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 The Effect of Silver Diamine Fluoride (SDF) on Bacteria Involved in Root or Cervical Carious Lesions (NCT02953886), a na phase 4 study. The primary outcome is Change in Bacterial Composition Before and One Month After SDF Application to Root or Cervical Caries Lesions.
| Feature | Registry value |
|---|---|
| ClinicalTrials.gov identifier | NCT02953886 |
| Phase | Phase 4 |
| Condition | Caries |
| Allocation | Not applicable (single group) |
| Design model | Single Group |
| Masking | None (open label) |
| Enrollment | 21 |
| Arms in the primary outcome | n/a |
| Lead sponsor | Heba Mitwalli |
| Results posted | Yes |
2. Clinical Question
Population
The study concerns people with root or cervical carious lesions. The registry lists caries as the condition and records enrollment of 21 participants. It does not further describe participant characteristics, eligibility details, or the number of lesions sampled per participant.
Intervention
The intervention was application of silver diamine fluoride (SDF) to root or cervical carious lesions. Plaque was collected before treatment and one month after application. The registry identifies the intervention as a device and describes bacterial identification using HOMINGS technology.
Comparator
There was no separate control group in the registered design. Each participant’s bacterial composition was assessed at baseline and again one month after SDF application. This is a within-group before-and-after comparison, not a randomized comparison of SDF with an untreated group or another treatment.
Primary question
The primary question was whether the number of bacteria, as used to describe total bacterial composition, changed between baseline and one month after SDF application. The registry describes measuring the difference in bacterial count using HOMINGS. It does not report the observed change, its direction, or its uncertainty.
3. Trial Design
The registry describes a completed, phase 4, single-group clinical study, with enrollment of 21. The listed study dates begin in 2016-11, and the primary completion date is 2017-04-20. The listed status is completed. The intervention was silver diamine fluoride (SDF), applied to root or cervical carious lesions. Plaque collection was planned before treatment and one month after application.
Because the study uses a single group, each participant’s baseline measurement serves as the reference for the later measurement. There is no separately assigned control arm, and the registry lists allocation as not applicable and masking as none. The design therefore evaluates change over time in the treated group; it does not provide a concurrent estimate of what would have happened over the same period without SDF.
The primary outcome is described as change in bacterial composition, expressed as a bacterial count and measured using HOMINGS, or human oral microbiome identification using next-generation sequencing. A secondary outcome concerns patients’ assessment of the treated tooth’s appearance, including concern about appearance and desire for the tooth to be filled. The record lists three outcome measures but does not provide numerical outcome results or describe the additional measures in detail.
The registry record does not report a protocol-level statistical analysis plan, sample-size justification, interim analyses, or details of the sampling and laboratory procedures beyond the HOMINGS description. These omissions limit how fully the planned analysis and measurement process can be reconstructed.
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 | Silver Diamine Fluoride (SDF) |
|---|---|
| STARTED | 20 |
| COMPLETED | 20 |
| NOT COMPLETED | 0 |
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 | Silver Diamine Fluoride (SDF) |
|---|---|---|
| Participants analysed | 20 | |
| Age, Categorical: <=18 years | Participants | 0 |
| Age, Categorical: Between 18 and 65 years | Participants | 13 |
| Age, Categorical: >=65 years | Participants | 7 |
| Sex: Female, Male: Female | Participants | 8 |
| Sex: Female, Male: Male | Participants | 12 |
| Race (NIH/OMB): American Indian or Alaska Native | Participants | 0 |
| Race (NIH/OMB): Asian | Participants | 0 |
| Race (NIH/OMB): Native Hawaiian or Other Pacific Islander | Participants | 0 |
| Race (NIH/OMB): Black or African American | Participants | 3 |
| Race (NIH/OMB): White | Participants | 16 |
| Race (NIH/OMB): More than one race | Participants | 0 |
| Race (NIH/OMB): Unknown or Not Reported | Participants | 1 |
| Region of Enrollment: United States | Participants | 20 |
6. Primary Endpoint
The registry lists the primary outcome as Change in Bacterial Composition Before and One Month After SDF Application to Root or Cervical Caries Lesions, measured over baseline, One month after SDF.
| Element | Registry entry |
|---|---|
| Result type | Number |
| Measure of spread | not applicable |
| Unit | bacterial count |
| Endpoint classification | not reduced to a single comparison |
The primary endpoint concerns change in the bacterial composition of root or cervical carious lesions between baseline and one month after SDF application. The registry describes the measurement as a difference in bacterial count, using HOMINGS to identify bacteria through next-generation sequencing. It characterizes the outcome as the total bacterial composition of all subjects.
A before-and-after bacterial measure can describe whether the measured microbial profile differs over the specified follow-up period. This may be useful for studying a biological response to treatment, because the same participant is measured at both time points. Pairing observations can account for stable differences between participants when the analysis is designed to use that pairing.
The registry does not explain exactly how bacterial identifications are converted into the stated count, how results are combined across bacteria or participants, or how the difference is signed. It does not state whether the primary summary is a raw count, a transformed measure, or another derived quantity. The observed baseline and follow-up values, the estimated change, and its precision are not reported in the registry record. Without those details, the endpoint’s numerical meaning and the size and direction of any change cannot be assessed.
7. Why No Re-analysis Is Shown
8. Statistical Interpretation
The registry record identifies a relevant within-group question: whether bacterial composition in sampled lesions differs between baseline and one month after SDF application. It also gives the study’s basic design and the intended measurement approach. However, it does not report the numerical results for the primary endpoint. There is therefore no posted estimate of bacterial-count change to interpret, and no reported uncertainty interval or test result that would indicate how precisely a change was estimated.
The study is single-group and unmasked. A baseline-to-follow-up difference, if reported, would describe change among the treated participants during the observation period. On its own, that difference would not isolate the effect of SDF from other possible explanations, such as changes over time, differences in plaque sampling, or measurement variability. These are general considerations for before-and-after studies, not claims about what occurred in this study.
The endpoint is described as the difference in bacterial count from baseline to one month after treatment, but the registry does not specify the direction convention or the aggregation method. As a result, even a reported signed value would require a clear definition of how the difference was calculated to establish whether a positive or negative value represents a higher count at follow-up. No such numerical value is present in the registry record.
The record lists 21 participants and identifies an appearance-related secondary outcome, but numerical findings for that outcome are not reported in the registry record. It also lists three outcome measures without presenting their results. The absence of registered analyses means there is no reported analysis description to clarify how repeated observations, bacterial counts, or multiple outcomes were handled.
For these reasons, the available record supports a description of the research question and design, but not a quantitative conclusion about the observed bacterial change. It also does not allow assessment of the precision of an estimated change or of how well the findings might apply beyond the study participants. A biological measurement can be informative without establishing a clinical benefit; the registry record does not provide evidence sufficient to make that separate judgment.
9. Statistical Methods Explained
What does a before-and-after comparison estimate?
In a within-group design, measurements taken from the same participants at baseline and follow-up can be compared as paired observations. The analysis may focus on each participant’s change rather than treating baseline and follow-up observations as unrelated. Pairing can be useful because stable characteristics shared by a participant’s measurements may contribute less to the estimated change. This is a general statistical feature of repeated measurements, not a statement about the analysis used in this study.
The registry describes measuring bacterial composition at baseline and one month after SDF. It does not state whether the analysis used participant-level paired differences, pooled bacterial counts, or another approach. It also does not describe whether all participants had usable measurements at both time points. The exact estimand—the quantity the analysis aims to estimate—is therefore not fully specified in the registry record.
What does a count outcome require?
Count outcomes record numbers of events or items, rather than measurements on a continuous scale. Their distribution can depend on the typical count, variation among observations, and the frequency of small or zero counts. A count analysis may need methods that reflect these properties. The registry calls the primary outcome a bacterial count but does not report its distribution, the scale used for analysis, or the statistical model.
Over-dispersion is a general concern for count data. It occurs when the variation in the observed counts is greater than a simple model would expect. If it is present but not addressed, estimated uncertainty can be too small. The registry does not report whether over-dispersion was assessed or how it was handled. This is an explanation of a general issue, not an assertion that over-dispersion occurred in this study.
How should an estimated change and its uncertainty be read?
An estimated change describes the direction and magnitude of the difference under the analysis definition. A confidence interval, when reported, gives a range of values compatible with the data and the assumptions of the statistical method at the stated confidence level. A narrow interval indicates greater precision than a wide interval, although precision alone does not establish clinical importance. The registry does not report an estimate or confidence interval for the primary endpoint, so neither direction nor precision can be assessed.
A significance test, if used, would address compatibility with a specified null hypothesis under the test’s assumptions. A p-value would not measure the size of an effect, the probability that the null hypothesis is true, or the probability that a result will repeat. No primary-outcome test result or analysis method is reported in the registry record. The record lists no registered analyses, so the analysis approach cannot be checked against a stated plan.
What do the planning assumptions mean?
The record describes planning illustrations based on an observed effect, with a two-sided significance level of 0.05, equal allocation between two arms, and a normal approximation. It says the effect to detect is a stated fraction of the observed effect. These are planning assumptions, not a description of the registered single-group study design. The study itself is not a randomized two-arm comparison.
Such illustrations are hypothetical sample-size calculations. They do not represent the number of participants actually analyzed, and they are not observed power. The registry record does not report the numerical primary outcome effect needed to assess the basis for those illustrations. Without a reported effect and its uncertainty, the assumptions cannot be evaluated as a guide to interpreting the study’s results.
Why does the design matter for interpretation?
A single-group before-and-after design can document temporal change but does not include a concurrent untreated comparison. General influences on measurements over time cannot be separated from treatment-associated change using that comparison alone. Masking is listed as none, which means the record does not describe blinded assessment. The possible importance of this depends on how samples were collected, processed, and analyzed; those procedural details are not reported in the registry record.
HOMINGS is identified as the technology used to assess bacterial composition, but the registry does not provide further details about quality control, laboratory reproducibility, or how the microbial findings were summarized. Those details matter because choices in measurement and data processing can affect count outcomes. No assumptions beyond the stated registry description can be made about those procedures.
10. Multiplicity, Missing Data and Analysis Populations
The registry lists three outcome measures, including the primary bacterial-composition outcome and a secondary patient assessment of the treated tooth’s appearance. It does not report numerical results for these outcomes or describe whether additional comparisons were planned. When several outcomes or tests are examined, the chance of at least one apparently unusual result can increase. Statistical approaches can address multiplicity, but the registry record does not report whether any adjustment or prioritization beyond identifying a primary outcome was specified.
The record lists no registered analyses. It does not report a prespecified analysis plan, the handling of repeated measurements, or how the primary endpoint was to be summarized. It also does not state whether analyses were exploratory or confirmatory. Consequently, readers cannot compare reported analyses with a registered plan or determine whether analytic choices were made before results were examined.
Missing-data handling is not reported in the registry record. There is no description of missing samples, incomplete follow-up, exclusions from analysis, imputation, or sensitivity analyses. The enrollment figure does not establish how many participants contributed usable measurements at both time points. The analysis population is also not described. These gaps prevent assessment of whether the primary comparison included all enrolled participants or a subset, and whether missing observations could have affected the interpretation.
11. 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 |
|---|---|---|---|
| Silver Diamine Fluoride (SDF) | 0 | 21 | 0.0% |
Deaths
| Arm | Deaths (participants affected of at risk) |
|---|---|
| Silver Diamine Fluoride (SDF) | 0 of 21 |
Other (non-serious) adverse events
Participants with at least one non-serious event at or above the registry's 5% reporting threshold.
| Arm | Participants affected of at risk |
|---|---|
| Silver Diamine Fluoride (SDF) | 21 of 21 |
Most frequent non-serious adverse event terms
| Event term | Organ system | Silver Diamine Fluoride (SDF) |
|---|---|---|
| Black stain | General disorders | 21 of 21 |
| Unfavorable taste | General disorders | 3 of 21 |
| Burning sensation | General disorders | 1 of 21 |
The registry records zero participants with a serious adverse event among 21 at risk in the SDF group. It lists 21 at risk and 21 affected for other adverse events, with zero deaths. The record does not provide serious adverse-event terms or further details about the other adverse events, their definitions, severity, timing, or relationship to SDF.
The zero serious adverse events entry means that none were recorded in the registry’s stated group and category. It does not establish that serious events are impossible or that the intervention is free of risk. The other-adverse-event entry should not be interpreted as meaning that all participants experienced the same event: the registry does not specify which events were included or how the affected count was determined. These entries describe the registry’s safety reporting, not a complete account of every possible safety outcome.
The record does not describe how adverse events were solicited, monitored, or classified, nor does it provide a comparison group. Safety findings therefore cannot be compared with an untreated group from this design. The absence of event details limits interpretation of the broad other-adverse-event count.
12. What the Result Does, and Does Not, Mean
The study was designed to examine bacterial composition in root or cervical carious lesions before and one month after SDF application. Its single-group structure makes the principal comparison a change over time within the treated group. The registry identifies the measurement approach as HOMINGS and the primary outcome as a difference in bacterial count.
The registry record does not report the observed primary outcome values, an estimated change, or measures of statistical uncertainty. It therefore does not establish whether the measured bacterial composition increased, decreased, or remained similar over the specified period, nor how precisely any change was estimated. The patient appearance outcome is also listed without numerical findings.
Even if a before-and-after difference were available, it would be an observed change in this study group rather than a controlled estimate of what SDF caused. Without a concurrent comparison group, changes over time and measurement-related influences cannot be separated from treatment-associated change by the registered design alone. This is a general limitation of single-group before-and-after comparisons.
The record also does not provide enough detail to evaluate the analysis population, missing observations, or methods for handling the count outcome and multiple measures. These limits concern interpretation of the evidence, not proof that a particular result is wrong or that a particular effect occurred. The study’s contribution, as represented by the registry, is the specification of a microbiological question and a measurement time point; the numerical findings needed to assess the result are not reported in the registry record.
13. Why This Trial Matters Statistically
This study raises a statistical question that differs from a conventional comparison between treatment groups: how to describe change in a biological count measured repeatedly in the same group. Repeated observations can be informative because each participant contributes a baseline reference, but the analysis needs to reflect that pairing. The registry describes the time points but does not report how the relationship between repeated measurements was handled.
Bacterial composition also presents measurement and analysis challenges. A count can have a distribution unlike a continuous outcome, and a broad composition measure may involve choices about aggregation and scale. Such choices affect what an estimated difference means. The registry identifies HOMINGS and bacterial count but does not explain the calculation of the overall measure or the statistical model.
The design is important to the scope of any conclusion. Without a separate comparison group, a change from baseline is not by itself a controlled estimate of treatment effect. This distinction helps separate a descriptive biological observation from a causal comparison. The registry’s lack of numerical outcome results adds a further boundary: readers cannot evaluate effect size, direction, or precision from this record.
Finally, the record illustrates why outcome definitions, analysis plans, missing-data descriptions, and detailed results matter alongside a study’s research question. Those elements allow readers to understand what was measured, how it was analyzed, and how much uncertainty remains. Several of these details are not reported in the registry record.
14. Limitations
- The posted summary statistics are the only data these results rest on; patient-level data, full protocols and statistical analysis plans are not available.
- Recalculated results are simple, unadjusted calculations from posted summaries. They do not replace the sponsor's prespecified analysis.
The main limitation for interpreting this trial record is that numerical primary outcome results are not reported. There is no stated bacterial-count change, baseline or follow-up summary, confidence interval, or test result. The registry therefore supports description of the study’s aim and design but not an estimate of the observed microbiological change.
The single-group, unmasked design has no concurrent control group. A baseline-to-follow-up comparison can describe change over time among participants receiving SDF, but the design cannot by itself distinguish treatment-associated change from other temporal or measurement influences. The record does not report details of sample collection, laboratory quality control, or assessor procedures that might help readers judge measurement variability.
The endpoint description does not fully define how bacterial composition was converted into a count or how the difference was calculated. The analysis method, treatment of repeated measurements, and handling of count-data features are not reported. The record also lists three outcome measures without giving results for them or describing multiplicity procedures.
Missing-data handling and the analysis population are not reported. Enrollment of 21 does not show how many participants had complete paired samples or contributed to any analysis. Safety reporting includes broad event counts without event descriptions. Together, these gaps limit assessment of precision, reproducibility, and the scope of the findings.
15. Related Tutorials
16. Related Statistical Calculators
17. Sources
- ClinicalTrials.gov: The Effect of Silver Diamine Fluoride (SDF) on Bacteria Involved in Root or Cervical Carious Lesions — NCT02953886.
- Registry record last updated 2018-09-28; status last verified 2018-09.
- Results first posted 2018-06-25.
- 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.
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18. Record Summary
The registry describes a completed phase 4, single-group study of SDF application to root or cervical carious lesions. Plaque was collected before treatment and one month after application, and bacterial composition was assessed using HOMINGS. Enrollment was 21; the record lists no masking and no separate control group.
The primary outcome was defined as change in bacterial count from baseline to one month after SDF. An appearance-related patient assessment was listed as a secondary outcome, and the record lists three outcome measures. Numerical outcome findings and registered analyses are not reported in the registry record. Serious adverse events were recorded as zero among 21 at risk; other adverse events were recorded as affecting 21 among 21 at risk, without event details. The design and missing results limit quantitative and causal interpretation.