Effect of Miswak and Miswak Extract on Oral Malodor: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for Effect of Miswak and Miswak Extract on Oral Malodor (NCT02628938), a randomized phase 2 study. The primary outcome is Organoleptic Scores After the First Use of the Prescribed Method by 15 Minutes (Masking Effect), and After 7 Days of Use (Therapeutic Effect)..

2. Clinical Question

The design therefore sets up comparisons among a miswak stick, miswak extract mouthwash, and a chlorhexidine mouthwash. The comparison of the stick with the extract is relevant to the stated distinction between mechanical action and chemical effect. The chlorhexidine arm provides a separate active comparison. The registry record does not report a no-treatment or placebo group, and it does not give enough detail to assess how participants were assigned or what they were told about the interventions.

Volatile sulfur compound scores and self-assessment of mouth odor were listed as secondary outcomes. Those measures could provide complementary perspectives: a volatile-compound measure, a participant’s own assessment, and a judge’s rating of odor intensity. However, the record does not report results for these outcomes or explain how their findings were intended to be integrated with the primary outcome.

3. Trial Design

The trial is listed as randomized, single-masked, and parallel, with phase 2 status. Enrollment was 212. A parallel design assigns participants to an intervention group for the study rather than having every participant receive each intervention in sequence. Randomization is intended to make assigned groups comparable on average, although the registry record does not describe the allocation method, any stratification, or how the allocation sequence was concealed.

The listed interventions were miswak extract mouthwash, miswak sticks, and chlorohexidine gluconate mouthwash. The extract was described as a 50% aqueous solution, 5ml twice a day for 7 days. Miswak sticks were used twice a day for 7 days. The chlorhexidine mouthwash was described as a 0.2% aqueous solution, 5 ml twice a day for 7 days. The registry record does not describe adherence monitoring or whether participants could use other oral-care products during the trial.

Masking is recorded as single, but the record does not identify who was masked. That distinction matters because participants, outcome assessors, and analysts can each be masked or unmasked, and masking can affect subjective outcomes differently. The primary endpoint involved a judge’s assessment, but the registry does not state whether the judge was unaware of participants’ assigned interventions.

The trial started in 2014-03 and its primary completion was 2014-12. Its status is completed. These dates and the planned treatment duration do not establish how long participants were followed or whether all outcomes were collected at the planned times. Follow-up details beyond the stated endpoint timeframes are not reported in the registry record.

The registry describes a primary outcome at two timeframes: after the first use by 15 minutes and after 7 days of use. It also lists secondary outcomes for volatile sulfur compounds at those timeframes and self-assessment after 7 days. The posted record does not provide the results, participant flow, or group-specific numbers analyzed for these outcomes.

4. Participant Flow and Accounting

The registry reports how participants moved through each stage of the study. All counts below are exactly as posted; missing counts are not inferred from other stages.

Before assignment: 212 female students aged 18-35 were screened. 167 were excluded for not meeting the inclusion criteria. Only 45 were finally enrolled and distributed on the three groups

Overall Study

Reasons for not completing this period:

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 Organoleptic Scores After the First Use of the Prescribed Method by 15 Minutes (Masking Effect), and After 7 Days of Use (Therapeutic Effect)., measured over After the first use of the prescribed method by 15 minutes, and after 7 days of use.

The primary endpoint was the organoleptic score, a judge-rated assessment of odor intensity. The registry describes a calibrated judge who tested odor detection and discrimination using the Smell Identification Test. For the assessment, the participant closed their mouth for approximately 3 minutes while breathing through the nose, then slowly released air from the mouth. The judge assessed odor intensity from a distance of about 10 cm.

The rating scale ran from 0 to 5 units on a scale. A score of 0 meant no odor present; 1 meant barely noticeable odor; 2 meant slight but clearly noticeable odor; 3 meant moderate odor; 4 meant strong offensive odor; and 5 meant extremely foul odor. This ordered rating translates a sensory judgment into a score that can be compared across groups and timeframes, although it remains dependent on the assessor’s perception and the consistency of the assessment procedure.

The endpoint was measured after the first use by 15 minutes, described as a masking effect, and after 7 days of use, described as a therapeutic effect. These timeframes address different questions: an immediate change in odor rating and a rating after repeated use. They should not be treated as interchangeable. The registry record gives the endpoint definition but does not report group means, standard deviations, or comparisons at either timeframe.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

The registry describes the primary outcome as a mean continuous measure with standard deviation. This summary is commonly used when an outcome is numerical and the analysis focuses on average scores. The mean is the arithmetic average of observed scores. The standard deviation describes how far individual scores tend to lie from that average. Reporting both can help readers distinguish the group’s average level from the variability among participants. The registry record does not report either statistic for the primary endpoint.

What does the organoleptic score represent?

The score is based on a judge’s perception of odor intensity, recorded on an ordered scale from 0 to 5. Although the score is numerical, its categories have verbal descriptions, from no odor present to extremely foul odor. A mean score can be useful for comparing group averages, but it does not show how many participants fell into each category. Different distributions of individual scores can produce the same mean. The registry record does not report category counts or distributions.

The measure also depends on the consistency of the judge and the assessment conditions. The registry describes a calibrated judge and a standardized procedure involving mouth closure, breathing through the nose, slow release of air, and an assessment distance of about 10 cm. That description gives readers context for how the measure was obtained. It does not establish whether the same judge assessed all participants, whether more than one judge was involved, or whether the judge was masked to treatment assignment. Those details are not reported in the registry record.

Why distinguish the timeframes?

The primary outcome was assessed after the first use by 15 minutes and after 7 days of use. The first timeframe is described as a masking effect; the later timeframe is described as a therapeutic effect. An immediate assessment and an assessment after repeated use answer different questions, so each needs its own estimate and uncertainty. Repeated measurements on the same participant are also related rather than independent. General statistical methods can account for that relationship, but the registry record does not report which method was used or whether the analysis modeled within-participant correlation.

The registry’s sample-size assumptions specify a two-sided significance level of 0.05, equal allocation between two arms, and a normal approximation. In general, a two-sided test assesses evidence for a difference in either direction rather than prespecifying only an increase or only a decrease. Equal allocation means the planning illustration assumes the same number of participants in each of the two compared arms. These are assumptions for an illustration; the registry record does not report that they were the trial’s actual design assumptions or analysis plan.

What does a confidence interval add?

In general, a confidence interval expresses the uncertainty around an estimated effect. It helps readers judge which effect sizes are reasonably compatible with the data and the statistical model. It should be considered alongside the point estimate and the clinical meaning of the outcome. A p-value, when reported, addresses how compatible the observed data are with a specified null model; it does not measure the size or importance of an effect. Neither a confidence interval nor a p-value is reported for the primary outcome in the registry record.

For a continuous endpoint, an analysis may compare group means or model scores over time. The interpretation depends on the selected comparison, the participants included, and the assumptions used. The registry record does not report whether the primary analysis was adjusted for baseline score, whether it used an analysis of covariance or another model, or whether it accounted for repeated measures. Those methods cannot be inferred from the endpoint definition alone.

Why can dispersion and scale matter?

The standard deviation describes variation, but the organoleptic score is bounded by its defined scale. In general, a normal approximation is most useful when the statistical model reasonably represents the data. If observations are highly concentrated near the ends of a bounded scale, or if the category distribution is strongly uneven, a mean and standard deviation may not fully describe the pattern. Alternative summaries or models may be considered in such situations. The registry record does not report the observed score distribution, so there is no basis for judging whether a particular model was suitable.

Over-dispersion, in general, means that observed variability is greater than a model assumes. When it occurs, standard errors based on the narrower model can be too small, making uncertainty appear less than it is. This is a general consideration for statistical modeling, not a finding about this trial. The record does not provide the data needed to assess dispersion or the model diagnostics used.

The sample-size illustration is described as using the observed effect and as a planning illustration, with the effect to detect set as a stated fraction of that observed effect. It is not a report of observed power. Sample-size planning asks how many participants per arm would be needed under specified assumptions; it does not establish whether an estimated result is reliable or clinically important. The primary outcome’s multiple timeframes and the record’s omission of a single reduced comparison also limit how directly such an illustration can be tied to an overall primary conclusion.

10. Multiplicity, Missing Data and Analysis Populations

The primary outcome has multiple time points, and the registry notes that it was not reduced to a single comparison. The record also lists secondary outcomes and 15 analyses. When several outcomes, time points, or group comparisons are examined, the chance of finding an apparently notable result by chance can increase if each analysis is interpreted separately. General approaches include specifying a primary comparison in advance, adjusting for multiple testing, or treating secondary analyses as exploratory. The registry record does not report whether any such approach was planned or used.

Missing-data methods are also not described. The record does not report how many participants completed each assessment, whether any scores were missing, why data might be absent, or whether an imputation or other missing-data method was used. Without those details, the extent to which the analyzed participants represent the randomized groups cannot be evaluated.

The analysis populations are not reported in the registry record. It is therefore not possible to tell whether the primary analysis included all randomized participants, only participants who completed treatment, or another defined population. The record also does not describe adherence, protocol deviations, exclusions after randomization, or how such events were handled statistically.

The listed sample-size illustration assumes equal allocation between two arms. The trial lists multiple interventions, but the record does not report which pairwise comparison or comparisons underlie each planning calculation. The trial’s own sample-size justification and any adjustments for multiple comparisons are not reported in the registry record. These omissions leave uncertainty about how the analysis strategy related to the trial’s design and intended claims.

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

The registry record establishes that a randomized, single-masked, parallel phase 2 trial was conducted with enrollment of 212 and that it assessed organoleptic scores after the first use by 15 minutes and after 7 days. It also identifies the interventions and the stated rationale for comparing miswak sticks with miswak extract. These design details describe what was studied, not what the outcomes showed.

The primary outcome results are not reported in the registry record. No group means, standard deviations, effect estimates, confidence intervals, or p-values are given. It is therefore not possible to determine from this record whether scores differed between groups, whether any difference was larger at one timeframe than another, or how precise any estimate might have been. The same limitation applies to the listed secondary outcomes.

Even if an outcome comparison were reported, a statistical difference would not by itself explain the practical importance of that difference. Interpretation would depend on the size and uncertainty of the estimate, how the scale is understood, the participant population, and the analysis methods. Conversely, a non-significant test would not establish that interventions were equivalent. Equivalence requires an appropriate design and a prespecified margin, neither of which is reported in the registry record.

The registry lists zero participants at risk and zero affected participants for serious and other adverse events in each intervention group. These entries do not provide meaningful denominators for assessing safety, and deaths are recorded as null. They should not be read as evidence that no adverse events occurred among participants; the safety information is not sufficiently reported in the registry record to support that conclusion.

The record is consequently informative about the research question and planned measurements, but not about the estimated effects. Any conclusion about comparative changes in oral malodor would require results and analysis details that are not reported in the registry record. The study design alone cannot establish whether an intervention produced a particular outcome.

12. Why This Trial Matters Statistically

This trial poses a useful statistical question because its stated aim separates the mechanical action of a miswak stick from the chemical effect of a miswak extract. A randomized comparison can, in principle, help distinguish those explanations when the interventions and analyses are clearly specified and the results are reported. The registry record identifies the relevant intervention groups, but does not report their outcome estimates or the comparisons used for inference.

The primary endpoint also illustrates the challenges of turning a sensory judgment into a quantitative outcome. The organoleptic scale has defined verbal categories and a described assessment procedure, yet its scores remain dependent on an assessor’s perception. Statistical summaries need to be interpreted with that measurement process in mind. Information about assessor masking, score distributions, and consistency of ratings would help readers assess the reliability of group comparisons; those details are not reported in the registry record.

Assessments after the first use and after 7 days address different timeframes. This makes the analysis more complex than a single endpoint at a single time, because each estimate needs a clear interpretation and the relationship between repeated observations may matter. The registry lists multiple analyses and secondary outcomes, but does not report a multiplicity strategy or a primary comparison that reduces the results to a single contrast.

The record also highlights the difference between trial planning and trial findings. A sample-size illustration based on an observed effect can help illustrate planning under stated assumptions, but it is not observed power and cannot substitute for estimates with uncertainty. Because results are not reported in the registry record, the statistical value of the design cannot be evaluated from outcomes alone.

13. 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 details needed to assess the trial’s conduct and generalizability are not reported in the registry record. Participant eligibility criteria, recruitment details, and baseline characteristics are absent from the available description. Without them, readers cannot determine how closely the enrolled participants represent a particular clinical population or whether the intervention groups were similar at baseline.

The record identifies the trial as single-masked but does not say who was masked. This is especially relevant for an assessor-rated odor outcome: the procedure names a judge, but the judge’s awareness of assigned intervention is not reported. Allocation concealment and the method used to generate the random sequence are also not reported, so the safeguards against selection bias cannot be assessed.

The record does not provide participant flow, group-specific numbers analyzed, adherence information, protocol deviations, or reasons for missing outcome data. It does not describe the primary analysis model, any adjustment for baseline scores, or whether repeated measurements were handled jointly. The trial’s sample-size justification and its plan for multiple outcomes or comparisons are also not reported in the registry record.

Most importantly, the record does not report the primary or secondary outcome results. The adverse-event entries list zero participants at risk and zero affected participants in each group, while death values are null. Those entries do not establish that no adverse events occurred, because the denominators and fuller safety reporting are unavailable. These limits prevent assessment of the observed effects, their precision, and the completeness of the safety record.

14. Related Tutorials

15. Related Statistical Calculators

16. Sources

• ClinicalTrials.gov: Effect of Miswak and Miswak Extract on Oral Malodor — NCT02628938.
• Registry record last updated 2016-05-11; status last verified 2016-04.
• Results first posted 2016-05-11.
• 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.

17. Record Summary

NCT02628938, Effect of Miswak and Miswak Extract on Oral Malodor, is listed as a randomized, single-masked, parallel phase 2 trial with enrollment of 212. The registry lists miswak extract mouthwash, miswak sticks, and chlorohexidine gluconate mouthwash. Treatment instructions specify use twice a day for 7 days.

The primary outcome was a judge-rated organoleptic score assessed after the first use by 15 minutes and after 7 days. Secondary outcomes were volatile sulfur compound scores at those timeframes and self-assessment of mouth odor after 7 days. The trial status is completed, with start in 2014-03 and primary completion in 2014-12.

The registry record does not report the outcome estimates, statistical comparisons, missing-data methods, analysis populations, or sample-size justification. The listed adverse-event entries have zero participants at risk and zero affected participants in each group; deaths are recorded as null. These entries do not support a conclusion that adverse events were absent.