In Vivo Assessment of the Tooth-Resin Composite Interface Using Optical Coherence Tomography: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for In Vivo Assessment of the Tooth-Resin Composite Interface Using Optical Coherence Tomography (NCT05145322), a randomized na study. The primary outcome is Marginal Staining: World Dental Federation (FDI) Criteria - Baseline.

2. Clinical Question

3. Trial Design

The registry describes a randomized, double-masked, parallel-group study sponsored by the University of Minnesota. It is marked completed, with enrollment of 36. The recorded start date is 2021-09-23, and the primary completion date is 2024-10-16. The phase is listed as NA.

Participants were assigned to one of two cavity preparation approaches. Group 1 used a lesion-specific cavity design with a 90 degree cavosurface angle throughout the cavity margins. Group 2 used a lesion-specific design with a wide bevel throughout the cavity margins. Both interventions are recorded as devices. The registry does not describe the masking procedures or the allocation sequence beyond identifying the trial as double-masked and randomized.

The stated study aim is to compare short-term marginal integrity using the FDI World Dental Federation and US Public Health Service assessment criteria, and to assess marginal integrity with OCT. The registry also lists OCT-related secondary outcomes concerning backscattered intensity at the occlusal cavosurface angle, tooth-resin interface gap at that angle, and backscattered intensity along the superficial 2mm depth of the preparation walls.

The primary outcome entry is specifically baseline marginal staining using FDI criteria. Although the registry lists 15 outcome measures, it does not report a single primary-outcome comparison across the categories or time points, and it lists 0 analyses. The detailed protocol, randomization method, masking implementation, and planned analysis methods 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.

Before assignment: Upon referral from the dental clinic or enquiries, potential participants were invited to attend a telemeeting where the participants were presented with the information of the trial using a MS Powerpoint slide deck. 46 participants were invited to the telemeeting and also attended an in-person screening session to determine whether they meet the inclusion criteria of the study. 36 met the inclusion criteria and were successfully enrolled into the study.

Overall Study

Reasons for not completing this period:

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 Marginal Staining: World Dental Federation (FDI) Criteria - Baseline, measured over Baseline.

The recorded primary endpoint is marginal staining assessed at baseline with the World Dental Federation (FDI) criteria. It is reported as a participant-level score. The registry describes the FDI criteria as a 5-point ordinal scale: 1 means no marginal staining; 2, minor staining that is easily removable by polishing; 3, moderate staining that is not esthetically unacceptable; 4, pronounced staining for which major intervention is necessary for improvement; and 5, deep staining that is not accessible for intervention.

An ordinal scale ranks categories, but the distance between adjacent scores is not necessarily equal. The categories describe increasing degrees of marginal staining rather than measurements on a continuous scale. The registry says that the outcome will be reported as a single score at baseline. It does not report the observed scores, a summary by group, or a follow-up comparison for this primary outcome.

Assessing marginal staining is relevant to the stated interest in restoration margins and their integrity. However, a baseline score alone does not show how staining changes after restoration or whether the preparation techniques differ over time. The study aim also names the US Public Health Service criteria and OCT, but the baseline FDI entry is the primary outcome recorded in the registry. The role of that baseline measure in any later analysis is not reported in the registry record.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

The registry identifies the study as randomized, double-masked, and parallel-group. In general, randomization is intended to reduce systematic differences in participant characteristics between assigned groups, while masking is intended to limit influences on care or assessment. A parallel design compares groups assigned to different approaches over the study period rather than describing a crossover. The registry does not report how randomization or masking was implemented, which people were masked, or whether masking was maintained.

How should an ordinal endpoint be understood?

In general, an ordinal outcome places observations into ordered categories. The FDI marginal staining scale has 5 ordered levels, with definitions ranging from no marginal staining to deep staining that is not accessible for intervention. The ordering conveys severity, but does not establish that the step from one category to the next represents the same amount of change throughout the scale. Statistical methods for ordinal outcomes can use that ordering, whereas a simple mean may impose assumptions about the spacing between scores. The registry does not report which summary or statistical method was planned or used.

The primary outcome is identified as a single score at baseline. A baseline measure describes the recorded status at that assessment; on its own, it is not a change score and does not give a treatment contrast over follow-up. The registry does not report the distribution of baseline scores by group, later FDI scores, or a method for comparing scores across time. It also does not report whether the baseline endpoint was intended as a descriptive measure or as part of a subsequent analysis.

What does a comparison estimate require?

In general, a group comparison needs a defined outcome summary, a contrast between groups, and an uncertainty measure if precision is to be assessed. A confidence interval gives a range of values compatible with the data and the statistical assumptions used for estimation; it is not a guarantee that the true effect lies within that range. A p-value addresses compatibility between the data and a specified null model, rather than measuring the probability that a treatment effect is true. No primary-outcome estimate, confidence interval, or p-value is reported in the registry record, so these concepts cannot be applied to a trial-specific primary result.

The registry names FDI and US Public Health Service visual assessments and OCT as approaches to examining marginal integrity. The listed OCT secondary outcomes include backscattered intensity at the occlusal cavosurface angle, tooth-resin interface gap at the occlusal cavosurface angle, and backscattered intensity along the superficial 2mm depth of the preparation walls. These outcome labels identify measurement topics, but not their scale, distribution, assessment procedure, or results. Those details and any comparison methods are not reported in the registry record.

Why are analysis details important?

In general, a statistical analysis plan specifies how outcomes will be summarized, which comparisons will be made, and how uncertainty and missing observations will be handled. A plan also helps distinguish prespecified analyses from exploratory ones. The registry lists 15 outcome measures and 0 analyses, and does not report a statistical analysis plan or identify a model for the primary endpoint. The choice of method cannot be inferred from the fact that the outcome is ordinal or that the study is randomized.

Multiple outcomes create a multiplicity issue in general: testing many outcomes or contrasts can increase the chance of at least one apparently unusual result under a null model. Methods to address multiplicity depend on which outcomes and comparisons were planned. The registry record does not report a multiplicity strategy, the hierarchy among the listed outcomes, or which results were intended to support a primary conclusion. It is therefore not possible to determine how any multiple comparisons were treated.

The record includes a sample-size assumption for a planning illustration based on an observed effect, with a two-sided significance level of 0.05, equal allocation, and a normal approximation. Such a planning illustration is not observed power and is not a trial result. The registry does not report the trial's own sample-size justification or the assumptions used in its design. Without a reported primary effect estimate, the planning illustration cannot substitute for a comparative analysis.

For the safety entries, the registry gives numbers at risk and event counts by group. Counts are descriptive; they do not by themselves show a comparative risk estimate or establish a causal relationship. General statistical interpretation of rare events also depends on the observation period and event definitions, details that are not reported in the registry record.

10. Multiplicity, Missing Data and Analysis Populations

The registry lists 15 outcome measures and 0 analyses. It describes the study aim as involving FDI and US Public Health Service visual assessment criteria and OCT, with several OCT-related secondary outcomes. The primary-outcome record is a baseline FDI marginal staining score, while the registry's note says that the primary outcome has several categories or time points and was not reduced to one comparison. Thus, the record does not define a single reported primary contrast to interpret.

In general, multiplicity arises when several outcomes, time points, or contrasts are examined. Without a prespecified hierarchy or adjustment strategy, selective emphasis on one result can make the overall evidence harder to interpret. No multiplicity approach, outcome hierarchy, or primary analysis specification is reported in the registry record. The listing of multiple measures alone does not establish which were formally tested.

Missing-data methods and the handling of withdrawals or incomplete assessments are not reported in the registry record. The analysis population is also not reported: the record does not say whether analyses used all randomized participants, participants with available measurements, or another defined group. The enrollment count does not resolve those questions. No assumptions about missing observations or exclusions should be inferred from the design description or the completion status.

In general, these details matter because choices about which observations enter an analysis and how missing values are handled can affect both the estimated effect and its uncertainty. The absence of these details limits appraisal of any comparative result; in this record, a primary-outcome comparison is not reported in the first place.

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 5% reporting threshold.

Most frequent non-serious adverse event terms

The registry lists 18 participants at risk for serious adverse events in Group 1 and 18 in Group 2. The serious adverse event count is 0 in each group. It also lists 18 participants at risk for other adverse events in each group, with counts of 1 in Group 1 and 2 in Group 2. Deaths are listed as 0 in both groups, and no top serious-event terms are listed.

These are recorded counts, not comparative estimates. They do not provide a confidence interval, a statistical test, or information about the timing or duration of event monitoring. The registry record does not explain event definitions or whether events were assessed as related to a preparation technique. The other adverse-event counts should not be interpreted as evidence of causation, nor should the absence of a recorded serious event be taken to establish that serious events could not occur.

Safety counts address a different question from the primary endpoint, which concerns baseline marginal staining. They do not indicate whether either preparation technique produced better marginal integrity. Interpretation is limited to the counts and group-specific numbers at risk recorded in the registry.

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

The registry record allows readers to identify the comparison of interest: a lesion-specific cavity design with a 90 degree cavosurface angle versus a lesion-specific design with a wide bevel, both for Class I composite restorations. It also identifies randomization, double masking, a parallel design, enrollment of 36, and a completed status. The stated study aim is to assess short-term marginal integrity through visual criteria and OCT.

What the posted record does not establish is whether the approaches differ on the primary outcome. The primary outcome is defined as baseline FDI marginal staining, but no group-specific outcome values or primary comparison are reported. An outcome definition is not a result. Similarly, the names of OCT secondary outcomes do not provide OCT measurements, estimated effects, or their precision. The record therefore cannot support a conclusion about the direction, size, or clinical importance of a difference in marginal integrity.

The safety counts show that the registry recorded no serious adverse events and no deaths in either group, alongside other adverse-event counts of 1 and 2. These entries are descriptive and do not establish a causal relationship or a difference in safety between approaches. They also do not answer the primary question about marginal staining or integrity.

In general, evidence about a treatment comparison requires both an estimate and information about uncertainty, interpreted in light of the outcome and study design. Neither the trial's completion status nor its randomized design supplies a missing outcome estimate. The absence of reported results in this registry record should not be mistaken for evidence of equal outcomes, no effect, or a particular direction of effect. It means that the comparative result cannot be assessed from the registry information recorded in this entry.

13. Why This Trial Matters Statistically

This trial is statistically notable for the distinction between its stated study aim and its registered primary outcome. The aim concerns short-term marginal integrity assessed with visual criteria and OCT, while the primary outcome entry identifies baseline FDI marginal staining. These are related to the same broad clinical topic, but a baseline score alone does not answer whether the preparation approaches differ over time. Clear alignment between a study question, a defined endpoint, and a reported comparison is essential to interpret a clinical trial.

The FDI measure is ordinal, with category descriptions that run from no staining to deep staining not accessible for intervention. This creates an important analytical choice: an analysis should respect the ordered categories without assuming that every step has equal distance. The registry does not identify the chosen method. That absence makes the outcome definition useful for understanding measurement, but insufficient for reproducing or evaluating a statistical comparison.

The record also lists multiple outcome measures, including visual assessments and OCT measures. In general, multiple outcomes make it important to clarify which result is primary and how multiplicity is handled. The registry lists 0 analyses and does not report a multiplicity strategy. As a result, readers cannot identify an inferential framework or determine how the stated outcomes were intended to contribute to a primary conclusion.

Finally, the recorded safety counts illustrate the difference between descriptive data and a comparative analysis. Counts can describe what was recorded in each group, but without an estimated contrast and its uncertainty they do not establish a difference. A randomized design is valuable for comparison, but a design label cannot replace transparent outcome reporting. For this trial, the registry's outcome definitions and design details can be described, while its primary comparative result remains unreported.

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 trial-specific limitation for statistical interpretation is that the registry does not report the primary-outcome comparison. The recorded endpoint is baseline marginal staining on the FDI criteria, described as a single score, but no group summaries, effect estimate, uncertainty interval, or test result is provided. The registry also notes that the primary outcome has several categories or time points and was not reduced to one comparison. Without a defined reported contrast, the primary question cannot be evaluated from the record.

The stated aim includes short-term marginal integrity, visual assessment with FDI and US Public Health Service criteria, and OCT. The available outcome descriptions include baseline FDI and named OCT measures, but not their observed results, assessment schedule beyond the stated baseline, or statistical handling. The record does not explain how baseline scores relate to any later assessment or which measure would anchor a primary comparison.

Although the trial is described as randomized and double-masked, details of sequence generation, allocation concealment, masking procedures, and maintenance of masking are not reported in the registry record. The record does not report participant characteristics, eligibility criteria, or the analysis population. It also does not describe missing-data handling, the statistical analysis plan, or a multiplicity strategy. These omissions limit evaluation of bias, precision, and reproducibility.

The registry lists 15 outcome measures but 0 analyses. That information does not explain whether analyses were performed outside the registry or how any results were selected for reporting. Safety counts are available, but event definitions and monitoring details are not reported. These limitations concern what can be interpreted from the registry record; they do not establish that the unreported procedures or analyses were absent.

15. Related Tutorials

16. Related Statistical Calculators

17. Sources

• ClinicalTrials.gov: In Vivo Assessment of the Tooth-Resin Composite Interface Using Optical Coherence Tomography — NCT05145322.
• Registry record last updated 2024-10-28; status last verified 2024-10.
• Results first posted 2024-10-28.
• 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

This completed, randomized, double-masked, parallel-group study sponsored by the University of Minnesota enrolled 36. It compared Class I composite restorations using a lesion-specific cavity design with a 90 degree cavosurface angle against a design with a wide bevel throughout the cavity margins. The recorded start date is 2021-09-23 and the primary completion date is 2024-10-16.

The stated aim concerns short-term marginal integrity assessed by FDI and US Public Health Service visual criteria and OCT. The primary outcome entry is baseline marginal staining on the FDI 5-point ordinal scale. The registry lists OCT secondary outcomes, 15 outcome measures, and 0 analyses, but does not report a primary-outcome comparison or OCT results.

The safety record lists 0 serious adverse events and 0 deaths in each group. Other adverse-event counts are 1 in Group 1 and 2 in Group 2. The statistical analysis plan, missing-data methods, analysis population, and multiplicity approach are not reported in the registry record.