Evaluation of Healing at Molar Extraction Sites With and Without Ridge Preservation: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for Evaluation of Healing at Molar Extraction Sites With and Without Ridge Preservation (NCT02543398), a randomized na study. The primary outcome is Radiographic Bone Changes.

2. Clinical Question

This is a question about anatomical changes at posterior extraction sites, rather than a reported comparison of later implant success or patient-centered outcomes. The registry background notes that ridge preservation has been proposed to limit dimensional changes after extraction and that clinical guidance for posterior sites was not established in the study description. The record therefore frames the comparison as an investigation of whether the measured tissue dimensions differ between the two approaches. It does not report a numerical result, an estimated treatment effect, or an analysis of the measured changes. The primary outcome includes both width and height and refers to measurements at more than one time point; the registry record does not reduce these components to one comparison.

3. Trial Design

NCT02543398 is a completed randomized, parallel-group trial. The registry lists no masking. The study was sponsored by The University of Texas Health Science Center at San Antonio, and the phase is listed as NA. Enrollment is recorded as 52. The registry dates the study start to 2013-10 and primary completion to 2016-05.

The two approaches were ridge preservation and no ridge preservation. In the preservation arm, the molar socket was grafted with a bone graft material derived from human donors and covered with a membrane. In the comparison arm, the socket was left to heal spontaneously without grafting material or a membrane. The description does not report how participants were assigned to the two arms, whether allocation was concealed, or whether the groups were intended to be equal in size. Per-arm enrollment counts are not reported in the registry record.

Randomization is intended, in general, to make treatment groups comparable on average with respect to measured and unmeasured characteristics. It does not guarantee that groups will be identical, especially in a trial with a modest enrollment. The parallel design means the assigned approaches are compared across groups rather than by assigning both approaches to the same participant. Because masking is listed as none, the record does not indicate that participants or study personnel were blinded to the assigned procedure. Whether image assessors were masked is not reported in the registry record.

The registry marks the trial as completed, but completion is not itself evidence that the planned outcome was reported or that the comparison showed a particular result. The number of outcome measures is listed as one, while the primary measure describes both ridge width and height across the initial and follow-up images. The record lists no analysis entries. It does not report a protocol, a detailed allocation procedure, eligibility criteria, or a statistical analysis plan.

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

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 Radiographic Bone Changes, measured over 3 months after tooth extraction.

The primary outcome is titled Radiographic Bone Changes. It concerns the width and height of the alveolar ridge, measured in millimeters from Cone Beam CT images. The first measurement is described as the initial image following tooth extraction; the later image is taken before implant placement, described as 3 months after extraction. The registry specifies a mean as the summary parameter and standard error as the dispersion measure.

These measurements are used to describe dimensional change in the bony ridge after extraction. In general, ridge dimensions can be relevant to planning subsequent implant placement, which is the rationale stated in the registry description. The images provide a way to quantify anatomical dimensions rather than relying only on a clinical impression. A mean summarizes the central value across observations, while a standard error describes the uncertainty in estimating that mean; it is not the same as the spread of individual measurements.

The outcome description includes two dimensions and measurements at two time points. The registry record does not state a single prespecified contrast, such as whether the primary comparison is a change score, a follow-up value adjusted for the initial value, or separate estimates for width and height. It also does not report numerical means, standard errors, confidence intervals, or a test result. The listed outcome is therefore interpretable as the intended measurement target, but the record does not provide an effect estimate to interpret.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

What does randomization contribute?

Randomization assigns participants to study approaches using a chance-based process. In general, its purpose is to reduce systematic differences between groups, so that an observed group contrast can be interpreted more plausibly as associated with the assigned approach. Randomization does not ensure that every characteristic is balanced in the realized groups, and it does not prevent bias from missing outcomes, deviations from assigned care, or selective reporting. The registry identifies the trial as randomized, but the allocation sequence method, concealment procedure, and any stratification factors are not reported in the registry record.

What does a parallel design mean?

In a parallel design, participants are assigned to one of the compared approaches and the groups are followed over the study period. The registry lists this trial as parallel. In general, the comparison is between outcomes in the assigned groups, rather than a within-person comparison of both procedures. A clear analysis would specify which participants are included, which outcome measurement is compared, and how the two CT time points contribute to the estimate. Those analysis details are not reported in the registry record.

How should the endpoint summary be understood?

The outcome is continuous: ridge width and height are recorded in millimeters. The registry identifies the mean as the summary parameter and the standard error as the dispersion measure. A mean represents the average measurement in a group. A standard error describes the statistical uncertainty around an estimated mean and generally becomes smaller when estimates are based on more information and observations are less variable. It does not describe the range of individual measurements; a standard deviation is commonly used for that purpose. The registry does not report observed means, standard errors, or standard deviations.

The outcome description includes an initial image and a later image. A comparison could be framed as the difference in follow-up means, the mean change within each group followed by a contrast between groups, or a model that adjusts follow-up measurements for initial measurements. These approaches answer related but not identical questions and can have different precision. The record does not state which approach was planned or used. Because both width and height are named, the intended handling of those outcomes also needs clarification; no combined endpoint or hierarchy is reported.

What do confidence intervals and tests tell a reader?

In general, a confidence interval gives a range of effect estimates that are compatible with the data and the assumptions of the chosen statistical method. Its width communicates precision: a wider interval indicates less precise estimation than a narrower one. The interval should be interpreted alongside the effect estimate and the clinical context, not as a simple pass-or-fail rule. A hypothesis test and its p-value address compatibility with a null hypothesis under a model. A p-value does not measure the probability that the null hypothesis is true, nor does it describe the size of an effect.

No estimate, confidence interval, or test result for the primary outcome appears in the registry record. It is not possible to apply these interpretive tools to the intended bone measurements. If those values become available, readers would need to check that the contrast, units, and analysis population are clearly stated and that uncertainty is reported for each outcome of interest.

Why can over-dispersion matter?

In general, over-dispersion occurs when observed variability is greater than a statistical model assumes. It can make standard errors too small and confidence intervals too narrow if the model does not account for the extra variability. That issue is particularly relevant for outcomes whose variance structure differs from the assumptions of a simple model, such as counts with variability beyond a basic count distribution. The primary endpoint in this trial is described as a continuous measurement, and the registry does not report an analysis model or evidence of over-dispersion. It would be inappropriate to assert that over-dispersion occurred or that any particular correction was used.

What do the planning assumptions mean?

The record describes a planning illustration using a two-sided significance level of 0.05, equal allocation between arms, and a normal approximation. It says the effect to detect is a stated fraction of the observed effect, and distinguishes this calculation from the trial's own design. In general, such calculations explore how many participants per arm might be needed under stated assumptions. They depend on the assumed effect and variability, as well as the chosen error rate and target power. If the true effect is smaller than the assumed effect, more information is generally needed to detect it with the same target power. The planning output is not an observed result and is not observed power. The numerical planning illustrations and the trial's original sample-size justification are not reported in the registry record.

10. Multiplicity, Missing Data and Analysis Populations

The primary outcome description contains more than one measurement dimension and more than one time point. The registry notes that the primary outcome has several categories or time points and is not reduced to one comparison. It does not report how width and height are handled statistically, whether one is designated as primary, or whether a multiplicity adjustment is planned. When multiple outcomes or comparisons are tested, the chance of at least one apparently unusual result can increase; methods to address this depend on the analysis plan and the scientific priorities. No such plan is reported in the registry record.

Missing-data handling is also not reported in the registry record. There is no account of participants without a later CT image, incomplete measurements, reasons for missingness, or the method for handling any missing values. These details matter because estimates based only on observed measurements can be biased if missingness is related to outcomes or group assignment. The record also does not state whether an intention-to-treat population, a per-protocol population, or another analysis population was planned. The number of participants contributing to the primary outcome is not reported.

The registry lists no analysis entries. It does not report interim analyses, stopping rules, prespecified subgroup analyses, or sensitivity analyses. These are not assumed to have occurred or not occurred; they are not reported in the registry record. Without the prespecified analysis choices and participant flow, readers cannot assess whether the posted analysis follows an original plan or how robust an estimate might be to alternative assumptions.

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 safety listing records 20 participants at risk in the ridge preservation group and 20 in the no ridge preservation group. It records zero serious adverse events, zero other adverse events, and zero deaths in each group. These are the counts recorded in that listing; they are not results for the radiographic primary outcome.

A count of zero means that the registry lists no events of that category among the participants counted as at risk in that entry. It does not establish that an event is impossible, and it does not by itself characterize the precision of safety estimates. Rare events can be difficult to assess in small groups, and the registry record does not provide an accompanying confidence interval or further event detail.

The record does not report the safety observation period, the definitions used for serious and other adverse events, how events were collected, or whether the listed counts cover all enrolled participants. Enrollment is recorded as 52, while the safety listing gives the per-group at-risk counts stated above; these figures should not be combined or treated as a complete account of the primary-outcome population. The listed safety data should therefore be read narrowly as the event counts recorded in the registry, not as proof of overall safety.

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

The registry record describes a randomized comparison intended to measure radiographic changes in ridge width and height after molar extraction, with or without ridge preservation. The record establishes the study question, the two approaches, the planned imaging time points, and the broad trial design. It does not provide a numerical comparison of bone dimensions. As a result, it cannot show the direction or magnitude of any difference, or how precisely a difference was estimated.

The absence of a reported result is not evidence that the approaches produced the same outcomes. It is also not evidence that they produced different outcomes. Both conclusions require an estimate based on outcome data and an account of its uncertainty. Because the record does not report those analyses, neither a positive nor a null conclusion about radiographic change can be drawn from it.

The study description connects ridge dimensions with prospective implant placement, but the listed primary outcome is anatomical measurement. The record does not report implant placement success, patient experience, or a separate soft-tissue result. Conclusions about those outcomes would go beyond the outcomes and analyses recorded. Likewise, the safety listing gives event counts but does not provide enough detail to support a broad conclusion about safety across all participants or over a defined observation period.

In general, statistical evidence is most informative when it includes the estimated effect, its uncertainty, a clear definition of the comparison, and the population analyzed. Those elements are not reported for the primary outcome in the registry record. The appropriate interpretation is therefore limited: this completed trial was designed to address a relevant question about healing after molar extraction, but the registry record does not present the outcome analyses needed to answer it.

13. Why This Trial Matters Statistically

This trial addresses a design question that is specific to molar extraction sites. The registry description distinguishes posterior sites from the anterior-tooth context mentioned in its background and frames dimensional change as relevant to prospective implant placement. That makes the comparison statistically and clinically focused: the intended contrast is between grafting and membrane coverage versus spontaneous healing, with ridge dimensions assessed radiographically.

Its randomized parallel design is suitable in general for comparing two approaches, provided the allocation, follow-up, outcome measurement, and analysis are reported clearly. The endpoint also illustrates an important analysis issue: a study can list one primary outcome while describing multiple dimensions and measurement times. Prespecifying the principal contrast and explaining how each dimension is analyzed helps readers understand what claim the results are intended to support.

The record also shows why registration and posted results serve different purposes. Registration identifies the intended question and design; interpretation of effects requires outcome estimates, uncertainty, and details of the analysis population. Here, the registry lists no analysis entries and no numerical primary-outcome results. The design can therefore be understood, but the comparative evidence cannot be evaluated from the record.

Finally, planning calculations and observed results answer different questions. Planning illustrations are conditional on assumptions about effect size, allocation, and statistical methods. They do not replace observed effect estimates, and they do not establish that the trial could detect a clinically important difference. Keeping those distinctions clear is especially important when the result analysis and its precision are not reported.

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.

A key limitation of the available record is that it contains no numerical analysis of the primary outcome. It does not report group-specific ridge measurements, changes from the initial image, effect estimates, confidence intervals, or test results. The registry describes both width and height but does not specify which contrast was used or how the multiple dimensions and time points were handled.

Information about the study population is limited. The record concerns molar extraction and lists loss of teeth due to extraction as the condition, but eligibility criteria, baseline characteristics, extraction-site characteristics, and the distribution of relevant clinical factors are not reported in the registry record. Per-arm enrollment and the number contributing primary-outcome data are also not reported. The enrollment entry and safety-listing counts do not resolve those gaps.

Further design and conduct details are absent. The registry does not report the randomization method, allocation concealment, assessor masking, protocol deviations, missing-data handling, or the statistical analysis plan. Masking is listed as none, but whether image assessors were masked is not reported. The intervention description gives the broad graft-and-membrane approach, while fuller procedural details are not reported in the registry record.

Safety information is limited to event counts without definitions, observation period, or uncertainty estimates. The record also does not report outcomes beyond the listed radiographic measure, such as later implant outcomes or patient-centered measures. These limitations concern what can be learned from this registry record; they do not establish that the trial failed to collect or analyze those data elsewhere.

15. Related Tutorials

16. Related Statistical Calculators

17. Sources

• ClinicalTrials.gov: Evaluation of Healing at Molar Extraction Sites With and Without Ridge Preservation — NCT02543398.
• Registry record last updated 2018-06-28; status last verified 2017-05.
• Results first posted 2017-11-01.
• 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

NCT02543398 is listed as a completed randomized, parallel-group trial with no masking. It enrolled 52 participants and compared ridge preservation after molar extraction with spontaneous healing without grafting or a membrane. The study was sponsored by The University of Texas Health Science Center at San Antonio. The start date is 2013-10, and primary completion is dated 2016-05.

The primary outcome is radiographic bone change, described as mean ridge width and height in millimeters measured on Cone Beam CT images after extraction and before implant placement, at 3 months after extraction. The record lists no analysis entries and does not report numerical primary-outcome results. Safety entries list zero serious adverse events, zero other adverse events, and zero deaths in each group, with 20 participants at risk in each group.

The registry record specifies the study question and broad design, but does not report the analysis needed to determine the size or precision of a difference in radiographic healing between the approaches.