Chesterfield Micro-implant Study Involving Three Types of Anchorage Methods in Orthodontics: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for Chesterfield Micro-implant Study Involving Three Types of Anchorage Methods in Orthodontics (NCT00995436), a randomized na study. The primary outcome is Anchorage Loss Measured From 3-D Model Scanning.

2. Clinical Question

The study set out to compare three approaches to anchorage reinforcement in orthodontic treatment. Its stated hypothesis was that there would be no difference in the amount of anchorage loss among the methods. The registry describes a randomized clinical trial in which participants were assigned to headgear, miniscrews, or a Nance palatal arch.

The primary endpoint is anchorage loss measured from 3-D model scanning, expressed as a mean in millimetres with standard deviation. The registry also describes anchorage loss assessed from lateral cephalometric radiographs and patient perceptions of the treatment methods, including surgical experience. Patient perception is listed as a secondary outcome. These measures concern different aspects of treatment: the primary endpoint is a continuous measurement of anchorage change, while the perception outcome concerns participants’ experiences.

The registry record does not report group-level primary outcome values or a numerical comparison among the methods. It therefore does not establish whether the observed anchorage loss differed between groups, or how precisely any difference was estimated.

3. Trial Design

The record describes a randomized, single-masked, parallel-group clinical trial with three anchorage methods. The listed enrollment is 78, and the study status is completed. The listed condition terms are malocclusion and Class II buccal segment relationship. The setting described in the study summary is a district general hospital orthodontic department.

The intervention groups were headgear, miniscrews, and a Nance palatal arch. The descriptions of the headgear schedule are not consistent across the registry record: the study summary says participants would be asked to wear it 12-14 hours per day, while the arm description states 100 hours per week. The registry record does not clarify this difference. The miniscrew arm is described as using miniscrews to supplement anchorage. The Nance arm is described as using a palatal arch to fix molars together with an arch.

The listed study start is 2008-07, and primary completion is listed as 2013-10. The study is marked completed. The phase is listed as NA. The masking entry says single, but the identity of the masked party is not reported in the registry record. Details about the randomization sequence, allocation concealment, and how assignments were implemented are not reported in the registry record.

The primary outcome is anchorage loss measured from 3-D model scanning, with a 2 years timeframe. The registry also describes radiographic measurement and records at three points, but it does not explain the measurement schedule or how the multiple measures relate to the primary endpoint. The registry lists two outcome measures and six analyses; it does not give the numerical results or enough detail to identify the specific estimand and contrast for each analysis.

The sponsor is Chesterfield and North Derbyshire Royal Hospital. The record’s brief description says the analysis would use an intention-to-treat basis and basic descriptive statistics and univariate tests, but the description ends mid-sentence. Additional statistical-plan details 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: 90 patients assesses as eligible. 12 chose not to take part

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 Anchorage Loss Measured From 3-D Model Scanning, measured over 2 years.

The primary endpoint is anchorage loss measured from 3-D model scanning. It is specified as a continuous measure summarized by a mean and standard deviation, in millimetres, with a timeframe of 2 years. The registry’s study summary also describes measuring anchorage loss from lateral cephalometric radiographs and 3-D model scanning, with records taken at three points. It does not specify the precise landmarks, calculation of the measurement, or which records define the primary endpoint.

In general, an endpoint is a measured outcome used to assess a study question. Here, anchorage loss is relevant because the trial compares methods intended to reinforce anchorage during orthodontic treatment. A continuous measurement can retain information about the amount of change rather than reducing it to a category. A group mean describes the average measured value, while the standard deviation describes variation among measurements within a group. Neither alone shows the uncertainty around a comparison between groups.

The registry record does not report group means, standard deviations, a between-group estimate, or a confidence interval for this endpoint. It also does not report a numerical result for the radiographic measure. Consequently, the stated endpoint and measurement approach can be described, but the size and precision of the observed differences cannot be assessed from the registry record.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

What does a mean and standard deviation describe?

The primary outcome is a continuous measure of anchorage loss, summarized as a mean and standard deviation. In general, the mean describes the centre of a set of measurements. The standard deviation describes how spread out individual measurements are around that mean. These summaries answer different questions: a mean gives an average level, while a standard deviation describes variation among participants or observations.

A comparison of group means would address whether the average measured anchorage loss differs between methods. Interpreting that comparison also requires an estimate of its uncertainty. A confidence interval is a general way to show the precision of an estimated effect and the range of values compatible with the data and model assumptions. The registry record does not report the means, standard deviations, comparison estimate, or confidence interval for the primary endpoint.

Why does the measurement schedule matter?

The study summary says records would be taken at three points, while the primary outcome entry specifies a 2 years timeframe. Repeated measurements can describe change over time, but the analysis must clarify which measurement or change defines the endpoint and how observations from the same participant are handled. In general, measurements from one participant are related rather than independent. A method that treats related records appropriately can affect both the estimated comparison and its uncertainty. The registry record does not report the precise time points, the calculation of anchorage loss, or the method used to account for repeated measurements.

The record refers both to 3-D model scanning and lateral cephalometric radiographs. These are distinct measurement approaches. The primary endpoint is specifically named as 3-D model scanning, but the registry does not explain how the radiographic outcome relates to it, whether the measurements were compared for agreement, or which measurement was used in each of the six listed analyses.

What does randomization contribute?

In general, random assignment is intended to make treatment groups comparable, on average, with respect to factors present before treatment. This can support a fair comparison, but it does not guarantee that groups will be identical, and it does not prevent problems from missing outcomes, departures from assigned treatment, or measurement differences. The registry labels allocation as randomized. Details of sequence generation, concealment, and implementation are not reported in the registry record, so those aspects cannot be assessed from the registration information.

The study is described as single-masked. Masking can reduce the influence of knowledge of assignment on some parts of study conduct or outcome assessment, depending on who is masked. The registry does not say who was masked or how masking was maintained. Because the endpoint involves model scanning, information about the assessor and measurement procedures would be relevant to understanding possible measurement bias, but that information is not reported in the registry record.

What can be inferred from the analysis description?

The brief study description says analyses would follow an intention-to-treat basis. In general, intention-to-treat analysis compares participants according to their randomized group, even when treatment received differs from assignment. This approach can preserve the benefits of randomization when implemented with appropriate outcome data and clearly defined methods. The registry record does not report how the intention-to-treat population was defined, whether it was used in the final analyses, or how missing outcome measurements were addressed.

The description also mentions basic descriptive statistics and univariate tests, but ends before the methods are fully described. A univariate test generally examines an outcome in relation to a single grouping or explanatory factor. That broad label does not identify the specific test, its assumptions, the comparison being tested, or whether the analysis accounted for repeated measurements or other design features. The specific primary analysis and its assumptions are not reported in the registry record.

How should planning estimates be understood?

The record describes planning illustrations 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 the effect to detect is a stated proportion of the observed effect. These are planning assumptions, not results from the trial and not evidence about the probability that the study detected an effect. The record does not give the numerical planning estimates or the observed effect used to generate them.

In general, sample-size planning estimates depend on the target effect, variability, significance level, power target, allocation, and analysis assumptions. If the assumed effect is smaller, more participants may be needed to distinguish it from random variation, all else being equal. Such estimates are illustrations for planning, not observed outcomes and not “observed power.” The registry record does not report the trial’s own sample-size justification, so the planning illustrations should not be treated as the original design rationale.

The statistical methods information is therefore incomplete for evaluating the reported analyses. The record identifies randomization, a continuous primary endpoint, an intention-to-treat intention, and broad analysis language. It does not report the estimator, model, uncertainty measures, missing-data method, detailed comparison plan, or numerical results.

10. Multiplicity, Missing Data and Analysis Populations

The trial includes three anchorage methods, a primary endpoint, a patient-perception outcome, multiple measurement approaches, and records described at three points. This creates several possible comparisons and outcome analyses. In general, when many statistical questions are examined, the chance of at least one apparently notable result can increase unless the analysis plan defines the primary comparisons and addresses multiplicity where appropriate. The registry record does not report a multiplicity strategy or identify which of the six listed analyses were primary, secondary, or exploratory.

The brief description states that analyses would be conducted on an intention-to-treat basis. It does not report the final analysis population or confirm whether the posted analyses followed that intention. The registry lists enrollment of 78, but the number with available primary endpoint data in each group is not reported in the registry record.

Missing data can affect a comparison if outcome availability differs between groups or relates to the measured outcome. In general, an analysis should describe the amount and pattern of missingness and explain how it was handled. The registry record does not report missing outcome counts, reasons for missing measurements, imputation, or sensitivity analyses.

The record does not report the detailed statistical analysis plan, the protocol’s sample-size justification, or interim analyses. Those details should not be inferred from the mention of descriptive statistics and univariate tests. Without this information and the numerical results, the extent to which multiplicity, missing outcomes, and analysis populations affected the findings cannot be evaluated.

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 0% reporting threshold.

The registry’s adverse-event entries list Headgear with 23 participants at risk, Miniscrews with 22 participants at risk, and Nance Palatal Arch with 26 participants at risk. For each group, the serious adverse event count is 0 and the other adverse event count is 0. The deaths field is null for the listed groups, so a death count is not reported in the registry record.

These entries should be read as counts recorded for the listed groups, not as a complete characterization of safety. In general, observing zero events in a group does not establish that the underlying risk is zero. Interpretation depends on how events were defined, how they were collected, the observation period, and whether all relevant events were reported. The registry does not provide event definitions, follow-up details for safety, or a narrative explaining the entries.

The study also lists patient perception of treatment methods, including surgical experience, as a secondary outcome. The registry record does not report numerical results for that outcome. The adverse-event figures therefore do not describe participants’ perceptions and cannot substitute for those results.

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

The registry record identifies a completed randomized trial comparing headgear, miniscrews, and a Nance palatal arch for orthodontic anchorage reinforcement. It specifies anchorage loss measured by 3-D model scanning as the primary endpoint, with a 2 years timeframe, and describes patient perception as a secondary outcome. These details establish the subject and broad structure of the comparison.

The record does not report the numerical results for the primary endpoint. It gives no group means, standard deviations, between-group estimates, confidence intervals, or p-values. As a result, the direction and size of any observed difference, and the precision with which it was estimated, cannot be determined from the registry record. The stated hypothesis that there would be no difference is not evidence that the methods produced the same result.

Likewise, the record does not provide numerical patient-perception results or a detailed description of the analyses. The listed zero serious and other adverse events are limited to the entries and group denominators recorded; they do not establish that no safety concerns occurred in all contexts or that risks are absent.

In general, a randomized design can support comparisons between assigned groups, but conclusions depend on the quality of implementation, outcome measurement, follow-up, and analysis. The registration information does not give enough detail to assess all of these elements. It also does not report the trial’s own sample-size justification or the detailed analysis plan.

The most defensible reading is therefore narrow: the registry documents the intended comparison and some design and safety information, but does not report the outcome data required to judge the primary statistical question. No conclusion about the relative anchorage loss among the methods can be drawn from the numerical results in this record because those results are not reported.

13. Why This Trial Matters Statistically

This trial is statistically relevant because it places three distinct anchorage methods in a randomized parallel-group comparison and identifies a continuous measurement as its primary endpoint. A continuous outcome can retain information about the amount of anchorage loss, while random allocation is intended to support comparability between groups. The design raises practical analysis questions about measurement timing, repeated records, and how the groups should be compared.

The record also illustrates why a clearly stated outcome is not enough to support interpretation. The endpoint name, unit, summary measure, and timeframe are documented, but the group results and uncertainty estimates are not. Without them, readers cannot distinguish a small imprecise difference from a larger, more precisely estimated one. They also cannot judge whether the stated no-difference hypothesis is consistent with the data.

There are additional transparency issues relevant to statistical appraisal. The registry describes three measurement points, multiple measurement approaches, six analyses, and two outcome measures, but does not explain the relationship among them or report a multiplicity plan. It states an intention to analyze on an intention-to-treat basis but does not report how missing outcome data or the final analysis population were handled.

The record’s planning assumptions are also distinct from the trial’s own design justification. Planning illustrations based on an observed effect do not reveal how the trial’s enrollment was originally chosen, and they cannot replace the missing outcome results. This distinction matters because a planning calculation and an observed treatment comparison answer different questions.

Overall, the record makes the study question and broad design identifiable while leaving key elements of statistical interpretation unavailable. It is a useful example of why registry descriptions, analysis plans, and reported numerical outcomes each contribute different information to evaluation of a clinical trial.

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 for interpreting this trial from the registry record is the absence of numerical primary outcome results. Group means, standard deviations, treatment contrasts, confidence intervals, and p-values are not reported. The primary statistical question therefore cannot be answered from the posted registry information.

The measurement description is incomplete. The primary endpoint names 3-D model scanning, while the study summary also mentions lateral cephalometric radiographs and records at three points. The record does not identify the exact measurement definition, the timing of each record, or how repeated measurements were incorporated into the analyses.

The intervention descriptions are not fully consistent for headgear use: the study summary states 12-14 hours per day, whereas the arm description states 100 hours per week. The registry does not explain the difference. It also does not report adherence, crossover, or deviations from assigned treatment.

Important design and analysis details are not reported in the registry record, including who was masked, how randomization was implemented, the final analysis population, missing-data handling, and the specific tests or models used. The brief statistical description is incomplete, and the detailed analysis plan, interim analyses, and trial-specific sample-size justification are not reported.

Finally, the safety entries provide event counts and group-specific numbers at risk but do not include event definitions, follow-up detail, or death counts. These limits restrict interpretation of safety as well as efficacy-related outcomes.

15. Related Tutorials

16. Related Statistical Calculators

17. Sources

• ClinicalTrials.gov: Chesterfield Micro-implant Study Involving Three Types of Anchorage Methods in Orthodontics — NCT00995436.
• Registry record last updated 2016-08-05; status last verified 2016-08.
• Results first posted 2016-08-05.
• 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

NCT00995436 is a completed randomized, single-masked, parallel-group trial titled “Chesterfield Micro-implant Study Involving Three Types of Anchorage Methods in Orthodontics.” Its official title is “Efficiency and Effectiveness of Three Methods of Anchorage Reinforcement in Orthodontics.” The registry lists enrollment of 78 and conditions of malocclusion and Class II buccal segment relationship.

The trial compares headgear, miniscrews, and a Nance palatal arch. The primary endpoint is anchorage loss measured from 3-D model scanning, summarized as a mean and standard deviation in millimetres, with a 2 years timeframe. Patient perception, including surgical experience, is listed as a secondary outcome.

The record lists a study start of 2008-07 and primary completion of 2013-10. It states an intention to use intention-to-treat analysis, but does not report numerical primary outcome results, detailed analysis methods, or missing-data handling. The adverse-event entries list zero serious and zero other events in each group; death counts are not reported in the registry record.