This page provides an independent statistical analysis and educational interpretation of publicly reported results. ClinicalTrials.gov provides the official trial registry record. Numerical trial results on this page are restricted to the results posted in the ClinicalTrials.gov record; calculations added by Clinical Biostats are labelled as such.
1. Trial at a Glance
This page covers the registry results for Implant-fixed Restorations With ANKYLOS 6.6 mm Implants in the Edentulous Maxilla - A 5-year Follow-up Study (NCT02656823), a na na study. The primary outcome is Implant Survival Rate.
| Feature | Registry value |
|---|---|
| ClinicalTrials.gov identifier | NCT02656823 |
| Phase | NA |
| Condition | Edentulous Maxilla |
| Allocation | Not applicable (single group) |
| Design model | Single Group |
| Masking | None (open label) |
| Enrollment | 12 |
| Arms in the primary outcome | n/a |
| Lead sponsor | Dentsply Sirona Implants and Consumables |
| Results posted | Yes |
2. Clinical Question
Population
The study concerns people with an edentulous maxilla. The registry describes an intention-to-treat population for the primary outcome and records an enrollment of 12. Participant characteristics beyond the edentulous maxilla are not reported in the registry record.
Intervention
The intervention is ANKYLOS C/X Implant A 6.6, described as a 6.6 mm implant. The study summary says it assesses six short implants supporting fixed full-arch bridges. Details about how the implants were placed or how the bridges were managed are not reported in the registry record.
Comparator
There is no comparator group: the registry identifies the study as single-group, with allocation listed as NA. It therefore does not provide a concurrent control against which to estimate a comparative treatment effect.
Primary question
The primary outcome is implant survival, assessed by counting remaining implants clinically and radiographically at Visit 14, 5 years after permanent restoration. An implant removed after placement is considered a failure, whatever the reason for removal. The registry record does not report the number of implants remaining at that visit.
3. Trial Design
This is a completed, single-group clinical investigation of ANKYLOS C/X 6.6 mm implants in the edentulous maxilla. The study summary describes six short implants supporting fixed full-arch bridges, with performance assessed after 5 years in function. Enrollment was 12. The registry lists allocation as NA and masking as NONE; it does not describe a randomized allocation or a masked assessment.
The recorded study start date is 2015-11-24, and the primary completion date is 2022-12-01. The primary outcome timeframe is Visit 14, 5 years after permanent restoration. These dates describe the registry record; details of participant-level follow-up, visit timing, or the time between enrollment and restoration are not reported in the registry record.
The primary outcome is implant survival. Secondary outcomes named in the record include implant stability, marginal bone levels at subject and implant levels, probing pocket depth, plaque, bleeding on implant, oral health impact measured with OHIP-14, and prosthetic survival at subject level. The registry lists nine outcome measures and zero analysis entries. Results for these outcomes and the methods used to analyze them are not reported in the registry record.
Because this is a single-group study, its design can describe outcomes among participants receiving the intervention, but it cannot by itself separate changes associated with the intervention from other explanations. The record does not report a control condition, randomization procedure, or masking method beyond the listed values.
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
| Stage | ANKYLOS C/X Implant A 6.6 |
|---|---|
| STARTED | 12 |
| Permanent Restoration (PR), Visit 8 | 11 |
| COMPLETED | 7 |
| NOT COMPLETED | 5 |
Reasons for not completing this period:
| Reason | ANKYLOS C/X Implant A 6.6 |
|---|---|
| Adverse Event | 3 |
| Lost to Follow-up | 2 |
Analysis population for the primary outcome, as defined in the registry: Intention to treat.
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: 12 subjects received implants in the clinical investigation.
| Characteristic | Unit | ANKYLOS C/X Implant A 6.6 |
|---|---|---|
| Participants analysed | 12 | |
| Age, Continuous | Years | 60.2 (SD 12.19) |
| Sex: Female, Male: Female | Participants | 3 |
| Sex: Female, Male: Male | Participants | 9 |
| Race and Ethnicity Not Collected | Participants | — |
6. Primary Endpoint
The registry lists the primary outcome as Implant Survival Rate, measured over At Visit 14, 5 years after permanent restoration (PR)..
| Element | Registry entry |
|---|---|
| Result type | Count Of Units |
| Measure of spread | not applicable |
| Unit | Implants |
| Endpoint classification | not reduced to a single comparison |
The primary endpoint is implant survival, expressed as a count of implants. The registry defines an implant removed after placement as a failure, regardless of the reason. Survival is to be evaluated clinically and radiographically by counting the implants remaining at Visit 14, 5 years after permanent restoration. The population specified for this outcome is intention to treat.
This endpoint captures whether implants remain in place at the specified follow-up assessment. In general, a clearly defined survival endpoint can summarize device retention over a stated period. It is distinct from measures of function, tissue condition, patient-reported oral health, or prosthetic survival; the registry lists several such measures as secondary outcomes.
The record does not report the number of implants placed for the analysis, the count remaining at the visit, or an endpoint estimate. Although the outcome is titled “Implant Survival Rate,” its parameter is recorded as a count of units. A rate or proportion cannot be interpreted from the record without the relevant observed count and denominator. No confidence interval or other measure of precision for the primary outcome is reported in the registry record.
7. Why No Re-analysis Is Shown
8. Statistical Interpretation
The registry describes a study of short implants in an edentulous maxilla, with implant survival assessed at Visit 14, 5 years after permanent restoration. It defines failure as removal after placement for any reason and specifies clinical and radiographic counting of remaining implants. These definitions clarify what the primary outcome is intended to represent, but they do not establish the observed result.
The registry record does not report the primary endpoint count, an implant survival estimate, or a confidence interval. It also lists zero analysis entries. Consequently, the posted record does not support a numerical description of how many implants remained, how precisely survival was estimated, or whether the outcome varied across participants. There is no basis in the record for describing the intervention as effective or ineffective.
The enrollment of 12 gives context for the scale of the study, but it is not a substitute for the endpoint denominator. The record does not state how many implants were included in the analysis or how many participants completed the relevant visit. It is therefore not possible to infer those quantities from enrollment alone. Nor does the registry state how missing outcome observations, if any, were handled.
The study has no comparator group. Any observed result, if reported elsewhere, would describe the study group under its follow-up conditions; it would not directly estimate a difference from another treatment or from no treatment. In general, a comparison group helps distinguish an intervention-associated outcome from other influences, while a single-group result is more limited in that respect.
Several additional outcomes are named, including marginal bone level, implant stability, oral health impact, and prosthetic survival. Their inclusion indicates that the study planned to assess more than implant retention, but the registry record does not provide their results or analyses. Conclusions should therefore remain limited to the study question and the information actually recorded: the design and endpoint are described, while numerical outcome findings and their precision are not reported.
9. Statistical Methods Explained
The registry record identifies the primary outcome as a count of units: implants remaining at a follow-up visit. This is not the same as a continuous measurement such as a mean bone level. For a count endpoint, interpretation depends on both the number observed and the relevant denominator. Neither the primary count nor its denominator is reported in the registry record, so an estimate cannot be reconstructed from the information recorded.
What does implant survival mean?
The outcome definition treats any implant removed after placement as a failure, whatever the reason for removal. Remaining implants are to be counted clinically and radiographically at Visit 14, 5 years after permanent restoration. In general, a fixed follow-up assessment describes status at that assessment; it does not, by itself, provide the timing of any earlier removal or a full account of events between visits. The registry record does not report a time-to-event analysis or individual event times.
How should precision be understood?
In general, a confidence interval describes a range of values compatible with the data under the statistical method used. Its width reflects uncertainty as well as the amount and variability of information available. A point estimate without an interval can obscure how imprecisely an outcome is estimated. No primary estimate or confidence interval is reported in the registry record, and no method for calculating one is recorded. A numerical statement about precision is therefore unavailable.
What can a single-group design estimate?
In general, a single-group study can describe outcomes observed among participants receiving an intervention. Without a concurrent comparison group, it cannot directly estimate the contrast between that intervention and another treatment or control condition. Changes in outcome may also reflect factors other than the intervention. Here, the registry identifies a single group and no randomized allocation. It does not record a comparative effect estimate.
What do the analysis entries tell us?
The record lists zero analysis entries. This means no statistical analysis is described in the registry record; it does not establish that no analysis was performed outside the record. The statistical methods, any adjustment for participant or implant characteristics, and any approach to uncertainty are not reported in the registry record. The named outcomes alone do not reveal how they were analyzed.
How do planning calculations differ from trial results?
The registry’s planning description characterizes sample-size calculations as illustrations based on an observed effect, rather than as the study’s own design justification. It describes a two-sided significance level of 0.05, equal allocation between two arms, and a normal approximation, with the effect to detect set as a stated fraction of the observed effect. The description distinguishes participants per arm for non-time-to-event outcomes from total events for time-to-event outcomes. These are planning assumptions, not observed study results, and an illustrative sample-size calculation is not observed power. The record does not report the trial’s own sample-size justification. Numerical planning outputs and the observed effect used for those illustrations are not reported in the registry record.
These general principles help distinguish an endpoint definition, an analysis, and a planning calculation. For this study, the endpoint definition and some planning assumptions are recorded, but the primary result, its uncertainty, and the statistical analysis are not. No unadjusted re-calculation can be made without the posted summary statistics required for it.
10. Multiplicity, Missing Data and Analysis Populations
The registry names multiple outcomes: implant survival as the primary outcome and measures including implant stability, marginal bone level, probing pocket depth, plaque, bleeding on implant, OHIP-14, and prosthetic survival as secondary outcomes. When multiple outcomes are assessed, general statistical practice distinguishes a prespecified primary question from additional outcomes and considers how multiple inferences will be interpreted. The registry record does not report a multiplicity adjustment, a hierarchy among secondary outcomes, or a statistical analysis plan.
The record lists zero analysis entries. It therefore does not show outcome-specific estimates, tests, or uncertainty measures. This absence does not establish whether analyses were performed elsewhere; it means the registry record does not document them.
The primary population is identified as intention to treat. In general, an intention-to-treat approach aims to retain participants in the groups to which they were assigned, but the record does not describe participant allocation or how that principle was operationalized in this single-group study. It also does not report the number of participants or implants contributing to each outcome, the handling of missing observations, or any imputation or sensitivity analysis. Missing-data amounts and methods are not reported in the registry record.
Without these details, readers cannot assess whether all planned outcomes were analyzed, how incomplete follow-up affected estimates, or how strongly conclusions depend on specific analysis choices. The record’s outcome definitions are useful, but they do not fill those reporting gaps.
11. Safety Results
The registry reports serious adverse events as affected participants divided by participants at risk.
| Arm | Participants with serious adverse events | Participants at risk | Percentage |
|---|---|---|---|
| ANKYLOS C/X Implant A 6.6 | 0 | 12 | 0.0% |
Deaths
| Arm | Deaths (participants affected of at risk) |
|---|---|
| ANKYLOS C/X Implant A 6.6 | 0 of 12 |
Other (non-serious) adverse events
Participants with at least one non-serious event at or above the registry's 5% reporting threshold.
| Arm | Participants affected of at risk |
|---|---|
| ANKYLOS C/X Implant A 6.6 | 11 of 12 |
Most frequent non-serious adverse event terms
| Event term | Organ system | ANKYLOS C/X Implant A 6.6 |
|---|---|---|
| Dental implant related event | Product Issues | 8 of 12 |
| Porcelain chipping | Product Issues | 5 of 12 |
| Peri-implant tissue related event | Investigations | 4 of 12 |
| Dental abutment related event | Product Issues | 2 of 12 |
| Dental prosthesis related event | Product Issues | 2 of 12 |
| Hypertension | Cardiac disorders | 1 of 12 |
| Hand infection | Infections and infestations | 1 of 12 |
| Back injury and spinal fusion surgery | Musculoskeletal and connective tissue disorders | 1 of 12 |
| Nickel allergy | Skin and subcutaneous tissue disorders | 1 of 12 |
| Muscle spasm neck region | Musculoskeletal and connective tissue disorders | 1 of 12 |
The registry adverse-event summary lists 12 participants at risk for serious adverse events, with 0 affected, and 12 at risk for other adverse events, with 11 affected. It records 0 deaths. These are counts in the registry summary, not a comparative estimate, and no control group is listed.
The record does not provide serious adverse-event terms; the list of top serious terms is empty. It also does not specify in this summary the event descriptions, timing, duration, severity grades, or attribution to the implant. The meaning and classification of “other” adverse events should not be expanded beyond the registry’s category. In particular, the count of participants affected does not give the number of individual events.
These figures describe what is recorded in the adverse-event summary. They do not establish that no unrecorded events occurred, and they do not by themselves quantify comparative safety. The registry record does not report a safety analysis or additional context for interpreting these counts.
12. What the Result Does, and Does Not, Mean
The registry record documents a completed, single-group study enrolling 12 participants and assessing ANKYLOS C/X 6.6 mm implants in the edentulous maxilla. Its primary question concerns the number of implants remaining at Visit 14, 5 years after permanent restoration. It also identifies several secondary measures spanning implant stability, tissue findings, oral health impact, and prosthetic survival.
What the record does not establish is the primary outcome result. It does not report the number of implants remaining, an estimated survival rate, or a confidence interval. The record also contains zero analysis entries. Without those results, it is not possible to characterize the observed outcome or its precision. No conclusion that the intervention does or does not work follows from the endpoint definition alone.
The single-group design also limits interpretation of any outcome that might be reported elsewhere. A description of outcomes in this group would not be a direct comparison with an alternative intervention or control. The registry does not report a randomized comparison, and the listed allocation is NA.
The secondary outcome names indicate the range of measurements of interest, but the record does not report their results. Likewise, the adverse-event summary provides counts but not event descriptions or a comparative safety analysis. These data should be read as registry-reported observations, not as proof of a causal effect.
Overall, the record defines a clinical question and describes its follow-up target, but it does not report the numerical findings needed to answer that question. The distinction matters: a study’s completion and a clearly stated endpoint are not themselves evidence of a particular outcome.
13. Why This Trial Matters Statistically
Statistically, this study is notable for the gap between a clearly specified clinical endpoint and the absence of a reported result in the registry record. The endpoint has a stated failure definition and a follow-up time: an implant removed after placement is a failure, and remaining implants are counted at Visit 14, 5 years after permanent restoration. These details make the intended measurement understandable, but they do not provide the observed count or its precision.
The single-group design is also important. It can describe outcomes in the study group, but it does not supply a direct comparison with another treatment. A comparative question generally requires a comparator and an analysis of the contrast; neither is recorded. That distinction should guide how any later outcome information is interpreted.
The record also names multiple secondary outcomes, while documenting zero analysis entries and no results for those measures. This illustrates why endpoint definitions, analysis methods, and numerical results are separate parts of a statistical report. Knowing what was measured does not show what was observed or how uncertainty was assessed.
Finally, the stated planning calculations are illustrations, not evidence that the study was designed around those assumptions or that it had a particular level of power. Sample-size planning and observed results answer different questions. The registry record does not report the study’s own sample-size justification. For readers, the central statistical lesson is to distinguish study description from evidence about an outcome and to note when estimates and their uncertainty are absent.
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 most consequential limitation for interpreting the registry record is that it does not report the primary outcome result. Although implant survival is defined and its follow-up visit is specified, the remaining-implant count, denominator, estimate, and uncertainty are absent. The record also lists zero analysis entries, leaving the statistical approach undocumented.
The study is single-group, with allocation listed as NA and masking as NONE. Without a comparator, it cannot directly quantify a difference between this intervention and another condition. The enrollment was 12, which describes the study’s scale but does not reveal how many implants or participants contributed to the primary endpoint. The registry does not report the analyzed sample at follow-up.
Other study details relevant to interpretation are not reported in the registry record, including participant characteristics beyond the edentulous maxilla, the handling of missing data, and a statistical analysis plan. The record names secondary outcomes but does not report their results or methods of analysis. It does not state whether or how multiplicity was addressed.
The primary timeframe is described as Visit 14, 5 years after permanent restoration, while the summary describes assessment after 5 years in function. The record does not provide participant-level visit dates or further detail about follow-up duration. These limitations do not negate the stated study question, but they restrict what can be concluded from the registry information.
15. Related Tutorials
16. Related Statistical Calculators
17. Sources
- ClinicalTrials.gov: Implant-fixed Restorations With ANKYLOS 6.6 mm Implants in the Edentulous Maxilla - A 5-year Follow-up Study — NCT02656823.
- Registry record last updated 2024-02-28; status last verified 2024-02.
- Results first posted 2024-02-28.
- 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.
Continue through the Clinical Biostats statistical pathway
Use this trial's endpoint as a starting point for deeper study of effect measures, confidence intervals, and sample-size planning.
18. Record Summary
This completed, single-group study assessed ANKYLOS C/X 6.6 mm implants in the edentulous maxilla. Enrollment was 12; allocation is listed as NA and masking as NONE. The primary outcome is implant survival, defined by counting remaining implants clinically and radiographically at Visit 14, 5 years after permanent restoration. Removal after placement is considered failure, whatever the reason.
The registry record does not report the primary outcome result, its precision, or a statistical analysis. It names secondary outcomes covering implant and tissue measures, oral health impact, and prosthetic survival. The adverse-event summary records 0 participants affected by serious adverse events, 11 affected by other adverse events, and 0 deaths, with 12 at risk in each adverse-event category. These registry entries describe the study and its recorded safety counts, but do not provide a comparative estimate of outcomes.