Comparing Pro-Inflammatory Cytokines and Bone Metabolism Mediators Around Laser-Lok and Machined Transmucosal Abutments: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for Comparing Pro-Inflammatory Cytokines and Bone Metabolism Mediators Around Laser-Lok and Machined Transmucosal Abutments (NCT03572244), a randomized na study. The primary outcome is Difference in PICF Cytokine Levels (Log pg/ml) for Various Biomarkers, Specifically at Laser-Lok Abutment Sites and Machined Abutment Sites at 8 Weeks After Implant Placement.

2. Clinical Question

The question is about local biological measurements around two abutment types, not a reported comparison of longer-term clinical outcomes. Peri-implant crevicular fluid is the specimen named in the endpoint description, and the focus is the profile of several pro-inflammatory and bone-metabolism mediators after the stated healing period. The record identifies the trial as a pilot, randomized clinical trial. That makes the comparison useful for describing the study's biomarker objective, but the available record does not establish whether the observed profiles differed, how large any difference was, or how precisely a difference was estimated.

3. Trial Design

The registry identifies a randomized, parallel-group clinical trial with no masking. The two registered interventions were Laser-Lok and Machined; participants were assigned to one of these groups for the comparison. The record describes the study as prospective and as a pilot randomized clinical trial. Its status is completed, and the listed enrollment is 23.

The brief summary describes a proposed recruitment of 12 subjects requiring replacement of a single, toothbound molar or premolar in the maxilla or mandible with an implant-supported restoration. That proposed recruitment figure and the listed enrollment are different registry entries. The record does not explain the relationship between them, so neither should be treated as the number of participants with usable primary-outcome measurements. It also does not report the number analyzed in either group.

The stated primary measurement was obtained 8 weeks after implant placement. The primary outcome description concerns peri-implant crevicular fluid adjacent to the two kinds of healing abutment. The registry gives no further details about the allocation sequence, concealment, visit procedures, or how the biomarker samples were processed. Those design features are not reported in the registry record.

No masking was recorded. In general, an unmasked design means that blinding was not part of the registered design; it does not by itself show whether knowledge of assignment affected sample collection or laboratory measurement. The record does not explain how masking was handled for those activities. It identifies the condition as Dental Implants, lists two outcome measures, and records no posted analyses. Therefore, the design can be described, but its conduct and the resulting comparison cannot be assessed from the registry information alone.

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: Of the 23 enrolled participants, 12 met the inclusion criteria, were randomized to treatment, and completed the study.

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 Difference in PICF Cytokine Levels (Log pg/ml) for Various Biomarkers, Specifically at Laser-Lok Abutment Sites and Machined Abutment Sites at 8 Weeks After Implant Placement, measured over 8 weeks after implant placement.

The primary endpoint is the difference in peri-implant crevicular fluid cytokine levels, expressed as log pg/ml, between Laser-Lok and machined abutment sites at 8 weeks after implant placement. The endpoint description specifically concerns pro-inflammatory cytokines and bone-metabolism mediators, and identifies the summary parameter as a mean with standard deviation. It refers to multiple biomarkers rather than a single named analyte or one overall score.

In general, measuring mediators near an implant can describe local biological activity in the tissue environment. A biomarker endpoint can address a mechanistic or biological question without directly measuring a clinical outcome such as restoration performance. The logarithmic scale expresses concentrations on a transformed scale; differences on that scale should be interpreted as differences in log-transformed measurements, not as raw concentrations.

The registry record does not list the biomarker-specific values, group means, standard deviations, or a comparison estimate. It also does not reduce the multiple categories or time points to one comparison. As a result, the endpoint's intended meaning is clear, but its observed result and precision are not reported in the registry record.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

The registry describes a continuous primary outcome summarized by a mean and standard deviation. It does not report an inferential analysis for that outcome. The following statistical explanations are general and clarify what the registered endpoint and design would ordinarily involve; they are not claims about analyses conducted in this trial.

What does a mean on the log scale represent?

The endpoint is expressed in log pg/ml. A mean on a transformed scale summarizes the transformed observations, rather than the untransformed concentrations. A group comparison on this scale concerns the difference between the groups' average transformed measurements. It should not be silently rephrased as a difference in raw pg/ml. Returning from a log scale to the original scale requires careful attention to the transformation and the distribution of the observations. The registry does not specify the log transformation details or report the values needed to interpret such a comparison.

The standard deviation describes variability among individual measurements on the scale used for analysis. It is not the same as the uncertainty in a group mean or the uncertainty in a between-group contrast. A standard error or confidence interval is generally used to express uncertainty about an estimate. No group-specific standard deviations, contrast standard errors, or confidence intervals are reported for the primary endpoint.

What does randomization contribute?

In general, random allocation is intended to make assigned groups comparable, on average, with respect to factors known and unknown at assignment. It does not guarantee exact balance in a small study, and it does not remove the need to describe who was analyzed or how missing measurements were handled. The registry identifies randomization and a parallel model but does not report allocation procedures or the primary-outcome analysis population.

The design is unmasked. In general, lack of masking can matter when decisions or measurements could be influenced by knowledge of group assignment. The extent of that concern depends on the outcome and study procedures. A laboratory biomarker may be measured using a standardized assay, but the registry record does not state whether laboratory personnel were masked or describe the assay procedures. No conclusion about the effect of masking on measurement quality can be made from the record.

How should a comparison be reported?

For a continuous endpoint, a complete group comparison would ordinarily identify the groups' observed summaries, the estimated contrast, and an uncertainty measure such as a confidence interval. A test result may also be reported, but a p-value alone would not describe the magnitude or precision of a difference. These elements are not present in the registry record for the primary endpoint. The record lists no analyses, so it does not support attributing any particular model, test, adjustment, or estimate to the study.

The endpoint spans various biomarkers, and the registry notes that its categories or time points were not reduced to one comparison. In general, when several outcomes or comparisons are examined, multiplicity can arise: interpreting each result as though it were the only planned test can make chance findings more likely across the family of tests. Approaches can include prespecifying a primary comparison, adjusting inference across a defined family, or treating analyses as exploratory. The registry record does not state which approach, if any, was used. No specific adjustment should be inferred.

What do the planning assumptions mean?

The sample-size assumptions describe a planning illustration based on an observed effect, with a two-sided significance level of 0.05, equal allocation between the two arms, and a normal approximation. The illustration considers detecting a stated fraction of the observed effect. These are planning assumptions, not evidence that the trial was designed using those assumptions or that its own analysis followed them. The registry does not report the trial's sample-size justification.

In general, a planning calculation estimates the number of participants needed under chosen assumptions about an effect, variability, significance level, and desired power. A calculation based on an observed effect is especially sensitive to uncertainty in that effect estimate. Such calculations are illustrative, not a measurement of the trial's achieved power. The record does not provide a reported observed effect estimate for the primary endpoint, nor does it report the numerical planning results in the registry record for this analysis. The planning assumptions therefore cannot fill the gap in the absent outcome analysis.

Normal-approximation methods rely on conditions that make the sampling distribution of an estimate adequately approximated by a normal distribution. Whether those conditions are appropriate depends on the data, sample size, distribution, and analysis model. The registry does not report diagnostics or describe a model for the biomarker data. Likewise, it does not say whether repeated measurements, if any, were modeled jointly. No such method can be attributed to the trial.

Over-dispersion is a general issue for count outcomes when variability exceeds what a chosen count model expects. It is not the stated form of this primary endpoint, which is continuous and summarized by a mean and standard deviation. That general issue should not be conflated with uncertainty or variability in these biomarker measurements.

10. Multiplicity, Missing Data and Analysis Populations

The primary endpoint description covers various pro-inflammatory cytokines and bone-metabolism mediators, rather than one explicitly named measurement. The registry also notes that the primary outcome has several categories or time points and was not reduced to one comparison. Although the record lists two outcome measures, it does not identify a single biomarker contrast as the definitive result.

In general, multiplicity matters when several outcomes, biomarkers, time points, or comparisons are tested. The more results considered, the more important it is to distinguish prespecified confirmatory analyses from exploratory analyses and to explain any adjustment or hierarchy used. The registry record does not report a multiplicity strategy, the full analysis plan, or the analyses performed. It is therefore not possible to determine how the investigators handled the family of possible comparisons.

Missing-data handling is also not reported in the registry record. The enrollment figure does not establish how many participants had an 8-week sample or a usable measurement for each mediator. The record does not give reasons for missing measurements, describe imputation, or state whether analyses used complete cases or another approach.

The analysis population is not specified. In general, an analysis population should clarify which randomized participants are included and how deviations from assignment or incomplete follow-up are treated. No such definition, arm-specific endpoint count, or participant flow is reported. With no posted analyses, outcome data, or missing-data description, the registry record does not support a judgment about the completeness or robustness of the biomarker comparison.

11. 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 and other adverse-event counts separately for the Laser-Lok and Machine groups. For each group, 6 are recorded at risk for serious adverse events and 6 at risk for other adverse events. The reported count affected is 0 for serious events and 0 for other events in each group; deaths are recorded as 0 in each group. No serious-event terms are listed.

These figures describe what was recorded in the registry for the listed at-risk groups. They do not establish that no events occurred outside the recorded reporting scope, and they do not show how adverse events were defined, collected, or adjudicated. The registry does not explain the relationship between these at-risk counts and the overall enrollment of 23 or state whether they represent everyone who received an intervention.

In general, zero recorded events in a group does not establish that the underlying risk is zero. The amount of uncertainty depends in part on the amount and completeness of follow-up and on how events were ascertained. The record does not provide enough detail to assess those features. These counts should therefore be read as registry-recorded adverse-event figures, not as a comprehensive estimate of comparative safety.

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

The registry record describes a randomized comparison of Laser-Lok and machined abutments focused on local biomarker levels at 8 weeks after implant placement. It identifies the specimen, the types of mediators of interest, the log-scale unit, and the intended summary as a mean with standard deviation. It also identifies the study as a pilot and reports an enrollment of 23.

What the record does not provide is the outcome evidence needed to interpret the comparison. There are no group means, standard deviations, between-group estimates, confidence intervals, or analysis results for the primary endpoint. The direction, magnitude, and precision of a difference are therefore unknown from the registry record. The study's completion status does not substitute for posted results.

Even if biomarker results were available, a difference in local mediator levels would not by itself establish a difference in patient-important clinical outcomes. In general, biomarkers describe biological measurements and may be informative about a biological process, but they are not interchangeable with clinical outcomes. The record's primary question is limited to measured mediator profiles; it does not report a clinical outcome comparison that could support broader conclusions.

The registry's adverse-event figures record zero affected in the listed at-risk groups, but those counts do not establish the absence of risk or provide a complete comparison of safety. The number of participants with primary-outcome data, missing-data methods, multiplicity handling, and analysis population are not reported. Those omissions constrain interpretation of both efficacy-related biomarker findings and safety reporting.

The careful conclusion is that the registered design and scientific question can be described, but the posted results do not show whether biomarker levels differed between groups. No claim that either abutment type produced higher or lower levels, or that a difference was important, can be made on the basis of the registry record alone.

13. Why This Trial Matters Statistically

This trial is statistically interesting because it frames a randomized comparison around local biological measurements rather than a single conventional clinical outcome. The endpoint concerns several pro-inflammatory cytokines and bone-metabolism mediators in peri-implant crevicular fluid, measured at a defined time after implant placement. That creates a setting in which the choice of summary, scale, and comparison matters: the endpoint is continuous, expressed in log pg/ml, and described using means and standard deviations.

The record also illustrates why a clear analysis plan is important when an endpoint includes multiple biomarkers or categories. Without identifying the principal contrast and explaining how multiple comparisons are handled, readers cannot distinguish a confirmatory result from a collection of exploratory findings. Here, the registry explicitly notes that the outcome has several categories or time points and was not reduced to one comparison, while listing no analyses.

The gap between the record's design information and its absent outcome analysis is consequential. Randomization and a completed status describe important aspects of the trial, but they do not reveal the observed group differences, uncertainty, missingness, or analysis population. Likewise, a planning illustration based on an observed effect is not a substitute for a reported estimate and is not observed power.

For clinical researchers, the case underscores the need to report group summaries, an interpretable contrast, uncertainty, participant flow, and multiplicity and missing-data methods. Without these elements, the biological question is recognizable but the evidence needed to assess its answer is unavailable 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 is that the registry record contains no posted primary-outcome analysis. It does not report biomarker-specific group summaries, effect estimates, uncertainty intervals, or test results. Consequently, no direction, magnitude, or precision of the comparison can be evaluated.

The record identifies several biomarkers and says that the primary outcome has several categories or time points, but it does not state how these were organized into analyses. No multiplicity procedure or outcome hierarchy is reported. Missing-data methods, the analysis population, and arm-specific numbers contributing primary measurements are also not reported.

Although the listed enrollment is 23, the brief summary describes a proposed recruitment of 12 subjects. The record does not explain this difference or establish the number with completed 8-week measurements. The adverse-event at-risk counts likewise are not reconciled with the overall enrollment. These details should not be inferred from one another.

The trial is labeled a pilot and was unmasked. The registry does not report the allocation procedure, laboratory masking, biomarker assay details, or the statistical plan. It also does not provide a sample-size justification for the trial. The listed planning assumptions are an illustration based on an observed effect and should not be mistaken for the trial's original design rationale or achieved power.

Finally, the registered endpoint is a biomarker comparison at 8 weeks. The record does not provide evidence about longer-term outcomes or establish how any biological difference would relate to clinical outcomes. These limitations reflect what is and is not documented in the registry record, rather than evidence that a particular result occurred.

15. Related Tutorials

16. Related Statistical Calculators

17. Sources

• ClinicalTrials.gov: Comparing Pro-Inflammatory Cytokines and Bone Metabolism Mediators Around Laser-Lok and Machined Transmucosal Abutments — NCT03572244.
• Registry record last updated 2022-01-03; status last verified 2021-12.
• Results first posted 2022-01-03.
• 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.

18. Record Summary

NCT03572244 is a completed, randomized, unmasked, parallel pilot clinical trial comparing Laser-Lok and machined abutments. The registry lists an enrollment of 23 and describes a proposed recruitment of 12 subjects requiring an implant-supported restoration for a single, toothbound molar or premolar.

The primary endpoint concerns mean peri-implant crevicular fluid levels of pro-inflammatory cytokines and bone-metabolism mediators, expressed in log pg/ml, at 8 weeks after implant placement. The registry lists two outcome measures and no analyses. It does not post primary-outcome results, group summaries, or uncertainty estimates. The recorded adverse-event counts are zero affected in the listed groups, with 6 at risk for each event category in each group.

The registry record identifies the study question and broad design but does not allow the biomarker comparison's direction, size, or precision to be assessed.