Bone Graft Particle Size on Bone Vitality and Volume: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for Bone Graft Particle Size on Bone Vitality and Volume (NCT04778709), a randomized na study. The primary outcome is Quality of Bone.

2. Clinical Question

3. Trial Design

This was a randomized, double-masked, split-mouth study. The registry also classifies its model as crossover. Those labels indicate that the trial was intended to compare graft approaches under a randomized and masked design, with the split-mouth framework relevant to how treatment comparisons are made. The registry does not explain the allocation sequence, masking procedures, side assignment, or the operational details of the crossover classification. Those details are not reported in the registry record.

The planned materials were Bone Graft A, a mixture of 25% small-particle cortical, 25% large-particle cortical, 25% small-particle cancellous, and 25% large-particle cancellous allograft, and Bone Graft B, 100% large-particle cancellous allograft. The registry lists Puros allograft as a device intervention. The study concerned sinus augmentation for dental implant placement.

The recorded enrollment was 4. The study is marked terminated. Its primary completion date is 2022-02-01, and its start date is 2020-11-13. The registry says that data were not collected and that the original principal investigator was no longer at the institution; the sponsor, Zimmer Biomet, and the current principal investigator decided to close enrollment and terminate the study early. The record does not state how many participants completed procedures or had outcome assessments.

The primary outcome was Quality of Bone, with measures intended to include percent vital bone formation and percent inflammatory tissue, if any. The listed assessment timeframe was after surgery, 8 months, and 1 year. Bone Volume Stability is listed as a secondary outcome. Although the registry lists four outcome measures, it reports no statistical analyses. A rationale for the planned enrollment and fuller design details 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

Analysis population for the primary outcome, as defined in the registry: Data were not collected. The original PI who is no longer at the institution, the sponsor of this research study, Zimmer Biomet, along with the current PI has decided to close enrollment to the study and to early terminate the 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 Quality of Bone, measured over After surgery, 8 months, 1 year.

The primary outcome is titled Quality of Bone. It was intended to assess the quality of bone generated in grafted sinuses by measuring percent vital bone formation and percent inflammatory tissue, if any. The listed timeframe was after surgery, 8 months, and 1 year. The record does not provide outcome values, measurement results, or a statistical comparison for these measures.

These measures address tissue composition at a grafted site. In general, histological assessments can describe the tissue present in a biopsy, rather than relying only on an image-based estimate. The study summary says that bone biopsies from grafted sites were to be taken at dental implant placement for histological measurement. It also describes postoperative dental radiographs to estimate differences in bone-graft volume. Bone Volume Stability is listed as a secondary outcome, but the primary outcome description specifically names vital bone formation and inflammatory tissue.

Such measures can help characterize biological and structural features of a grafted site, but they are not interchangeable: tissue composition and radiographic volume represent different kinds of observations. The registry does not report results for either. It explicitly states that data were not collected, so the endpoint cannot be used to estimate a difference between the graft approaches or the precision of such a difference.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

Randomization, masking, and the split-mouth structure address different aspects of a trial. Randomization is intended to reduce systematic differences in how study conditions are assigned. Masking is intended to limit the influence of knowledge about assignment on care, measurement, or reporting. A split-mouth design compares conditions at sites within the same participant, which can help control characteristics shared by those sites’ host. The registry labels this study randomized, double-masked, and split-mouth, and classifies its model as crossover. The procedures used to implement these features are not reported in the registry record.

What does a split-mouth comparison require?

In general, a split-mouth analysis should preserve the relationship between measurements from the same participant. Outcomes from sites within one person are not necessarily independent: shared biological features, care, and other participant-level factors may make the measurements more alike than measurements from unrelated people. A paired analysis uses that within-participant structure. Treating each site as independent can misrepresent uncertainty when the pairing is ignored. These are general methodological considerations, not a description of an analysis performed in this study.

The appropriate analysis would also depend on what was measured and when. Percent vital bone and percent inflammatory tissue are bounded proportions; their distributions and variability may not always suit a simple normal model. Radiographic estimates of bone volume have a different measurement scale and may call for a different model. Repeated assessment times can create additional within-participant dependence. If the same outcome is assessed at multiple times, an analysis needs to account for the relationship among measurements rather than treating every observation as unrelated.

Why does uncertainty matter?

In general, an effect estimate describes the observed contrast between conditions, while a confidence interval describes the range of values compatible with the data under the analysis assumptions. A narrow interval indicates greater precision than a wide interval; an interval that includes values consistent with little difference does not establish equivalence. A p-value addresses compatibility with a specified null model and is not a measure of effect size or clinical importance. None of these quantities is available for the primary outcome in this registry record because the data were not collected and no analyses are reported.

Variation also matters when planning and analyzing outcomes. In general, over-dispersion means that observed variability is greater than expected under a chosen model. If it is not accounted for, uncertainty can be understated. This is a general statistical point, not a claim that the study’s outcome data were over-dispersed. No outcome data are posted from which such a property could be assessed.

What can planning calculations say?

Sample-size planning illustrations are conditional calculations: they depend on an assumed effect, variability, significance level, allocation, and analysis approach. The registry’s stated planning assumptions refer to a two-sided significance level of 0.05, equal allocation, a normal approximation, and effects expressed as fractions of an observed effect. For non-time-to-event calculations, the stated unit is participants per arm; for time-to-event calculations, it is total events. These assumptions describe planning illustrations, not the trial’s own design justification. The sample-size justification is not reported in the registry record.

Because no primary outcomes were collected, an observed primary effect from this study is not available to anchor an effect-based planning illustration. Such calculations should never be interpreted as observed power, which is not a substitute for an effect estimate and its uncertainty. No primary outcome estimate, confidence interval, or p-value is reported. The registry also does not report an interim-analysis plan, a statistical analysis plan, model specifications, or an analysis population.

For a paired study, sample-size planning would generally need to reflect the number of paired observations and the degree of within-participant association, as well as the outcome’s variability and the target effect. Planning for an independent-groups design may not represent the efficiency or uncertainty of a paired comparison. These are general considerations. The registry does not state how its split-mouth structure was incorporated into planning.

How should multiple outcomes and time points be handled?

In general, testing multiple outcomes or time points can increase the chance of at least one apparently notable result when each is assessed separately. A statistical plan may define a primary comparison, prespecify an approach to multiplicity, and distinguish confirmatory from exploratory analyses. The record identifies Quality of Bone as the primary outcome and lists a timeframe of after surgery, 8 months, and 1 year. It does not report how those time points or the four listed outcome measures would be handled statistically. No multiplicity adjustment or hierarchy is reported in the registry record.

These explanations describe statistical principles rather than methods known to have been used in this trial. With no collected primary data and no analyses posted, the design labels and stated planning assumptions cannot substitute for an estimate of comparative effect.

10. Multiplicity, Missing Data and Analysis Populations

The primary outcome is titled Quality of Bone and includes percent vital bone formation and percent inflammatory tissue, if any. Its listed timeframe is after surgery, 8 months, and 1 year. The registry also lists Bone Volume Stability as a secondary outcome and reports four outcome measures overall. Multiple measures and assessment times can create multiplicity concerns if each is tested separately. In general, a prespecified hierarchy or adjustment may help control the interpretation of repeated testing. The registry does not report a multiplicity strategy, an outcome hierarchy beyond identifying the primary outcome, or which comparisons were intended at each time point.

For missing data, the key fact is stronger than an unspecified amount of missingness: the registry states that data were not collected for the primary outcome. It does not provide participant-level completion information, missingness patterns, reasons for missing outcome measurements beyond the study closure explanation, or a method for handling missing data. Imputation, complete-case analysis, or another missing-data method is not reported in the registry record. With no posted primary measurements, no sensitivity analysis of missing outcomes can be evaluated.

The registry does not identify an intention-to-treat, per-protocol, or other analysis population. It reports 0 analyses. The recorded enrollment is 4, but the record does not clarify the number with completed procedures, paired measurements, or follow-up at the listed assessment times. These omissions prevent assessment of the intended analysis set, attrition, or the influence of incomplete follow-up. No statistical analysis plan or interim-analysis plan is reported in the registry record.

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 records 0 serious adverse events, 0 other adverse events, and 0 deaths for Bone Graft A and for Bone Graft B. The group records each list 2 at risk. These are registry counts, not evidence that every possible event was actively assessed over complete follow-up. The study was terminated, and the primary outcome data were not collected; the record does not explain the safety follow-up procedures or duration for these group entries.

In general, a zero event count in a small study cannot rule out uncommon harms. Here, the recorded enrollment was 4, and the group-level safety counts are limited. The registry does not provide detailed event terms; no serious-event terms are listed. It also does not report a statistical comparison of safety between graft approaches. The counts therefore describe what was entered in the registry, but they do not establish that the approaches have equivalent safety or allow precise estimates of event risk.

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

The registry documents a planned randomized, double-masked, split-mouth comparison of two graft approaches for sinus augmentation. Bone Graft A combined small- and large-particle cortical and cancellous allograft, while Bone Graft B used 100% large-particle cancellous allograft. The primary outcome was intended to assess vital bone formation and inflammatory tissue, and Bone Volume Stability was listed as a secondary outcome.

The main result is that the primary data were not collected. There is no reported estimate of the difference in bone quality between approaches, no uncertainty interval, and no statistical test. The registry therefore cannot establish the direction, magnitude, or precision of a comparative effect. It also cannot establish that the approaches are equivalent or that one is superior.

The design might have enabled within-participant comparisons, but design intent is not an outcome result. Without reported paired measurements and an analysis, the potential statistical advantages of a split-mouth study cannot be assessed. The recorded enrollment of 4 does not by itself reveal how many outcome observations were obtained; the registry specifically says that data were not collected.

The safety counts list no serious or other adverse events and no deaths in either group record. Given the study’s early termination and limited recorded enrollment, these counts do not provide a precise or comprehensive comparison of safety. Likewise, the stated planning assumptions do not turn absent outcome data into a trial finding or observed power. The appropriate interpretation is that the registry records the study design, termination, and event counts, but does not provide comparative efficacy results for the primary outcome.

13. Why This Trial Matters Statistically

This trial is statistically notable because its design aimed to compare graft materials within a split-mouth framework, while its registry record reports no collected primary-outcome data. The contrast between a potentially informative paired design and the absence of outcome measurements illustrates a basic point: a design can specify a meaningful comparison, but statistical conclusions still require observed data and an analysis suited to the design.

Within-participant comparisons can, in general, reduce the influence of characteristics shared by sites in the same person. They also require correct handling of the pairing. The registry’s randomized, double-masked, split-mouth and crossover labels indicate the intended structure, but the record does not explain allocation procedures or report any fitted analysis. Readers therefore cannot assess how the design was implemented or whether the planned comparison preserved the paired information.

The study also illustrates why endpoints, time points, missing-data plans, and multiplicity procedures matter. The primary outcome included more than one tissue measure and listed multiple assessment times; the registry does not report how those components would have been analyzed together. Since data were not collected, even a clearly specified analysis plan would not yield an effect estimate. Here, the analysis plan itself is not reported in the registry record.

Finally, early termination and the small recorded enrollment limit what can be inferred from the safety counts and planning assumptions. The record is informative about the intended research question and why no primary outcome result is available, but it cannot resolve the comparative question statistically. That distinction is important when reading a registry entry: study design and outcome evidence are not the same thing.

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 most consequential limitation is that the registry explicitly states that primary-outcome data were not collected. No estimates are reported for percent vital bone formation or percent inflammatory tissue, so there is no direct statistical evidence addressing the primary comparison. The record gives no outcome values, confidence intervals, p-values, or analysis results.

The study is marked terminated, and the registry explains that the original principal investigator was no longer at the institution and that the sponsor and current principal investigator decided to close enrollment and terminate the study early. It does not report further detail about the timing of that decision, participant progress, or reasons beyond this statement. The recorded enrollment is 4, but the registry does not specify the number with completed procedures, available paired outcomes, or follow-up at each assessment time.

Although the study is described as randomized, double-masked, split-mouth, and crossover, the registry does not report allocation procedures, masking details, side assignment, or the sequence of graft application. It also does not provide a statistical analysis plan, the intended analysis population, handling of missing data, a multiplicity strategy, interim-analysis procedures, or the sample-size justification. These omissions prevent assessment of whether the planned statistical methods matched the design and outcomes.

The registry lists Bone Volume Stability and describes radiographs for estimating volume differences, but does not post those results. The safety counts are limited and do not establish comparative safety. Consequently, neither the primary question nor the secondary volume question can be answered from the reported analyses.

15. Related Tutorials

16. Related Statistical Calculators

17. Sources

• ClinicalTrials.gov: Bone Graft Particle Size on Bone Vitality and Volume — NCT04778709.
• Registry record last updated 2023-12-01; status last verified 2023-11.
• Results first posted 2023-12-01.
• 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

NCT04778709 is a randomized, double-masked, split-mouth study of graft particle size in sinus augmentation for dental implant placement. It compared a mixed-particle cortical and cancellous allograft approach with 100% large-particle cancellous allograft. The registry records enrollment of 4, a start date of 2020-11-13, a primary completion date of 2022-02-01, and terminated status.

The primary outcome, Quality of Bone, was intended to measure percent vital bone formation and percent inflammatory tissue, if any, after surgery, 8 months, and 1 year. The registry states that data were not collected and reports 0 analyses. It lists Bone Volume Stability as a secondary outcome. The recorded adverse-event entries list no serious events, other events, or deaths in either group. Because there are no primary outcome data or analyses, the registry does not provide an estimate of the comparative effect of the graft approaches.