe of 2 months for the primary outcome, but the precise timing and aggregation of PM measurements are not reported in the registry record.

7. Results Posted in the Registry

• Intraoral Suction: mean 135.10 versus 121.30 on control; difference 13.80 (95% CI -8.56 to 36.16), standardized effect d = 0.54; z-test p = 0.226.
• High & Low Suction: mean 147.60 versus 121.30 on control; difference 26.30 (95% CI 6.02 to 46.58), standardized effect d = 1.14; z-test p = 0.011.
• Extra-oral Suction & Low Suction: mean 128.40 versus 121.30 on control; difference 7.10 (95% CI -8.78 to 22.98), standardized effect d = 0.39; z-test p = 0.381.
• Extra-oral Suction and Intraoral Suction: mean 136.90 versus 121.30 on control; difference 15.60 (95% CI -4.51 to 35.71), standardized effect d = 0.68; z-test p = 0.128.

8. Statistical Interpretation

9. Statistical Methods Explained

What is being compared? The primary outcome is a continuous measurement, and the registry reports a mean and standard deviation for each suction group. The pairwise estimates compare each of four groups with low suction. A mean difference is expressed in the same units as the outcome, so each estimate describes the difference in average PM concentration rather than a standardized score.

General statistical context: comparing means can be useful when the outcome is quantitative, but the mean alone does not describe every feature of the data. The standard deviation gives a sense of the observed spread around the mean. A relatively large standard deviation compared with a mean difference can signal that individual measurements vary considerably, making a group contrast less precisely estimated. The posted group summaries allow readers to see that spread, but they do not provide the raw observations or reveal whether distributions were skewed, had outliers, or differed across sites.

How should the mean differences be read?

The reference mean is 121.3 µg/m³ in the low-suction group. Each estimate subtracts that reference mean from the mean in one other group. For example, the estimate for high and low suction is 26.3 µg/m³, matching the posted means of 147.6 and 121.3. The other estimates are 13.8, 7.1, and 15.6 µg/m³ for intraoral suction, extra-oral suction and low suction, and extra-oral suction with intraoral suction, respectively. These estimates are unadjusted and reflect only the posted group summaries.

A confidence interval expresses uncertainty around an estimate under the assumptions of the calculation. General statistical context: if an interval includes zero, the data do not rule out a zero mean difference at the corresponding confidence level, while also allowing other differences within the interval. If it excludes zero, that is evidence of a nonzero contrast under the calculation's assumptions. An interval is not a range that contains a fixed proportion of individual measurements, and it does not account automatically for selection of comparisons or other sources of bias.

What does a p-value contribute?

The reported p-values for the recalculated comparisons are 0.226, 0.011, 0.381, and 0.128. General statistical context: a p-value describes how compatible the observed data are with a specified null model of no mean difference, assuming the model and calculation are appropriate. It is not the probability that the null hypothesis is true, nor does it measure the size or practical importance of a difference. The confidence interval supplies a range of estimates and is often more informative about magnitude and precision than a threshold-only reading of a p-value.

The study summary says differences among groups and measurements were to be tested with a two-way ANOVA or one-way ANOVA. ANOVA is a general method for assessing mean differences across groups. A one-way approach considers one grouping factor; a two-way approach can consider two factors and, depending on specification, their interaction. The registry record does not report which ANOVA model was used, what factors entered it, how repeated measurements were handled, or whether covariates were included. It therefore cannot be assumed that the recalculated pairwise estimates reproduce a final ANOVA model.

Why can unequal spread matter?

General statistical context: many mean-comparison procedures rely on assumptions about the distribution of errors and, for some versions of ANOVA, similar variances across groups. If variability differs markedly, a conventional pooled-variance procedure may yield confidence intervals or p-values with less reliable coverage. Unequal group variances can be addressed with alternative methods, but the registry record does not say whether assumptions were checked or whether a variance-robust method was used. The group standard deviations vary, and the registry does not include participant-level measurements needed to assess the pattern in detail.

General statistical context: over-dispersion matters most directly for outcomes modeled as counts or rates when observed variability exceeds what the assumed model allows. The primary PM endpoint is reported as a continuous mean, not as a count outcome, so a count-model interpretation should not be imposed. Particle count and microbial measures are mentioned in the study summary, but their outcome definitions and posted results are absent; whether over-dispersion is relevant to those measures cannot be determined from the registry record.

What can the intended analysis tell readers?

The summary's reference to ANOVA indicates an intended comparison of group measurements, but does not provide enough detail to reconstruct the analysis. In particular, the record does not report whether the procedure-level timing created repeated measurements, whether site was included in the model, or how correlations among measurements from the same participant were handled. These design features can affect standard errors and inference. Since the posted comparisons are recalculated from summary statistics, they should be treated as simple unadjusted comparisons rather than as proof of the originally intended model's results.

10. Confidence Intervals and Precision

Precision is reflected by the width of a confidence interval: narrower intervals indicate a more precise estimate, while wider intervals leave more uncertainty about the size and direction of the difference. The recalculated interval for intraoral suction extends from -8.557 to 36.16 µg/m³. For high and low suction it extends from 6.018 to 46.58. For extra-oral suction and low suction it extends from -8.775 to 22.98, and for extra-oral suction with intraoral suction it extends from -4.51 to 35.71.

Three intervals include zero, allowing both a zero difference and differences in either direction within the stated ranges. The interval for high and low suction is entirely above zero. That interval still allows a range of possible positive differences, rather than pinpointing a single true value. Its associated unadjusted p-value is 0.011, but neither the interval nor the p-value accounts for multiplicity across the several comparisons.

The posted group summaries have 10 participants in each arm. Precision is limited by the uncertainty around estimates, which is visible in the intervals, and by the absence of participant-level data and details of the final analysis model. The confidence intervals are recalculated unadjusted intervals, not sponsor-reported intervals. They describe sampling uncertainty under the calculation's assumptions, not uncertainty due to measurement error, differences between clinics, missing data, or possible bias. Those issues are not quantified in the registry record.

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.

The sample-size calculations are planning illustrations based on each observed mean difference, not the trial's original design calculation. For these continuous outcomes, the figures are participants per arm, not total events. The stated assumptions are a two-sided significance level of 0.05, equal allocation between the two arms, a normal approximation, and an effect to detect set at the stated fraction of the observed effect. The original trial's sample-size assumptions and justification are not reported in the registry record.

The 80% power column describes the number of participants per arm estimated to give an 80% chance of detecting the specified effect under those assumptions, if that effect is present and the model assumptions hold. The 90% power column gives the corresponding planning target for a 90% chance. These are design probabilities for hypothetical future studies, not guarantees that a study of that size will produce a particular finding.

The scenarios use 100%, 75%, or 50% of the observed effect. For example, using 100% of the observed effect, the high-and-low-suction comparison gives 13 participants per arm for 80% power and 17 participants per arm for 90% power. Using 50% of that observed effect gives 49 participants per arm for 80% power and 66 participants per arm for 90% power. A smaller target effect requires more participants because it is harder to distinguish from random variation.

For the intraoral-suction comparison, the corresponding planning figures are 54 participants per arm for 80% power and 72 participants per arm for 90% power when planning for 100% of the observed effect. The figures are especially sensitive to the assumed effect: the observed difference may not be a stable estimate of the effect a future study should target. This is not observed power; it is a set of conditional planning illustrations based on the observed estimates.

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 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 = 13.800; pooled standard deviation σ = 25.507.
2. n = 2 × (1.96 + 0.842)² × 25.507² / 13.800² = 53.6, rounded up to 54 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 <- 13.8                      # observed difference in means
sigma <- 25.5068618218706                     # 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(5848245)
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 = 54 (80% power), 72 (90% power)
 75% of observed effect: n per arm = 96 (80% power), 128 (90% power)
 50% of observed effect: n per arm = 215 (80% power), 288 (90% power)
power.t.test: 54.6 
Simulated power at n = 54 per arm: 0.794 (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 posted comparisons include four contrasts against low suction. When several outcomes or contrasts are examined, the chance of at least one apparently unusual result can increase if each is interpreted without accounting for the full set of tests. General statistical context: multiplicity procedures can control error rates across a family of comparisons, but the method and the family of tests must be specified to interpret adjusted inference.

The registry record does not report a multiplicity adjustment or identify a prespecified family of comparisons. The p-values and confidence intervals described for the pairwise contrasts are recalculated and unadjusted. The p-value of 0.011 for high and low suction should therefore be read as an unadjusted result, not as evidence that the trial's planned multiplicity procedure was satisfied. No such procedure is reported.

The record names two outcome measures, but only the particulate matter outcome has posted results in the material available in the registry record. The study summary also mentions particle count, oral bacteria, fungus, and microbial air, but does not provide results for these measures. Which outcome was designated as primary in the original analysis plan, how secondary outcomes were handled, and whether there were additional exploratory outcomes are not reported in the registry record.

Missing-data handling is not reported in the registry record. It does not state whether all randomized participants contributed to the PM summaries, how missing measurements were treated, whether any observations were excluded, or whether an intention-to-treat population was used. The analysis population and any per-protocol definition are also not reported. These omissions matter because missingness or exclusion can affect group comparability and the interpretation of the observed means.

The brief summary names one-way ANOVA or two-way ANOVA as planned methods, but the registry record does not identify the final model, its factors, adjustment variables, or diagnostics. It also does not report interim analyses or stopping rules. The available recalculated contrasts cannot fill those gaps or establish which methods the investigators ultimately used.

14. Safety Results

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

Deaths

Other (non-serious) adverse events

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

The registry lists serious adverse events, other adverse events, and deaths by suction group. For every reported group, the number at risk is 10 for serious and other adverse events, and the number affected is 0 in both categories. The registry also reports 0 deaths in every group.

These entries mean that no affected participants or deaths are recorded in the adverse-event fields for the groups as reported. They do not establish that no unrecorded events occurred, and they do not quantify uncertainty about uncommon events. The record does not provide event terms or additional detail; no serious-event terms are listed. Follow-up duration and the method used to collect adverse events are not reported in the registry record.

Safety entries should be interpreted separately from the PM comparisons. The adverse-event information does not show whether measured air particles changed, and the PM results do not establish safety. These registry entries describe reported events in this trial record; they are not medical advice or a complete safety assessment.

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

The posted results describe mean PM measurements across five suction groups. The low-suction mean was 121.3 µg/m³, while the other group means ranged from 128.4 to 147.6 µg/m³. Recalculated comparisons estimated positive mean differences versus low suction in all four contrasts. The intervals for intraoral suction, extra-oral suction and low suction, and extra-oral suction with intraoral suction include zero; the interval for high and low suction does not.

Those observations answer a limited statistical question about measured particulate matter. They do not establish that a particular device configuration reduces aerosol exposure, prevents infection, or improves health. In the reported comparisons, the differences are expressed in PM concentration, and the trial record does not provide a threshold for a clinically meaningful difference. The microbial measures mentioned in the study summary have no posted results in the registry record.

The recalculated estimates are unadjusted. The registry record does not report the final analysis model, multiplicity handling, missing-data approach, or site-specific results. The group means and intervals therefore should not be treated as a complete account of all planned analyses. The available information also does not show whether measurements were aggregated across time points or how the stated 2-month endpoint timeframe relates to the procedure measurements described in the summary.

In general, statistical evidence and practical importance are distinct. A p-value describes compatibility with a statistical null model under assumptions; it does not reveal whether a difference matters clinically or operationally. Confidence intervals show the range of values compatible with the calculation, but they do not eliminate uncertainty related to bias, measurement, or generalizability. These results are best understood as an initial, limited description of PM in this trial's reported groups, not as a definitive comparison of the devices for all dental settings.

16. Why This Trial Matters Statistically

This trial raises statistical questions that are common in clinical and environmental measurement studies. A continuous outcome such as particulate matter can be summarized with means and standard deviations, but interpretation depends on both the size of group differences and the variability of measurements. The reported standard deviations are sizable relative to some of the estimated contrasts, and the confidence intervals show that several comparisons remain imprecise.

Multiple groups also create an inference challenge. Four comparisons against low suction are reported, alongside a study summary that describes several possible measurements. Without a reported multiplicity strategy, a single unadjusted p-value should not be treated as a complete answer to a broad study aim. Prespecified outcomes and analysis methods help distinguish confirmatory questions from exploratory comparisons; those details are not reported in the registry record.

The design description also highlights the importance of reconciling protocol-level statements with posted data. The summary refers to recruitment at three locations and 40 subjects in each, whereas the registry lists enrollment of 50 and provides five groups with 10 participants each. The record does not explain the difference. This limits what can be inferred about site representation and the route from intended recruitment to analyzed data.

Finally, the study's motivation includes particulate matter and microbial air, yet the posted primary results are limited to PM summaries. That separation matters: one measured exposure cannot stand in for other outcomes. Complete reporting of endpoints, analysis populations, missingness, multiplicity, and site-level findings would allow a fuller assessment of both statistical precision and relevance to dental-clinic conditions.

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.

The posted group summaries are based on 10 participants per arm, and several recalculated intervals are wide. The registry does not include raw measurements, so the distributions, outliers, repeated observations, and within-person correlations cannot be assessed. The reported comparison estimates are unadjusted, and the final analysis model is not reported.

Masking is listed as none. The record does not describe whether outcome measurement or data processing was blinded, how randomization was generated, or whether allocation was concealed. These details are important for understanding potential sources of bias. Site-specific results are not reported, although the study summary names three clinical settings.

The study summary's recruitment statement of 40 subjects in each location differs from the registry enrollment of 50. The record does not explain whether this reflects a change in the study, a summary error, or a difference between planned and actual enrollment. It also reports five outcome arms, while the summary describes four intervention groups; the relationship between those descriptions is not clarified.

The primary outcome timeframe is given as 2 months, while the summary describes measurements before and during scaling and prophylaxis. How these timings correspond is not reported. The record does not report missing-data handling, participant flow by analysis population, multiplicity procedures, or the original sample-size rationale. Results for the microbial outcomes described in the summary are absent. These limitations constrain interpretation to the posted PM group summaries and the unadjusted recalculations.

18. Related Tutorials

19. Related Statistical Calculators

20. Sources

• ClinicalTrials.gov: Reducing Aerosol and Bioaerosol Using Different Oral Suctions — NCT05848245.
• Registry record last updated 2025-04-16; status last verified 2025-04.
• Results first posted 2025-04-16.
• 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.

21. Record Summary

NCT05848245 is a completed randomized, parallel-group dental clinical trial with no masking. The registry lists enrollment of 50 and five reported suction groups, with 10 participants in each posted PM summary. The primary endpoint is mean particulate matter in µg/m³, measured with a digital dust monitor; the listed timeframe is 2 months.

Posted group means range from 121.3 in the low-suction group to 147.6 in the high-and-low-suction group. Recalculated unadjusted comparisons against low suction show a confidence interval excluding zero for high and low suction, while the other three intervals include zero. The study summary mentions microbial outcomes, but the registry record does not post their results or detail the final analysis plan.