Evaluation of Using Different Screwed Abutment Height: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for Evaluation of Using Different Screwed Abutment Height (NCT06017115), a randomized na study. The primary outcome is Marginal Bone Loss.

2. Clinical Question

The trial is identified as randomized, double-masked, and parallel-group. These labels indicate the registered design categories, but the registry record does not explain how the random sequence was generated, who was masked, or how masking was maintained. The record identifies bone loss as a condition and the trial as a prospective randomized controlled clinical trial.

The central clinical measurement is a radiographic bone-level measure rather than a direct measure of symptoms or quality of life. The registry also lists probing depth, bleeding on probing, and keratinized mucosa width as secondary outcomes. It does not provide values for these outcomes or specify which measure, if any, was used to make a formal comparison between treatment groups.

3. Trial Design

The registry identifies a randomized, double-masked, parallel-group clinical trial. It describes a prospective study comparing implant placement with a cover screw against placement with a definitive transepithelial abutment. The sponsor is Universitat Internacional de Catalunya. The trial status is completed. The recorded start date is 2017-07-01, and the recorded primary completion date is 2022-07-30.

The two approaches differed in the planned surgical sequence. In the control group, a cover screw was placed during the first surgery. The description says a second surgery would expose the implants and place a healing abutment after 2-4 months. In the test group, the definitive transepithelial abutment was placed on the day of implant placement, with a protective plastic cap. The registry characterizes this as a one-surgery approach. Further details about the treatment protocol, such as the exact abutment heights compared, are not reported in the registry record.

The recorded enrollment is 30. The primary-outcome description also reports that 30 patients with 60 implants were assessed after 24 months: 12 patients and 24 implants in the control group, and 18 patients and 36 implants in the test group. However, the test-arm description says “36 patients,” which conflicts with the primary-outcome description of 18 test-group patients. The registry record therefore contains an internal inconsistency in the test-group patient count; the outcome description gives 18 patients, while the arm description gives 36.

The listed primary endpoint is marginal bone loss, measured after implant loading as baseline and once every year to 24 months of follow-up. The registry states that the mean of mesial and distal measurements was calculated for each implant, followed by group-level means for mesial, distal, and total implant measurements. It does not report the actual means, standard deviations, or a single selected comparison. The record lists three secondary outcomes and four outcome measures overall. It does not provide a statistical analysis entry.

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: A total of 30 patients (60 implants), 12 of the control group (24 implants) and 18 of the test group (36 implants) were assessed after 24 months follow-up.

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: A total of 30 patients (12 of the control group and 18 of the test group) started the study and complete the 24 months of follow-up.

6. Primary Endpoint

The registry lists the primary outcome as Marginal Bone Loss, measured over After implant loading (baseline)and once every year to 24 months follow-up.

The primary endpoint is marginal bone loss, measured in millimeters. The description defines the measurement as the distance from the implant platform to the first bone-to-implant contact on an intra-oral radiograph. Measurements were taken at two points, mesial and distal, and the two-point mean was calculated for each implant. Group-level means were then described for mesial, distal, and total implant measurements.

Bone level is used in this trial as a radiographic measure of the peri-implant bone response. Measuring it over follow-up can describe how the recorded bone level changes relative to the implant platform. The registry identifies the period after implant loading as baseline and says measurements were scheduled once every year to 24 months of follow-up. It does not explain how baseline values were incorporated into the analysis, or which follow-up time point was designated for a single primary comparison.

Means summarize the average measurement in a group, while standard deviations describe how dispersed individual measurements are around that average. These are general statistical interpretations of the mean and standard deviation; the registry lists these summary measures but does not report their numerical values. Because each patient could contribute more than one implant, measurements from implants belonging to the same patient may be related. Whether the analysis accounted for this within-patient relationship is not reported in the registry record.

The registry does not report outcome values, confidence intervals, or a statistical test for the primary endpoint. Consequently, the endpoint definition is available, but the direction, size, and precision of any observed difference between approaches cannot be assessed from the registry record.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

The registry classifies the study as randomized, double-masked, and parallel-group. These design terms have general statistical meanings, but the details behind them are not reported in the registry record.

What does randomization contribute?

In general, random allocation is intended to make treatment assignment independent of participants’ measured and unmeasured characteristics, on average. This can reduce systematic differences between groups that might otherwise influence the outcome. Randomization does not guarantee that the groups will be identical, especially in a trial of this size, and it does not prevent bias from missing outcomes, measurement differences, or departures from assigned treatment. The registry does not describe the random-sequence method, allocation concealment, or whether assignment used any stratification or blocking.

What does double masking mean?

Masking is intended to limit the influence of treatment knowledge on care, outcome assessment, or reporting. The registry labels the trial double-masked, but does not say which people were masked or how masking was implemented. Because the two approaches involve different surgical sequences, the practical masking procedures and their success cannot be assessed from the record.

How should the endpoint summaries be understood?

The endpoint is a continuous measure in millimeters, summarized as a mean with standard deviation. In general, a mean represents the average measurement, while a standard deviation describes variability among measurements. The standard deviation is not a measure of uncertainty in the mean. A confidence interval for a mean or for a between-group contrast would address estimation precision; no confidence interval is reported for this endpoint.

The registry describes two radiographic measurements per implant, at mesial and distal points, and says that their mean was calculated for each implant. It then describes group means for mesial, distal, and total implant measurements. It does not specify which of these summaries was the primary comparison or whether the repeated measurements over time were analyzed as change from baseline, as values at each time point, or by another approach.

Why does the patient and implant distinction matter?

The outcome description reports 60 implants among 30 patients. When more than one implant is measured in a patient, those measurements may be correlated because they share patient-level characteristics. In general, treating correlated measurements as if they were independent can make uncertainty estimates too narrow. Methods such as patient-level summaries or models that account for clustering can address this issue, depending on the study design and analysis objective. The registry does not report whether the analysis accounted for the relationship between implants from the same patient.

Repeated measurements at baseline and follow-up also raise an analysis choice. In general, investigators may compare follow-up values, model changes from baseline, or use a repeated-measures approach. These approaches answer related but not identical questions and can rely on different assumptions. The registered description gives the follow-up schedule but does not report which method was used, how correlations across time were handled, or whether any adjustment variables were included.

What is not available about the statistical analysis?

The registry contains no analysis entries and no numerical primary-outcome results. It does not report a statistical model, test statistic, p-value, confidence interval, or adjustment for potential covariates. The sample-size planning details for the trial, including any original assumptions or justification, are not reported in the registry record. A separate planning illustration based on an observed effect would not establish the trial’s original design rationale or observed power.

In general, statistical significance and clinical importance are distinct ideas. A p-value, when reported, addresses how compatible the data are with a specified statistical model and null hypothesis; it does not by itself quantify the size or practical importance of an effect. An effect estimate and its confidence interval are needed to examine magnitude and precision. Because neither is reported, statistical significance and effect magnitude cannot be evaluated for this trial from the registry record.

Finally, the registry identifies multiple outcome measures and multiple time points for marginal bone loss, but does not report a multiplicity strategy. In general, testing several outcomes or time points can increase the chance of a false-positive finding if all tests are treated as confirmatory without adjustment. Whether any adjustment or prioritization was planned or used is not reported. These missing details limit assessment of the analysis, but they do not establish that a particular method was or was not used outside the registry record.

10. Multiplicity, Missing Data and Analysis Populations

The registry lists four outcome measures overall and identifies marginal bone loss as the primary outcome. It also names probing depth, bleeding on probing, and keratinized mucosa width as secondary outcomes. The primary outcome is described across several measurement locations and time points, with follow-up after loading as baseline and once every year to 24 months. The record does not identify a single reported comparison across those locations or time points, and it contains no analysis entries.

Multiplicity is a general statistical concern when several outcomes, time points, or comparisons are tested. Without a prespecified hierarchy or adjustment, the chance of at least one nominally positive result can increase as the number of tests grows. The registry does not report whether the investigators used a multiplicity adjustment, selected one primary time point, or designated particular outcome summaries as confirmatory. It would be inappropriate to assume either that adjustment was made or that all listed measures were tested.

Missing-data methods and outcome completeness are not reported in the registry record. The primary-outcome description says 30 patients were assessed after 24 months, but does not state whether measurements were available for every participant, every implant, or every scheduled time point. It does not describe reasons for missing observations, imputation, sensitivity analyses, or a missing-data assumption.

Analysis populations are also not specified. The record does not say whether results were analyzed according to randomized assignment, treatment received, or another population definition. The reported inconsistency between the test-arm description and the primary-outcome population adds uncertainty about how the enrolled and analyzed groups were recorded. These omissions prevent assessment of how incomplete follow-up and multiple outcome comparisons may have affected the reported analysis.

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’s adverse-event entries report zero serious adverse events and zero deaths in the control group, with 12 participants listed as at risk. For the test group, it reports zero serious adverse events and zero deaths, with 18 participants listed as at risk. The record also reports zero other adverse events in each group, using the same at-risk group counts. No serious adverse-event terms are listed.

These entries describe what is recorded in the registry, not proof that no adverse events occurred in any broader sense. The registry does not explain the adverse-event collection period, definitions, ascertainment procedures, or whether the figures reflect complete follow-up for every participant. It also does not provide event narratives or separate results by implant.

Zero events in the listed entries should not be interpreted as demonstrating equal safety between approaches. In general, when no events are recorded, the data still leave uncertainty about event rates, particularly when the number of people observed is limited. A comparative safety estimate and its precision are not reported in the registry record. The adverse-event entries therefore provide a limited count-based account and do not support a broader safety conclusion.

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

The record establishes that a randomized, double-masked, parallel-group trial compared a cover-screw approach with placement of a definitive transepithelial abutment on the day of implant placement. It identifies marginal bone loss as the primary outcome and describes the radiographic measurement. It also records a 24-month assessment and names three secondary outcomes.

What the record does not establish is the observed marginal bone loss in either group or the size and precision of any between-group contrast. No means, standard deviations, confidence intervals, or statistical tests are reported for the primary endpoint. Therefore, the registry record cannot show whether the groups had similar or different measurements, or whether any difference favored either approach. It also cannot establish the results for the listed secondary outcomes.

In general, a trial’s design and endpoint definition describe how a question was to be studied; they are not substitutes for the outcome data. A completed status indicates the registry lists the trial as completed, but does not reveal the direction or reliability of its findings. Similarly, randomization describes an allocation method, not a guarantee that all sources of bias or uncertainty have been eliminated.

The adverse-event entries report zero events in the listed categories for both groups, but their scope and collection details are not reported. These counts should be interpreted as registry entries rather than as definitive evidence about all possible safety outcomes.

The record also contains inconsistent test-group patient counts: the primary-outcome description says 18 test-group patients, whereas the test-arm description says 36 patients. The latter number matches the primary description’s count of test-group implants, but the registry does not clarify the discrepancy. Thus, the participant accounting is not fully consistent within the record. Overall, the available information supports an understanding of the trial question, design, and intended measurement, but not an assessment of comparative effect or statistical uncertainty.

13. Why This Trial Matters Statistically

This trial raises several important statistical issues that are common in clinical studies with continuous outcomes and multiple measurements. The primary endpoint is measured on implants, while the population is described in patients. Because the record reports multiple implants per patient, it matters whether the analysis recognizes that measurements from one person may be related. The registry does not report how this issue was handled.

The outcome was measured at two radiographic locations and across follow-up. Such repeated measurements can be summarized in several ways, and the choice affects the precise question addressed by an analysis. The record gives the measurement process but does not identify a single primary contrast across time or locations, nor report how repeated observations were modeled. This limits interpretation even if a reader knows the endpoint’s general definition.

The record is also a useful reminder that a randomized design does not by itself provide evidence of an effect. Interpretation requires outcome estimates and measures of uncertainty, neither of which is reported for marginal bone loss. Without them, readers cannot judge the magnitude or precision of a group difference. The completed trial status and zero adverse-event entries do not fill that gap.

Finally, transparent participant accounting matters when reading trial results. The discrepancy between the test-arm description and the primary-outcome population illustrates why the numbers of patients and implants should be distinguished and reconciled. Here, the registry reports 18 test-group patients and 36 test-group implants in the primary-outcome description, but the arm description calls 36 patients. The record does not explain the mismatch. These design and reporting issues are statistically relevant because they affect the interpretation of the analysis population, the unit of analysis, and the precision that an analysis could support.

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 from the registry record is the absence of numerical outcome results. Marginal bone-loss means and standard deviations are not reported, and neither are effect estimates, confidence intervals, or p-values. The record therefore does not permit an assessment of the direction, size, or precision of a treatment-group contrast.

Several design and analysis details are also unavailable. The registry does not report the random-sequence method, allocation concealment, the people masked, or how masking was maintained. It does not give a statistical analysis plan, explain how repeated observations or multiple implants per patient were handled, or state whether any covariates were adjusted for. It also does not identify a single primary comparison among the described locations and time points.

There is an internal inconsistency in group accounting. The primary-outcome description reports 18 test-group patients and 36 test-group implants, while the test-arm description says 36 patients. The record does not resolve this discrepancy. It also does not report measurement completeness, missing-data handling, analysis populations, or reasons for any unavailable observations.

For safety, the registry lists zero serious and other adverse events in both groups and zero deaths, but does not explain ascertainment, follow-up windows, or event definitions. These reporting limits mean that the counts should be read narrowly. They do not permit a comprehensive comparative safety assessment.

15. Related Tutorials

16. Related Statistical Calculators

17. Sources

• ClinicalTrials.gov: Evaluation of Using Different Screwed Abutment Height — NCT06017115.
• Registry record last updated 2025-06-26; status last verified 2025-06.
• Results first posted 2025-06-26.
• 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

The registry identifies a completed randomized, double-masked, parallel-group trial sponsored by Universitat Internacional de Catalunya. It compares a cover-screw, two-stage approach with a one-surgery approach using a definitive transepithelial abutment. Recorded enrollment is 30; the primary-outcome description reports 30 patients and 60 implants assessed after 24 months.

Marginal bone loss, measured in millimeters from the implant platform to first bone-to-implant contact, is the primary outcome. The registry lists probing depth, bleeding on probing, and keratinized mucosa width as secondary outcomes. It does not report outcome values or statistical analyses. The test-group patient count is inconsistent between the arm and primary-outcome descriptions, and the record does not resolve the discrepancy.