Efficacy of Er:YAG Laser in Decontamination of Dental Implants: An In-Vitro Study: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for Efficacy of Er:YAG Laser in Decontamination of Dental Implants: An In-Vitro Study (NCT03100435), a randomized na study. The primary outcome is Percent Bacteria Biofilm.

2. Clinical Question

3. Trial Design

The registry describes NCT03100435, an in-vitro study of Er:YAG laser decontamination of dental implants. It is marked as completed. The recorded start date is 2017-04-20, and the primary completion date is 2018-10-18. The study is classified as randomized, with no masking and a parallel model. Its phase is listed as not applicable.

The outcome listing has four arms: Laser, Curette, Brush, and Control. The corresponding posted descriptions identify Er:YAG laser alone, carbon fiber curette alone, a combination of Er:YAG laser and carbon fiber curette, and no treatment. There is a naming mismatch in the record: the combination description does not use the same label as the posted outcome arm, which is called Brush. The registry does not explain this difference, so the labels should not be assumed to be interchangeable without clarification.

The record reports enrollment of 8 participants. Separately, it describes 64 collected titanium disks and says that 5 disks were removed from analysis. The posted primary outcome lists 8 observations in each arm. Because the measurements concern discs, the number of outcome observations is not itself a count of participants. The registry says that four disks were dislodged from 2 enrolled participants and one disk was excluded because of improper magnification of the SYTO 9 imaging.

The primary outcome was assessed at 3 days. The registry does not report a detailed allocation procedure, the method used to generate the random sequence, or whether allocation was concealed. Further protocol details, including the experimental procedures used to apply each approach, 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: Each subject participates in each arm, as 2 titanium discs from each subject are distributed among all 4 arms.

Overall Study

Analysis population for the primary outcome, as defined in the registry: From 64 collected titanium disks, 5 were removed from analysis. 4 disks were dislodged from 2 enrolled participants and 1 disk was excluded due to improper magnification of the SYTO 9 imaging.

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: Each participant contributes 2 titanium discs to each arm therefore creating 64 discs to analyze across 4 arms.

6. Primary Endpoint

The registry lists the primary outcome as Percent Bacteria Biofilm, measured over 3 days.

The primary endpoint is Percent Bacteria Biofilm, defined as the percent area of a titanium disc covered by bacterial biofilm. It is recorded at 3 days and summarized as a mean with a standard deviation. The measurement describes surface coverage rather than a clinical outcome in a person.

In general, a percentage of surface covered can provide a direct quantitative description of the extent of visible or measured biofilm on the experimental surface. A lower observed percentage represents less measured coverage in that particular set of discs; by itself, it does not establish why the values differ or whether the difference is reproducible. Interpretation depends on the measurement process, the experimental allocation, and the analysis used to compare groups.

The registry reports that SYTO 9 imaging was used and notes that one disk was excluded because of improper magnification. It does not describe the imaging protocol in detail, how the covered area was quantified, whether image assessment was blinded, or how measurement reliability was evaluated. Those details matter because variation in acquisition or classification could contribute to observed differences among discs.

The endpoint is a laboratory measure connected to the study's stated interest in implant-surface decontamination. It is not a direct measure of peri-implantitis, bone loss, symptoms, implant survival, or another clinical outcome. The registry does not report any secondary posted outcome measures.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

What does the mean describe?

The primary outcome is continuous: it is a percentage measurement of disc area covered by biofilm. The registry summarizes each arm using a mean and standard deviation. In general, a mean is the arithmetic average of the observations included in a group summary. It gives a central description, but it can be affected by unusually high or low values. The registry does not provide the individual disc measurements, so readers cannot check the distribution or see how much each observation contributes to the arm mean.

In general, the standard deviation describes the spread of observations around the mean. A larger standard deviation indicates more dispersion among observed values on the measurement scale. It does not quantify the precision of a treatment comparison, and it should not be read as a range containing all observations or as a confidence interval. The posted standard deviations are 24.0 for Laser, 19.15 for Curette, 10.29 for Brush, and 21.61 for Control.

What would a comparison estimate add?

A comparative analysis would quantify how the outcome differs between specified arms and describe uncertainty in that estimate. For a continuous endpoint, an analysis might report a difference in means with a confidence interval, together with a test result if one was planned and appropriate. In general, a confidence interval gives a range of values compatible with the data and the assumptions of the method. Its width conveys precision: a wider interval indicates less precise estimation. No such comparison estimate or confidence interval is posted for this endpoint.

The registry record reports no posted analyses and notes that values are missing or not estimable for a two-arm comparison of the continuous endpoint. This means the descriptive outcome summaries are available, but the inferential result needed to assess a particular pairwise contrast is not. Without that result, readers should not infer statistical significance from the ordering or separation of the arm means.

Why can multiple discs require special treatment?

In general, observations from the same participant may be more alike than observations from different participants. When several experimental units come from one participant, statistical methods may need to account for that clustering rather than treating all measurements as independent. The registry reports that four disks were dislodged from 2 enrolled participants and gives 8 outcome observations in each arm, but it does not report how disks were allocated across participants or whether a clustered analysis was used. The impact of any within-participant dependence cannot be determined from the posted summaries.

Randomized allocation can help limit systematic differences between groups when it is implemented and analyzed appropriately. The registry identifies the study as randomized, but the sequence-generation and allocation procedures are not reported in the registry record. Masking is listed as none. The record does not explain whether outcome-image assessors knew the arm assignments. In general, knowledge of assignment can matter when an outcome involves image acquisition or interpretation, although the registry does not provide enough detail to assess whether that issue affected these measurements.

What do the planning assumptions mean?

The registry describes a planning illustration based on the observed effect, using a two-sided significance level of 0.05, equal allocation between two arms, and a normal approximation. It says that the effect to detect is a stated fraction of the observed effect. In general, a sample-size calculation estimates the number of observations needed under specified assumptions to target a chosen power for detecting an effect. Such a calculation is a planning exercise, not a description of how much power the completed study achieved.

The planning assumptions do not establish the study's original design rationale. A sample-size justification for the trial is not reported in the registry record. The registry also does not report the numerical planning outputs in the registry record for this analysis, and the outcome comparison is not estimable as a posted two-arm result. Any planning illustration should therefore be understood as conditional on its stated assumptions, not as evidence about the precision or success of the completed experiment.

What can be said about multiplicity and analysis choices?

Only one primary outcome measure is listed, and no secondary outcome measures are posted. The registry does not report a multiplicity adjustment or a full statistical analysis plan. In general, when many outcomes or comparisons are tested, the chance of false-positive findings can increase; a prespecified plan can clarify which tests are primary and how multiple testing is handled. Since no inferential comparisons are posted, there is no reported set of p-values from which to evaluate such adjustments.

The record does not report an interim analysis, a model specification, or a method for handling missing observations beyond the stated disk exclusions. These omissions limit assessment of the analysis process. They do not change the descriptive meaning of the posted means and standard deviations, but they prevent a fuller evaluation of how those summaries relate to the randomized design.

10. Confidence Intervals for Each Arm

No two-arm comparison is shown for this trial, but each arm's mean can be given with a t-based 95% confidence interval computed from the posted mean, spread and number of participants.

R code and output

arm <- c("Laser", "Curette", "Brush", "Control")
n   <- c(8, 8, 8, 8)
m   <- c(32.78, 20.14, 11.8, 74.03)
sp  <- c(24, 19.15, 10.29, 21.61)
sd  <- sp      # posted standard deviations
for (i in seq_along(n)) {
  se <- sd[i] / sqrt(n[i]); h <- qt(0.975, n[i] - 1) * se
  cat(sprintf("CARM|%s|%d|%.3f|%.3f|%.3f|%.3f\n", arm[i], n[i], m[i], sd[i], m[i] - h, m[i] + h))
}

CARM  Laser  8  32.780  24.000  12.715  52.845
CARM  Curette  8  20.140  19.150  4.130  36.150
CARM  Brush  8  11.800  10.290  3.197  20.403
CARM  Control  8  74.030  21.610  55.964  92.096

11. Multiplicity, Missing Data and Analysis Populations

The registry lists one primary outcome measure: percent of the titanium disc area covered by bacterial biofilm at 3 days. It reports no secondary outcome measures. No multiplicity adjustment or prespecified hierarchy of statistical tests is reported in the registry record. In general, multiplicity becomes relevant when investigators make several statistical comparisons, because repeated testing can increase the chance of at least one apparently notable result arising by chance. The registry does not post inferential comparisons for the primary outcome, so the implications of any multiplicity procedure cannot be assessed from the reported results.

The record describes 64 collected titanium disks and says that 5 were removed from analysis. Four disks were dislodged from 2 enrolled participants, and one was excluded because of improper magnification of the SYTO 9 imaging. The registry does not report whether these exclusions were specified before analysis, whether any other observations were missing, or how missing measurements were handled beyond these descriptions.

The record reports 8 enrolled participants and 8 outcome observations in each arm. It does not explain the relationship between participants and all analyzed disks or state whether the analysis accounted for potential clustering of disks within participants. An analysis population definition, such as an intention-to-treat population, is not reported in the registry record. Nor is a detailed statistical analysis plan reported. These gaps make it difficult to determine exactly which experimental units contributed to each summary and how missing or dependent observations were handled.

12. 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.

Most frequent non-serious adverse event terms

The registry lists serious adverse events affecting 0 of 8 at risk in each of the four safety groups. Deaths are reported as 0 in each group. No serious adverse event terms are listed. For other adverse events, the record reports 2 affected among 8 at risk in each group: Er:YAG Laser, Carbon Fiber Curette, Er:YAG Laser plus Carbon Fiber Curette, and No Treatment.

These are the recorded safety counts, not comparative estimates. The registry does not provide event descriptions for the other adverse events, timing, severity, or an analysis comparing groups. In general, absence of a reported serious event in a small study does not establish that an intervention has no risk; it describes only what was recorded in this study's safety data. The in-vitro context also means these counts should not be treated as a comprehensive assessment of clinical safety.

The safety group labels include a combination arm, while the primary outcome listing uses the label Brush for one arm. The relationship between these labels is not clarified in the registry record. The adverse-event figures should therefore be read under the safety labels as recorded, without assuming that the Brush outcome label refers to the combination group.

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

The posted results describe a laboratory endpoint: the mean percentage of titanium disc surface covered by bacterial biofilm after 3 days. The reported means are 32.78 for Laser, 20.14 for Curette, 11.8 for Brush, and 74.03 for Control. The reported standard deviations show the spread of the measurements within each arm. Those descriptive summaries indicate the observed pattern in the analyzed discs, but they do not provide an inferential comparison or quantify uncertainty in differences between arms.

The registry does not report a two-arm estimate, confidence interval, or p-value for the primary outcome. It also reports no posted analyses. Therefore, the available summaries cannot establish whether observed between-arm differences are compatible with random variation, how precisely a comparative effect is estimated, or whether one approach differs from another under a specified statistical model. The study's planning assumptions do not replace a completed analysis.

The endpoint is not a clinical outcome. It does not directly measure peri-implantitis, inflammation, bone loss, implant retention, symptoms, or quality of life. The record describes an in-vitro study of titanium discs, so the observed measurements cannot by themselves establish what would occur in a clinical setting. No advice about treatment or clinical use follows from these descriptive data.

Interpretation is further limited by the distinction between participant and disc counts. The registry reports 8 enrolled participants, 64 collected disks, 5 disks removed from analysis, and 8 outcome observations in each arm. The details needed to understand the assignment and analysis of multiple disks are not reported. In addition, the outcome arm called Brush does not align clearly with the arm description of a laser-and-curette combination. Clarification would be needed to interpret that label fully.

In short, the registry reports group-level measurements and safety counts, but not the inferential analysis needed to assess comparative precision. The findings are descriptive of the recorded in-vitro measurements and should not be extended beyond that scope.

14. Why This Trial Matters Statistically

This study illustrates why an outcome summary and a treatment comparison are not the same thing. A mean describes the center of observed measurements, while a standard deviation describes their spread. Neither one alone answers how precisely two groups differ. For that, readers generally need a comparison estimate and an uncertainty measure, such as a confidence interval. The registry reports descriptive summaries but does not post those inferential results for the primary outcome.

The study also makes the unit of analysis important. Participants, titanium disks, and outcome observations are not interchangeable units. The record reports 8 enrolled participants and describes disk collection and exclusions, while each arm has 8 posted outcome observations. Understanding which units were randomized and how multiple disks relate to participants is essential for judging whether the analysis reflects the design. The registry does not provide enough detail to resolve this.

Another statistical lesson is that labels and methods need to be clear. The outcome arm called Brush and the arm description for the laser-and-curette combination are not aligned in wording. A reader cannot confidently infer that they denote the same approach from the record alone. Clear mapping between randomized groups, interventions, and analyzed outcomes is part of transparent reporting.

Finally, this record distinguishes a laboratory measurement from a clinical endpoint. Biofilm coverage on a titanium disc can characterize an experimental surface, but it is not itself a measure of clinical disease or patient outcome. Statistical interpretation must remain matched to the endpoint and study setting. The posted data are informative as descriptive measurements, while the absence of comparative analyses limits conclusions about the relative performance or precision of the study arms.

15. 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 primary limitation is the absence of a posted inferential comparison for the continuous outcome. The registry reports means and standard deviations but no test result, confidence interval, or estimated difference between arms. It also indicates that a two-arm comparison is not estimable. The descriptive pattern therefore cannot be interpreted as a statistically established difference.

The record gives 8 enrolled participants, while the outcome summaries report 8 observations per arm and the population description refers to collected titanium disks. It states that four disks were dislodged from 2 participants and one disk was excluded for improper imaging magnification. How disks were assigned across participants, whether multiple disks came from the same participant, and how dependence was handled are not reported in the registry record. These details matter for understanding the effective information in the outcome summaries and the validity of any uncertainty estimates.

The record is also limited by incomplete methodological detail. The randomization sequence and allocation procedures, image assessment methods, masking of outcome assessors, handling of missing data beyond the listed exclusions, and full statistical analysis plan are not reported. The registry marks masking as none, but does not clarify whether image assessors were aware of assignment.

There is an arm-label ambiguity: the posted outcome calls one arm Brush, whereas the arm description includes a laser-and-curette combination. The registry does not explain the naming difference. The study is in vitro and measures disc biofilm coverage, not a clinical outcome. Its descriptive findings therefore have limited scope for conclusions about peri-implantitis or patient outcomes.

16. Related Tutorials

17. Related Statistical Calculators

18. Sources

• ClinicalTrials.gov: Efficacy of Er:YAG Laser in Decontamination of Dental Implants: An In-Vitro Study — NCT03100435.
• Registry record last updated 2023-03-31; status last verified 2023-03.
• Results first posted 2023-03-31.
• 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.

19. Record Summary

NCT03100435 is a completed, randomized, non-masked, parallel in-vitro study concerning Er:YAG laser decontamination of dental implants. The record lists 8 enrolled participants and describes an outcome measured on titanium discs. The primary endpoint is the mean percentage of disc area covered by bacterial biofilm at 3 days.

The posted arm means are 32.78 for Laser, 20.14 for Curette, 11.8 for Brush, and 74.03 for Control, with a standard deviation reported for each arm. The registry does not post inferential comparisons for the primary outcome and notes that a two-arm comparison is not estimable. It reports no secondary outcome measures. Safety listings report no serious adverse events or deaths, and 2 other adverse events affected participants in each safety group. The outcome arm label Brush is not clearly reconciled with the described laser-and-curette combination.