Peri-implantitis Treatment: Clinical Results of Conventional Treatment vs. the Addition of Biolase: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for Peri-implantitis Treatment: Clinical Results of Conventional Treatment vs. the Addition of Biolase (NCT03544515), a randomized na study. The primary outcome is Change in Probing Depth (PD).

2. Clinical Question

The registry record describes the study as a pilot intended to explore possible differences between these approaches. Its stated research hypothesis was that adding active laser treatment could improve clinical parameters through removal of microbiota from a rough implant surface. That statement is the investigators’ hypothesis, not a finding established by the posted primary outcome.

3. Trial Design

The study is recorded as randomized, triple masked, and parallel-group. It enrolled 32 participants and is marked completed. The sponsor is Columbia University. The registry lists the start date as 2019-01-14 and the primary completion date as 2021-08-02. The phase is listed as NA, which is a registry classification rather than a description of the study’s statistical design.

Both groups received scaling and debridement with hand scalers and an ultrasonic unit. The distinguishing component was whether the Er,Cr:YSGG laser was applied actively or in an inactive fashion. The registry describes the active group as scaling and debridement together with active laser application, and the inactive group as the same conventional procedure with inactive laser application. This makes the contrast focused on the laser application under the described treatment conditions.

The primary outcome description says that probing depth was measured using a manual periodontal probe, with measurements at six sites per implant. It reports averages across sites and implants, with 26 implants in the inactive arm and 38 in the active arm. For the primary analysis, the record says that 10 of 16 subjects who completed the study in the inactive group and 13 of 15 who completed in the active group were analyzed. These are distinct counts: the record does not say that every subject who completed contributed to the primary analysis.

The registry does not report the number randomized to each arm, allocation procedures beyond the randomized designation, masking roles, eligibility criteria, or details of treatment delivery beyond the arm descriptions. The planned statistical analysis, sample-size justification, and handling of protocol deviations are also not reported in the registry record. The pilot designation and enrollment total alone do not establish what statistical precision or power the investigators intended.

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

Reasons for not completing this period:

Analysis population for the primary outcome, as defined in the registry: Analyzed 10 out of 16 subjects who completed the study in the control (inactive) group, and 13 out of 15 subjects who completed the study in the laser (active) group.

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 Change in Probing Depth (PD), measured over Baseline, 9 months.

The primary endpoint is change in probing depth (PD), measured in millimetres at baseline and 9 months. Probing depth is a clinical measurement taken with a periodontal probe. In this study, the record specifies a manual UNC-15 probe and six measurement sites per implant: mesio-buccal and lingual, mid-buccal and lingual, and disto-buccal and lingual. It says that the reported value is the average across sites for all implants in each arm.

Change in a continuous measurement can describe how the observed measurement differs between assessment times. Comparing the mean change between randomized groups is a way to assess whether the groups’ average trajectories differ, subject to the analysis and its assumptions. A group’s mean change on its own does not estimate the treatment contrast: the contrast depends on comparing the groups directly, with uncertainty for that difference.

Probing depth is used as a clinical measure relevant to peri-implant tissues. The registry record states the measurement method and timing, but does not provide a detailed rationale for selecting this endpoint or define a threshold for a clinically important change. It also does not state the subtraction order used to calculate change. The posted means are -0.73 mm for the inactive group and -1.36 mm for the active group; their interpretation should remain tied to the recorded definition and should not be treated as a direct treatment-effect estimate.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

Several statistical ideas help distinguish the reported arm summaries from the comparative question. The registry record does not describe the analysis methods used to generate the primary results, so the explanations below are general rather than claims about the investigators’ actual procedures.

What a mean change describes

A mean is a summary of a continuous measurement across the observations included in its calculation. A mean change summarizes the observed changes in that analysis population. In this trial, the endpoint description says that the average is based on probing-depth measurements across sites and implants. The arm means are -0.73 mm in the inactive group and -1.36 mm in the active group. The registry record does not state whether the average was calculated first within each subject and then across subjects, or whether another weighting scheme was used. That distinction can affect what a group mean represents when participants contribute different numbers of implants or measurements.

What a confidence interval describes

A confidence interval is a statistical expression of uncertainty around an estimate, under the assumptions of the method used to calculate it. It is not a guarantee that the true value lies within the reported limits, and it does not show the range of individual participants’ measurements. The registry reports a 95% confidence interval for each arm: -1.17 to 0.28 for the inactive group, and -1.96 to 0.77 for the active group. The record does not specify the interval method or model. Because the interval calculation is not described, its assumptions cannot be checked from the registry record.

Why the group contrast is different

The scientific comparison concerns the difference in mean change between the active and inactive groups. A direct contrast has its own estimate and uncertainty. Arm-specific estimates and their intervals are not a substitute for that contrast, and overlapping or non-overlapping arm intervals do not by themselves provide the formal comparative analysis. Here, the registry marks the continuous two-arm comparison as missing or not estimable. It gives no reported contrast, p-value, or analysis entry. No new contrast should be inferred from the arm summaries.

Repeated and clustered observations

General statistical methods must account for how observations are related. Measurements from several sites on the same implant, or from multiple implants belonging to the same subject, are not necessarily independent. Treating correlated observations as independent can make uncertainty estimates misleading. The registry describes six probing-depth sites per implant and reports implant counts that differ between arms. It does not state whether the analysis accounted for clustering within implants or subjects, or how site-level observations were combined. These details are important for understanding precision, but they are not reported in the registry record.

Planning calculations and observed results

The registry information describes a planning illustration based on the observed effect, with a two-sided significance level of 0.05, equal allocation, and a normal approximation. It says the planning target can be expressed as a stated fraction of the observed effect. Such calculations are prospective illustrations of the sample size that would be associated with specified assumptions; they are not observed power and do not change the evidence from the completed trial. No numeric planning results are reported in the record summarized for this analysis, and the trial’s own sample-size justification is not reported in the registry record. The assumptions used for an illustration should not be mistaken for the actual design rationale.

Over-dispersion and model choice

General count-data analyses may encounter over-dispersion, meaning the variation is greater than expected under a simple model. That issue can affect standard errors and confidence intervals. The primary outcome in this study is continuous, not a count, and the registry does not identify an over-dispersion model or any other fitted model. More broadly, model choice should match the type and structure of the outcome data. Because the analysis plan and model are not reported, it is not possible to determine whether the reported intervals reflect an appropriate structure for repeated measurements or clustered implants.

The record lists five secondary outcomes in addition to the primary outcome and reports six outcome measures overall. It does not describe how those outcomes were tested or whether any adjustment was planned for multiple comparisons. Statistical methods for missing observations, covariates, sensitivity analyses, or interim analyses are not reported in the registry record. These omissions limit reproducibility and make it difficult to connect the posted descriptive values to a prespecified inferential analysis.

10. Multiplicity, Missing Data and Analysis Populations

The registry lists five secondary outcomes alongside the primary endpoint, for six outcome measures overall. The secondary outcomes concern radiographic bone loss, bleeding on probing, suppuration on probing, plaque, and clinical attachment level or mobility. The record does not report whether each outcome was formally tested, which outcomes were included in a multiplicity strategy, or whether any adjustment to account for multiple comparisons was planned. Without that information, the extent to which the primary outcome was treated as the sole confirmatory test is not reported in the registry record.

Missing-data information is also limited. The primary endpoint description states that 10 of 16 subjects who completed in the inactive group and 13 of 15 who completed in the active group were analyzed. The reason the remaining completers were not included is not reported in the registry record. The record does not describe missing measurements at the site, implant, or subject level, nor does it state how missing outcome data were handled. It also does not give a comparison of included and excluded participants.

The analysis population is not described as intention-to-treat, per-protocol, or another prespecified population. The randomized participant counts by arm are not reported. These gaps prevent a full assessment of whether the posted analysis preserves the randomized comparison and how sensitive the result may be to missing observations. No imputation method, sensitivity analysis, or missing-data assumption is reported. These are uncertainties about the record, not evidence that a particular approach was or was not used.

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 reports serious adverse events, other adverse events, and deaths separately for the two listed groups. For the inactive-laser group, 10 participants are listed at risk for serious events and 10 at risk for other events; zero serious events, zero other events, and zero deaths are reported. For the active-laser group, 13 participants are listed at risk in each event category; zero serious events, zero other events, and zero deaths are reported.

These figures describe the posted counts in the stated risk groups. They do not establish that no events occurred outside the registry’s reporting scope, and the record does not give event definitions, ascertainment procedures, follow-up completeness, or detailed adverse-event terms. The registry lists no serious-event terms. A zero count in a limited risk set should not be interpreted as proof that an intervention has no safety risks, nor does it support a comparison of safety rates without additional context. The event counts are descriptive registry data, not a substitute for a comprehensive safety assessment.

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

The posted primary values show the mean change in probing depth within each analyzed group: -0.73 mm in the inactive-laser group and -1.36 mm in the active-laser group. The reported 95% confidence intervals are -1.17 to 0.28 and -1.96 to 0.77, respectively. These are arm-level summaries. The registry record does not report a direct estimate of the between-group difference, and it marks the continuous two-arm comparison as missing or not estimable.

As a result, the primary result does not quantify the comparative effect of active versus inactive laser application. It does not report the uncertainty around such a contrast, a p-value, or a conclusion from a stated inferential test. The arm means alone cannot answer whether the groups differ statistically or clinically. Nor can the listed intervals be treated as intervals for the difference between groups.

The results also do not establish the effect in all enrolled or randomized participants. The primary endpoint was analyzed in 10 of 16 subjects who completed in the inactive group and 13 of 15 who completed in the active group. Reasons for this analysis population, the missing-data approach, and the number randomized to each group are not reported in the registry record. The description of measurements across sites and implants also leaves open how clustering and unequal implant counts were handled.

The study’s stated hypothesis and pilot purpose provide context for why the comparison was undertaken, but a hypothesis is not a result. The posted values do not prove that either approach is effective or ineffective, and they do not support medical advice. They show only the reported arm-specific summaries and their listed intervals, with important comparative and methodological details unavailable in the registry record.

13. Why This Trial Matters Statistically

This study illustrates why arm-specific summaries and a treatment comparison are not interchangeable. A randomized design is intended to support a comparison between groups, but the useful inferential quantity is the contrast between them and its uncertainty. The registry record gives mean changes for each arm yet identifies the two-arm continuous comparison as missing or not estimable. That gap means readers cannot directly evaluate the central comparative question from the posted primary result.

The endpoint is measured at multiple sites per implant, and the record reports different implant counts across groups. It also reports subject counts for completion and primary analysis. This structure makes the unit of analysis and the handling of within-subject and within-implant correlation important to statistical interpretation. Such design and analysis details are often essential to understanding whether confidence intervals reflect the actual data structure; they are not reported in the registry record.

The study is described as a pilot, and the record includes a planning illustration based on an assumed fraction of the observed effect. This is a useful occasion to distinguish planning calculations from evidence collected in a trial. A planning illustration does not establish observed power or compensate for the absence of a reported contrast. Likewise, a completed status does not itself mean that all planned analyses or outcome data were posted.

For clinical researchers, the record highlights the value of registering a clear primary analysis, specifying analysis populations and missing-data procedures, and posting comparative estimates with uncertainty. Those details would make it easier to assess what the trial contributes, how precisely it answers its question, and whether its analysis aligns with its randomized design.

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 of the posted primary result is that it does not include an estimable between-group comparison. Although arm-specific mean changes and confidence intervals are listed, there is no reported contrast, p-value, or analysis entry for the continuous two-arm endpoint. The registry record therefore does not provide a formal estimate of comparative effect or its precision.

The primary analysis covered 10 of 16 subjects who completed in the inactive group and 13 of 15 who completed in the active group. The reasons for these analysis counts and the handling of excluded or missing data are not reported. The number randomized to each group is also not reported, limiting assessment of participant flow and the preservation of randomized assignment in the analysis.

The endpoint description aggregates measurements from six sites per implant and reports 26 implants in the inactive group and 38 in the active group. The statistical treatment of repeated sites and multiple implants within a subject is not reported. The registry also does not explain how measurements were weighted in the arm averages. The listed confidence intervals have no accompanying calculation method, so their assumptions and relation to the described measurement structure cannot be evaluated from the record.

The record lists several secondary outcomes but gives no multiplicity strategy or analysis details for them. It does not report the trial’s sample-size justification, a prespecified statistical plan, interim analyses, or sensitivity analyses. These absences do not show that such procedures were not conducted; they mean they are not reported in the registry record. Together, these limitations require a cautious, descriptive reading of the posted primary values.

15. Related Tutorials

16. Related Statistical Calculators

17. Sources

• ClinicalTrials.gov: Peri-implantitis Treatment: Clinical Results of Conventional Treatment vs. the Addition of Biolase — NCT03544515.
• Registry record last updated 2024-08-09; status last verified 2024-07.
• Results first posted 2024-08-09.
• 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

NCT03544515 is a completed randomized, triple-masked, parallel-group study sponsored by Columbia University. It enrolled 32 participants and compared conventional scaling and debridement with inactive laser application against the same conventional treatment with active Er,Cr:YSGG laser application. The primary outcome was change in probing depth from baseline to 9 months.

The registry reports mean changes of -0.73 mm in the inactive group and -1.36 mm in the active group, with 95% confidence intervals of -1.17 to 0.28 and -1.96 to 0.77. The primary analysis included 10 and 13 subjects, respectively. A direct two-group comparison is marked missing or not estimable. Five secondary outcomes are listed, but analysis methods, multiplicity handling, and missing-data procedures are not reported in the registry record.