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 Effect of Locally-Applied Simvastatin on Clinical Attachment Level and Alveolar Bone in Periodontal Maintenance Patients (NCT03452891), a randomized phase 4 study. The primary outcome is Change in Clinical Attachment Level (CAL).
| Feature | Registry value |
|---|---|
| ClinicalTrials.gov identifier | NCT03452891 |
| Phase | Phase 4 |
| Condition | Periodontal Diseases |
| Allocation | Randomized |
| Design model | Parallel |
| Masking | Triple |
| Enrollment | 50 |
| Arms in the primary outcome | 2 |
| Lead sponsor | University of Nebraska |
| Results posted | Yes |
2. Clinical Question
The clinical question concerns whether adding locally applied simvastatin to mechanical periodontal treatment is associated with a different change in clinical attachment level (CAL) than applying methylcellulose gel alone. The study focused on people receiving periodontal maintenance who had chronic advanced periodontitis and an eligible periodontal pocket.
Population
Participants were receiving periodontal maintenance and had chronic advanced periodontitis, generalized or localized. Eligibility also called for an inflamed 6-9 mm interproximal posterior pocket with a history of bleeding on probing, regular maintenance visits, and good general health without listed systemic diseases or medications considered likely to affect periodontal inflammation or bone turnover.
Intervention
After local anesthesia, mini-flap reflection, and subgingival mechanical debridement, the intervention group received simvastatin in methylcellulose gel in the experimental pocket.
Comparator
The comparison group received the same described local anesthesia, mini-flap reflection, and subgingival mechanical debridement, followed by methylcellulose gel alone.
Primary question
At 12 months, what mean change in CAL was recorded in each group, and how precisely did the posted unadjusted comparison distinguish the group means? The registry lists alveolar bone as a secondary outcome in the study description, but no secondary outcome results are posted.
3. Trial Design
The registry describes a randomized, triple-masked, parallel-group phase 4 trial with an enrollment of 50. The study status is completed. The recorded start date is 2019-03-01, and the primary completion date is 2020-07-31. The two posted groups each contain 25 participants: SIM-MCL and Methylcellulose Gel.
Both groups received local anesthesia, mini-flap reflection, and subgingival mechanical debridement in an experimental periodontal pocket. The difference in the described additional therapy was the gel: simvastatin in methylcellulose for SIM-MCL, versus methylcellulose gel alone for the comparator. This arrangement addresses the contrast between the drug-containing gel and its gel comparator in the context of the described mechanical treatment.
The study description identifies participants as people undergoing periodontal maintenance at the University of Nebraska Medical Center College of Dentistry clinics. Eligibility included chronic advanced periodontitis, regular maintenance visits at 3-6 month intervals, and an inflamed 6-9 mm interproximal posterior pocket with a history of bleeding on probing. The description also lists exclusions or health requirements concerning systemic disease and medications that may affect periodontal inflammation or bone turnover. The registry's summary includes an aspirin threshold written as > 325 mg/day.
The primary outcome is change in CAL measured at 12 months. Although the study description names alveolar bone as a secondary outcome, the registry lists no posted secondary results. The masking label is triple, but which groups of people were masked and the practical masking procedures are not reported in the registry record. Details of sequence generation, concealment, adherence, participant flow, and the original design assumptions are 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 | SIM-MCL | Methylcellulose Gel |
|---|---|---|
| STARTED | 25 | 25 |
| Subjects Enrolled | 25 | 25 |
| Subjects Completing Study | 25 | 25 |
| COMPLETED | 25 | 25 |
| NOT COMPLETED | 0 | 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.
Population: Fifty periodontal maintenance subjects with chronic inflammation participated in this study.
| Characteristic | Unit | SIM-MCL | Methylcellulose Gel | Total |
|---|---|---|---|---|
| Participants analysed | 25 | 25 | 50 | |
| Age, Categorical: <=18 years | Participants | 0 | 0 | 0 |
| Age, Categorical: Between 18 and 65 years | Participants | 17 | 20 | 37 |
| Age, Categorical: >=65 years | Participants | 8 | 5 | 13 |
| Sex: Female, Male: Female | Participants | 18 | 20 | 38 |
| Sex: Female, Male: Male | Participants | 7 | 5 | 12 |
| Race and Ethnicity Not Collected | Participants | — | — | 0 |
6. Primary Endpoint
The registry lists the primary outcome as Change in Clinical Attachment Level (CAL), measured over The CAL will be measured at 12-months..
| Element | Registry entry |
|---|---|
| Result type | Mean |
| Measure of spread | Standard Error |
| Unit | millimeters |
| Endpoint classification | Continuous Endpoint |
The primary endpoint is change in clinical attachment level (CAL), a continuous periodontal measurement recorded in millimeters. The registry states that CAL change is measured by measuring recession and subtracting periodontal probing depth, with assessment at 12 months. The group summaries are reported as means with standard errors.
CAL is used to describe the supporting attachment around a tooth. As a general statistical and clinical measurement concept, tracking change in a continuous measure can capture differences across a range of values rather than reducing the result to a binary category. In this trial, the endpoint was selected to assess the study's stated question about clinical attachment after the additional local gel treatment.
The registry reports mean values of 7.0 for SIM-MCL and 6.9 for methylcellulose gel. These are the values posted for the primary outcome; the registry description identifies the assessment time as 12 months. The brief outcome description does not clarify the sign convention for change or provide a baseline summary alongside these values. Therefore, the means should be read as posted, without inferring from their magnitudes alone whether an increase represents improvement or deterioration.
Alveolar bone is mentioned as a secondary outcome in the study description, but no secondary outcome results are posted. The endpoint data therefore speak only to the registered primary measure in the available results; they do not provide a numerical account of the bone outcome.
7. Results Posted in the Registry
- Methylcellulose Gel: mean 6.90 versus 7.00 on control; difference -0.10 (95% CI -0.54 to 0.34), standardized effect d = -0.13; z-test p = 0.655.
Mean difference: Methylcellulose Gel
95% CI: -0.54 to 0.34
Recalculated from the posted summary statistics
8. Statistical Interpretation
The registry reports 25 participants in each group and primary outcome means of 7.0 for SIM-MCL and 6.9 for methylcellulose gel. The posted comparison is a mean difference of -0.1, with the comparator as the methylcellulose gel group relative to SIM-MCL. The estimate is small relative to the uncertainty reflected by its confidence interval, which spans values on both sides of zero. The unadjusted p-value is 0.655.
In general, a confidence interval describes a range of values compatible with the data and the statistical procedure, under its assumptions. Here, because the interval includes zero, the posted summary does not distinguish the group means clearly at the conventional two-sided 0.05 significance level used in the planning illustration. The p-value likewise does not provide strong evidence against a zero mean difference under the unadjusted comparison. Neither result establishes that the groups are identical; the interval's breadth means that materially different underlying contrasts remain compatible with the estimate.
The comparison is labeled as recalculated from the posted summary statistics, rather than as a sponsor-reported adjusted analysis. The registry record lists no analysis records. The recalculated result is unadjusted, and no adjustment for covariates, clustering, multiple outcomes, or other features is reported in the registry record. The record does not describe an analysis population, how missing measurements were handled, or whether the reported summaries include all randomized participants. Those gaps constrain how specifically the estimate can be interpreted.
The trial enrolled 50 participants, with 25 shown in each arm. A small study can yield an imprecise estimate even when its point estimate is close to zero. A non-small p-value is not evidence that the treatments have been shown equivalent: equivalence requires a prespecified margin and an analysis designed to assess whether the uncertainty lies within that margin. Such a margin and an equivalence analysis are not reported in the registry record.
The study description also proposes alveolar bone as a secondary outcome, but no secondary results are posted. Consequently, the primary CAL result cannot stand in for a result on bone. The registry outcome record also does not establish effects beyond the 12-month CAL assessment named for the primary endpoint. Overall, the posted data give a near-zero mean contrast with substantial uncertainty, rather than a precise estimate that rules out meaningful differences in either direction.
9. Statistical Methods Explained
The reported design and outcome summaries support a limited statistical reading. The trial is described as randomized, triple-masked, and parallel-group, with 25 participants reported in each group. The primary measure is continuous, and the registry presents each group's mean with a standard error. The comparison summary is an unadjusted recalculation from these posted summaries; the registry lists no analysis records.
What does a mean summarize?
As a general statistical concept, a mean is an average of the measured values in a group. It gives a compact description of the group's central level, but does not show the distribution of individual measurements. Different distributions can share the same mean. The registry reports means of 7.0 for SIM-MCL and 6.9 for methylcellulose gel for the primary CAL outcome. It does not post individual participant observations or a distributional summary such as a range.
What does the standard error describe?
As a general explanation, a standard error describes the estimated sampling variability of a statistic, such as a mean. It is not the same as the spread of individual participant measurements. The registry reports standard errors of 0.1 for SIM-MCL and 0.2 for methylcellulose gel. The underlying group-level standard deviations are not directly reported in the outcome summaries. The registry's comparison calculation includes a pooled standard deviation, but that is part of a recalculation rather than a separate participant-level result.
How should the mean contrast be read?
The posted contrast is -0.1 for methylcellulose gel relative to SIM-MCL. In general, a difference between group means expresses how far apart the two reported averages are, using a stated subtraction order. The sign depends on which group is subtracted from which. It is important to retain that direction when reading the result; the sign alone does not indicate clinical benefit, especially when the registry does not clarify the endpoint's sign convention for change in the outcome description.
The comparison is unadjusted. In general, an unadjusted comparison uses the stated group summaries without accounting for additional variables in a regression or other adjusted model. The registry record does not report covariate adjustment, a model for repeated measurements, or a method for addressing other design features in an analysis. No adjusted estimate should be inferred from the posted summaries.
What does a confidence interval add?
As a general explanation, a confidence interval combines an estimate with its statistical uncertainty, under a specified method and assumptions. It helps show which values are reasonably compatible with the data, rather than presenting a point estimate alone. The interval reported for the mean difference includes zero and extends to values on both sides. This means the summaries do not precisely settle whether the underlying group contrast is negative or positive. The exact interval endpoints are not needed to recognize that the estimate is uncertain and compatible with no mean difference.
Confidence intervals do not account automatically for every source of uncertainty. For example, an interval from a simple unadjusted calculation does not resolve possible missing measurements, departures from model assumptions, or multiplicity. The registry record does not provide enough information to determine how those issues were handled in the trial's original analysis.
What does the p-value say?
As a general explanation, a p-value measures how unusual the data or a more extreme result would be if a specified null hypothesis and statistical model were true. The posted unadjusted p-value is 0.655. It does not give the probability that the null hypothesis is true, and it does not measure the size or clinical importance of an effect. Read alongside the interval, it indicates that the posted result does not provide a strong statistical distinction from zero under the unadjusted comparison. It does not prove equality.
The registry's planning illustration describes a two-sided significance level of 0.05, equal allocation, and a normal approximation. These are assumptions for the displayed planning exercise, not evidence of the trial's original analysis plan. The original sample-size assumptions and any prespecified interim or final analysis procedures are not reported in the registry record.
Why does over-dispersion matter in general?
As a general statistical concept, over-dispersion occurs when observed variability exceeds what a model assumes. If variability is understated, standard errors may be too small and intervals too narrow; if variability is modeled appropriately, uncertainty is better represented. This trial's primary outcome is continuous and its posted summaries include standard errors, but the registry record does not report an over-dispersion assessment or identify a model that would require one. Over-dispersion should therefore be treated as a general methods issue, not as a documented feature of this trial.
More broadly, the available record does not report participant-level data, an analysis population, handling of missing outcomes, or a full statistical analysis plan. These omissions prevent independent verification of the reported summaries and limit assessment of whether the recalculated comparison matches the trial's intended analysis. The main interpretation should remain anchored to the posted group means, the unadjusted comparison, and its uncertainty.
10. Confidence Intervals and Precision
The mean difference is -0.1, and the unadjusted p-value is 0.655. The registry's confidence interval for this contrast spans zero, with compatible values on both the negative and positive sides. This is the central precision point: the estimated difference is small, but the data do not pin down the direction of the underlying contrast with confidence.
As a general explanation, a confidence interval is a range produced by a statistical procedure that reflects sampling uncertainty under its assumptions. A narrower interval indicates greater precision for the parameter being estimated; a wider interval indicates less precision. An interval that includes zero does not establish that the true difference is zero. It indicates that zero remains compatible with the result, as do some nonzero contrasts covered by the interval.
The registry posts standard errors of 0.1 and 0.2 for the SIM-MCL and methylcellulose gel means, respectively. These describe uncertainty around the group means, not the spread of individual measurements. Each group has 25 participants in the posted summary. With a modest number of participants, the estimated contrast can remain uncertain even when the group means are close.
The confidence interval and p-value are from an unadjusted recalculation based on posted summary statistics. The registry record does not report whether the original trial analysis used a different method, whether all randomized participants contributed outcome data, or how missing data were addressed. Precision should therefore be interpreted as precision of the posted unadjusted comparison, not as a complete account of every uncertainty affecting the trial.
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 | 982 | 1,314 |
| 75% of the observed effect | 1,745 | 2,335 |
| 50% of the observed effect | 3,925 | 5,254 |
The sample-size illustration is a planning exercise based on the observed effect, not a report of the trial's original design calculation. Its entries are participants per arm, not total events. It assumes a two-sided significance level of 0.05, equal allocation between the two arms, and a normal approximation; the effect to detect is the stated fraction of the observed effect. The original trial's sample-size assumptions are not reported in the registry record.
The 80% power column describes the planned number of participants per arm for a design that, under the stated assumptions and effect size, would have an 80% chance of detecting an effect at the specified significance level. The 90% column describes the corresponding planning target for a 90% chance. These are design probabilities conditional on the assumed effect and statistical model; they do not describe what happened in the completed trial.
The rows consider planning for 100%, 75%, and 50% of the observed effect. In the illustration, the participant requirements rise as the assumed effect becomes smaller. This is a general feature of power planning: smaller effects are harder to distinguish from random variation, so more participants are generally needed when other assumptions are held fixed. The plotted curve expresses this relationship graphically, while the entries give planning values for the listed effect fractions.
These numbers are not observed power. They are hypothetical planning illustrations derived from the posted effect estimate and the stated assumptions, not a retrospective measure of the probability that the trial succeeded. Because the observed effect itself is uncertain, planning from it should be treated as illustrative rather than as a definitive sample-size recommendation.
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 = -0.100; pooled standard deviation σ = 0.791.
- n = 2 × (1.96 + 0.842)2 × 0.7912 / -0.1002 = 981.1, rounded up to 982 participants per arm for 80% power.
The smaller-effect rows in the table above repeat the same calculation with the effect multiplied by 0.75 and 0.5 (for ratios, applied to the logarithm of the ratio).
R code
alpha <- 0.05
z_a <- qnorm(1 - alpha / 2) # two-sided
delta <- -0.0999999999999996 # observed difference in means
sigma <- 0.790569415042095 # 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(3452891)
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 = 982 (80% power), 1,314 (90% power)
75% of observed effect: n per arm = 1,745 (80% power), 2,335 (90% power)
50% of observed effect: n per arm = 3,925 (80% power), 5,254 (90% power)
power.t.test: 982.1
Simulated power at n = 982 per arm: 0.802 (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 lists one primary outcome measure: change in CAL at 12 months. It also describes alveolar bone as a secondary outcome, but no secondary outcome results are posted. The number of posted outcome measures is one, and the registry lists no analysis records. These details do not establish how many outcomes, time points, or analyses were planned in the full study protocol.
Multiplicity arises in general when multiple statistical hypotheses or comparisons are assessed. If many tests are considered, the chance of at least one apparently unusual result can increase unless the analysis plan accounts for that testing. Whether multiplicity adjustment was needed or planned for this trial is not reported in the registry record. The posted p-value is identified as unadjusted; no multiplicity correction is described. The original statistical analysis plan and any prespecified hierarchy among outcomes are not reported in the registry record.
Missing-data handling is also not reported in the registry record. The group summaries list 25 participants per arm, but that alone does not establish how many had a 12-month CAL measurement, whether every randomized participant was included in the outcome calculation, or how any absent measurement was handled. No imputation method, complete-case rule, or sensitivity analysis is described. The participant flow and reasons for any missing outcomes are not reported in the registry record.
The analysis population is not reported in the registry record. In general, a trial may describe an intention-to-treat population, a per-protocol population, or another defined set of participants; those choices affect the interpretation of results. The randomized design does not, by itself, show which population was used for the posted outcome summaries.
These gaps matter because the precision and validity of an estimated treatment contrast depend not only on group means and standard errors, but also on which participants contributed data, how outcomes were handled, and what comparisons were planned. The posted unadjusted comparison can be described as recorded, but the absent analysis details prevent a fuller evaluation of multiplicity, missingness, and population selection.
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 |
|---|---|---|---|
| SIM-MCL | 0 | 25 | 0.0% |
| Methylcellulose Gel | 0 | 25 | 0.0% |
Deaths
| Arm | Deaths (participants affected of at risk) |
|---|---|
| SIM-MCL | 0 of 25 |
| Methylcellulose Gel | 0 of 25 |
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 |
|---|---|
| SIM-MCL | 0 of 25 |
| Methylcellulose Gel | 0 of 25 |
The registry reports serious adverse events for 0 of 25 participants in SIM-MCL and 0 of 25 in the methylcellulose gel group. It also reports other adverse events for 0 of 25 participants in each group, and deaths of 0 in each group. No serious adverse event terms are listed.
These figures describe what is reported in the registry record. They should not be read as proof that no adverse experiences occurred in any broader sense: the entries indicate zero participants affected in the posted categories, while the record does not provide additional detail about collection procedures, event definitions, observation windows, or completeness of reporting. The record also does not explain whether adverse events were actively solicited or how events were attributed.
Counts of zero in both groups provide no observed between-group difference in these posted categories, but a small trial and limited event detail cannot establish that risks are identical. The figures are a descriptive safety summary for the reported groups, not a comprehensive estimate of the frequency of uncommon events.
15. What the Result Does, and Does Not, Mean
The registry result describes a randomized comparison of two locally applied gels in the setting of mechanical periodontal treatment. For the 12-month primary CAL measure, the posted means are 7.0 for SIM-MCL and 6.9 for methylcellulose gel. The unadjusted recalculated mean difference is -0.1, and the confidence interval spans zero. The p-value is 0.655. Together, these statistics show a small estimated contrast with substantial uncertainty in its direction and size.
This does not establish that the groups are equivalent. A claim of equivalence would require a defined margin for a clinically unimportant difference and an analysis designed to test that question; neither is reported in the registry record. Nor does the result establish that one treatment is superior. The interval includes zero, and the posted comparison does not clearly separate the means.
The result also does not settle the study's stated secondary question about alveolar bone. Although bone is named in the study description, no secondary outcome results are posted. The recorded primary outcome is CAL at 12 months; the registry record does not provide a basis for extending the result to other outcomes or later time points.
Interpretation is further limited by missing analysis details. The registry record does not report an analysis population, a missing-data method, a detailed masking procedure, or the original statistical analysis and sample-size plans. The group counts in the outcome summary do not by themselves confirm the number of participants with observed 12-month measurements.
The most defensible reading is therefore narrow: the available registry summaries show similar group means, with an unadjusted estimate close to zero but an interval broad enough to retain uncertainty. They neither demonstrate an important difference nor rule one out. They describe the posted CAL result only, not a complete evaluation of all study outcomes, safety, or treatment effects.
16. Why This Trial Matters Statistically
This trial is statistically instructive because it pairs a randomized, parallel-group comparison with a continuous primary endpoint and a modest posted group size. It illustrates why a point estimate alone is not enough. The mean difference of -0.1 appears small, but its confidence interval spans zero and the unadjusted p-value is 0.655. The uncertainty, rather than the proximity of the group means alone, is central to interpreting the result.
The record also illustrates the distinction between a result and a design calculation. The sample-size illustration scales planning assumptions from the observed effect, with higher participant requirements for smaller assumed effects. Those figures are not observed power and are not evidence of the trial's original sample-size rationale. The original design assumptions are not reported in the registry record.
Another useful statistical distinction is between a zero-difference finding and evidence of equivalence. The posted comparison does not clearly distinguish the means, but no equivalence margin or equivalence analysis is described. A lack of a statistically clear difference cannot, by itself, establish that any difference is unimportant.
Finally, the incomplete posted analysis record shows why endpoint and analysis details matter. CAL is the sole posted outcome result, while alveolar bone is mentioned only as a secondary outcome without results. Missing information about analysis populations, missing measurements, and multiplicity narrows what can be inferred. Careful interpretation separates the reported primary endpoint estimate from unreported analyses and outcomes.
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 registry record leaves several trial-specific limitations unresolved. Although it labels the study randomized and triple-masked, it does not describe how the allocation sequence was generated or concealed, nor which participants, clinicians, or assessors were masked. The detailed masking procedures are not reported in the registry record.
The primary outcome description gives the CAL measurement approach and 12-month timeframe, but does not clarify the sign convention for change or provide baseline CAL summaries. The posted values therefore cannot be used to infer the direction of clinical change from their magnitude alone. The registry also does not provide individual measurements or a distributional account of the outcome.
The outcome record reports 25 participants per group, but does not identify the analysis population or confirm how many had measurements at the stated assessment. Participant flow, losses to follow-up, protocol deviations, and missing-data handling are not reported in the registry record. No detailed statistical analysis plan, covariate adjustment, multiplicity procedure, or sensitivity analysis is reported. The original sample-size rationale and any interim analyses are not reported in the registry record.
The registry describes alveolar bone as a secondary outcome, but posts no secondary results. The available numerical evidence is therefore confined to the primary CAL measure. Adverse event figures list zero affected participants in both groups, but details about event ascertainment, definitions, and reporting completeness are not reported in the registry record.
These limitations do not alter the posted numbers; they constrain the scope of interpretation. The results support description of the reported group means and unadjusted comparison, but not a comprehensive assessment of all planned outcomes or of the trial's full analysis process.
18. Related Tutorials
19. Related Statistical Calculators
20. Sources
- ClinicalTrials.gov: Effect of Locally-Applied Simvastatin on Clinical Attachment Level and Alveolar Bone in Periodontal Maintenance Patients — NCT03452891.
- Registry record last updated 2023-10-05; status last verified 2023-09.
- Results first posted 2023-02-09.
- 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
NCT03452891 is a completed randomized, triple-masked, parallel-group phase 4 trial sponsored by the University of Nebraska. The record lists an enrollment of 50, with 25 participants in each group. The recorded study start date is 2019-03-01 and primary completion date is 2020-07-31.
The trial compared simvastatin in methylcellulose gel with methylcellulose gel alone, alongside described mechanical treatment. The primary outcome was change in CAL at 12 months. The registry reports means of 7.0 and 6.9, respectively, and a recalculated unadjusted mean difference of -0.1 with p = 0.655. The confidence interval spans zero. Alveolar bone is named as a secondary outcome, but secondary results are not posted. The registry reports zero serious adverse events, other adverse events, and deaths in both groups.