Study to Compare Laser Assisted New Attachment Procedure (LANAP) to Traditional Treatments of Chronic Periodontitis: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for Study to Compare Laser Assisted New Attachment Procedure (LANAP) to Traditional Treatments of Chronic Periodontitis (NCT01282229), a randomized na study. The primary outcome is Gain in Clinical Attachment Level of Periodontal Tissues.

2. Clinical Question

3. Trial Design

The registry describes a randomized, double-masked, parallel study with an enrollment of 59. The condition was chronic periodontitis, and the sponsor was the Institute for Advanced Laser Dentistry. The study status is completed; the recorded start was 2010-10 and primary completion was 2014-03.

The official title describes a multi-center, single-blind study, whereas the registry masking field says double. These descriptions do not agree, and the registry record does not clarify the difference. Randomization and masking are design features, but their labels alone do not reveal how allocation was generated, who was masked, or whether masking was maintained.

The treatments were LANAP, Modified Widman Flap surgery, scaling and root planing alone, and coronal debridement alone. Arm descriptions refer to treatment of a quadrant. The record identifies the overall model as parallel, but does not describe how quadrants or participants were assigned, or how observations within a participant were handled in the analysis.

The primary outcome was gain in clinical attachment level, with measurements described at baseline, 6 months, and 12 months. Secondary outcomes listed are change in probing depth, bleeding on probing, gingival index, and discomfort. The registry records five outcome measures but no analyses. A detailed statistical plan, including the primary comparison and analytic model, is 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

Reasons for not completing this period:

Analysis population for the primary outcome, as defined in the registry: 5-6 mm baseline PD partition had a different sample size than the 7+mm partition.

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: Data are for number of quadrants

6. Primary Endpoint

The registry lists the primary outcome as Gain in Clinical Attachment Level of Periodontal Tissues, measured over Baseline, 6, 12 months.

Clinical attachment level (CAL) describes the attachment of the tooth root to the surrounding bone. The primary outcome is change in CAL, expressed in millimeters; the registry describes this change as an estimate of attachment gained following treatment. It is a continuous measure, and the specified summary is the mean with standard deviation.

As a general statistical explanation, a continuous outcome can retain more information about variation in measurements than a simple category such as improved or not improved. A mean describes the average measurement in a group, while a standard deviation describes how dispersed individual measurements are around that average. Neither quantity alone describes the precision of a treatment comparison; that requires an estimated contrast and uncertainty interval.

The registry lists baseline, 6-month, and 12-month time points. It also states that the baseline probing-depth partitions of 5-6 mm and 7+mm had different sample sizes. The record does not report a single summarized primary comparison across those partitions or time points, nor does it specify which time point or partition was designated for a primary treatment-effect estimate.

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. These are design labels rather than a complete account of the statistical methods. The official title says single blind, in contrast with the double-masking field. The record does not clarify that difference, describe the randomization procedure, or identify which study personnel or participants were masked.

What does a mean and standard deviation describe?

The primary outcome is continuous: change in clinical attachment level measured in millimeters. The registry specifies a mean and standard deviation. In general, the mean is a measure of the center of observed values, and the standard deviation describes their spread. These summaries are useful for describing outcome distributions, but do not alone establish a comparison between treatment groups. A treatment comparison would ordinarily require a defined contrast between groups, along with an estimate of its uncertainty. Such a primary analysis is not reported in the registry record.

Why does the time point matter?

The record lists baseline, 6-month, and 12-month measurements. In general, repeated measurements on the same participant are related rather than independent. Analyses of repeated observations need to account for that relationship if they use multiple time points together. Alternatively, an analysis may focus on a specified follow-up time or change from baseline. The registry record does not report which approach was used, nor does it identify a single primary time point for a treatment contrast.

Why do the baseline probing-depth partitions matter?

The primary outcome description says the 5-6 mm and 7+mm baseline probing-depth partitions had different sample sizes. Different group sizes can affect the precision of estimates, and the way results are combined across partitions can affect the overall interpretation. As a general point, stratification or subgroup analysis should be interpreted in light of how it was planned and whether it was part of the primary analysis. The registry record does not explain how these partitions were defined for analysis, how their results were combined, or whether treatment effects were assessed separately within them.

What can randomization and masking tell readers?

Random assignment is generally intended to reduce systematic differences between treatment groups at the time of assignment. Masking is generally intended to limit the influence of knowledge about treatment on care, measurement, or reporting. These safeguards do not eliminate all possible bias, and their usefulness depends on the procedures used. The registry provides the labels randomized and double masked, but does not report procedural details. The official title’s single-blind wording adds an unresolved inconsistency.

How should a planning calculation be understood?

General sample-size calculations estimate the amount of information needed for a future study under chosen assumptions. The registry’s stated planning assumptions describe a two-sided significance level of 0.05, equal allocation between two arms, and a normal approximation, with the effect to detect expressed as a fraction of an observed effect. Such an illustration is for planning; it is not observed power and does not measure the probability that the completed study detected a real effect. The record does not report the study’s own sample-size justification or a statistical analysis plan.

The registry record does not report a primary estimate, confidence interval, or p-value. Without a reported analysis, the design labels and outcome definitions cannot be used to reconstruct the treatment comparison. Any statistical description should distinguish the recorded design and measurement plan from results that are not reported.

10. Multiplicity, Missing Data and Analysis Populations

The primary outcome has multiple time points and baseline probing-depth partitions with different sample sizes. There are also three named alternatives to LANAP, and the record lists secondary outcomes for probing depth, bleeding on probing, gingival index, and discomfort. This creates several possible comparisons and outcome summaries. In general, when many hypotheses are tested, the chance of at least one apparently unusual result can increase unless the analysis plan addresses multiplicity. The registry record does not report a multiplicity strategy or identify a single primary contrast and time point.

Missing-data handling is not reported in the registry record. There is no description of how absent follow-up measurements were addressed, whether reasons for missingness were recorded, or whether sensitivity analyses were conducted. As a general matter, missing outcomes can affect both the size and precision of an estimate, particularly when the likelihood of missingness is related to participants’ outcomes or treatment experience.

The registry record also does not identify the analysis population, such as whether the primary analysis followed randomized assignment or included only participants with observed measurements. It does not describe exclusions, adherence criteria, or the handling of participants who contributed measurements to more than one treatment quadrant. These are not details that can be inferred from the enrollment figure, arm descriptions, or adverse-event denominators. The absence of this information limits assessment of how the study’s design translated into the reported analysis; no analysis is reported in the registry record.

11. Safety Results

The registry reports serious adverse events as affected participants divided by participants at risk.

Other (non-serious) adverse events

Participants with at least one non-serious event at or above the registry's 5% reporting threshold.

The registry lists 59 at risk in each of the four treatment groups. For each group, it records 0 serious adverse events and 0 other adverse events. Death counts are recorded as null, which is not the same as a reported count of zero. These entries describe what the registry reports for the listed categories.

As a general statistical point, a zero count does not establish that the underlying risk is zero. The interpretation of an adverse-event count depends on how events were defined and collected, how long participants were followed, and whether the record is complete. Those details are not reported in the registry record. The repeated at-risk counts should be read as group-specific entries, not added together.

The record does not provide event descriptions or explain the distinction between serious and other events. It also does not report a safety comparison or uncertainty estimate. Therefore, the entries alone do not establish that the treatments have equivalent safety profiles or that events were absent beyond the registry’s recorded categories and follow-up.

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

The record establishes that a randomized study compared LANAP with Modified Widman Flap surgery, scaling and root planing alone, and coronal debridement alone for chronic periodontitis. Its primary outcome was mean change in clinical attachment level, measured in millimeters at baseline, 6 months, and 12 months. The study is marked completed, and the record lists an enrollment of 59.

Those details describe the intended question and study structure, not the observed comparative result. The registry record reports no analyses and does not provide group-level primary outcome results, a treatment-effect estimate, a confidence interval, or a p-value. It therefore does not show the direction or magnitude of differences in attachment-level change, or the precision of any such difference. No claim that one treatment is better, worse, or equivalent to another can be supported by the primary results in this record.

In general, a nonsignificant finding, if one were reported, would not by itself demonstrate equivalence; equivalence requires a defined margin and an analysis designed to assess it. Similarly, a difference in group means would need to be interpreted in relation to uncertainty and clinical context. Neither type of conclusion is possible without the relevant outcome estimates and analysis details.

The listed adverse-event counts provide a separate descriptive record of serious and other events. They do not fill the gap in the efficacy results, and they do not establish equivalence in safety. The registry’s null death entries should not be converted into zero counts.

The appropriate reading is limited: the registry record documents the trial’s stated design, endpoint, outcome schedule, and recorded event counts, but does not report the comparative outcome analysis needed to answer its primary question.

13. Why This Trial Matters Statistically

This trial raises statistical questions that are common in studies comparing several treatments and measuring outcomes over time. It has four treatment descriptions, a continuous primary outcome, multiple follow-up times, and baseline probing-depth partitions with different sample sizes. Each of these features makes the definition of the primary comparison important for interpreting a result.

As a general principle, an estimate is meaningful only when readers can identify what is being compared, at what time point, and in which analysis population. If several comparisons are possible, prespecifying a primary contrast helps distinguish the main question from secondary or exploratory analyses. If measurements are repeated, the analysis should account for their relationship. The registry record does not report these analytic details or a primary outcome result, so it illustrates why design information and results reporting are both needed for statistical interpretation.

The record also shows that trial metadata should be read carefully: its masking field says double, while the official title describes a single-blind study. Such inconsistencies do not determine the study’s results, but they leave readers without a clear account of the masking procedures.

Finally, a completed-study label is not a substitute for a posted analysis. A transparent report of group summaries, treatment contrasts, uncertainty, handling of repeated measures and missing outcomes, and safety follow-up would be needed to evaluate the comparative evidence. The current registry record is useful for identifying the study question and the limits of what can be concluded from its posted information.

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 central limitation of the registry record is that it reports no analyses for the primary outcome. It contains no comparative CAL estimates, uncertainty intervals, or statistical test results. As a result, readers cannot assess the magnitude, direction, or precision of the treatment comparisons from this record.

The outcome is listed at baseline, 6 months, and 12 months, but the record does not identify a single primary follow-up comparison or describe how measurements over time were analyzed. It notes different sample sizes for the 5-6 mm and 7+mm baseline probing-depth partitions without explaining how those partitions were incorporated in the analysis. The record also does not state how multiple treatment comparisons and secondary outcomes were handled.

Important analysis details are not reported in the registry record, including the statistical plan, analysis population, missing-data methods, and handling of observations associated with treatment by quadrant. The official title’s single-blind wording also differs from the double-masking field, without an explanation. These gaps prevent a detailed assessment of the intended analysis and its implementation.

The adverse-event record lists zero serious and other events for each group, but does not describe event ascertainment, definitions, follow-up completeness, or uncertainty. Death entries are null rather than numerical zeroes. These limitations are specific to interpretation of the registry record and should not be mistaken for evidence that the study itself had no additional procedures or analyses.

15. Related Tutorials

16. Related Statistical Calculators

17. Sources

• ClinicalTrials.gov: Study to Compare Laser Assisted New Attachment Procedure (LANAP) to Traditional Treatments of Chronic Periodontitis — NCT01282229.
• Registry record last updated 2015-10-14; status last verified 2015-09.
• Results first posted 2015-10-14.
• 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

NCT01282229 is a completed randomized study of LANAP compared with Modified Widman Flap surgery, scaling and root planing alone, and coronal debridement alone in chronic periodontitis. The registry lists an enrollment of 59 and identifies the sponsor as the Institute for Advanced Laser Dentistry.

The primary outcome is mean change in clinical attachment level in millimeters, with measurements at baseline, 6 months, and 12 months. The record notes different sample sizes for the 5-6 mm and 7+mm baseline probing-depth partitions. It lists secondary outcomes of probing depth, bleeding on probing, gingival index, and discomfort.

No analyses are reported in the registry record, and it does not provide a primary treatment-effect estimate. The masking field says double, while the official title says single blind. Serious and other adverse-event counts are recorded as zero in each listed group; death entries are null.