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 Animal Assisted Therapy in Dentistry (NCT04708028), a non-randomized na study. The primary outcome is Mean Salivary Amylase Levels Throughout Dental Visit.
| Feature | Registry value |
|---|---|
| ClinicalTrials.gov identifier | NCT04708028 |
| Phase | NA |
| Condition | Anxiety |
| Allocation | Non-Randomized |
| Design model | Parallel |
| Masking | Single |
| Enrollment | 40 |
| Arms in the primary outcome | n/a |
| Lead sponsor | University of North Carolina, Chapel Hill |
| Results posted | Yes |
2. Clinical Question
Population
Children undergoing a dental procedure. The registry description refers to a child having a salivette swab placed in the cheek, but further eligibility criteria and participant characteristics are not reported in the registry record.
Intervention
In the Dog Therapy arm, participants were introduced to a therapy dog and allowed to pet it for up to 2 minutes before the dental procedure.
Comparator
The Control arm had no exposure to the therapy dog. The study is non-randomized, so the arms should not be treated as a like-for-like comparison.
Primary question
The primary outcome is mean salivary amylase throughout the dental visit, reported in U/mL. The study description frames this biomarker as a way to measure stress during a dental procedure. The registry record does not report the arm-specific means or a numerical comparison between arms.
3. Trial Design
The registry record describes a cross-sectional prospective study of physiologic biometrics and perceptions of stress during a dental procedure, with or without a therapy dog present. It lists a parallel model and non-randomized allocation. Participants were assigned to a Control arm, with no dog exposure, or a Dog Therapy arm, in which participants could meet and pet the dog for up to 2 minutes before the procedure. Because allocation was not randomized, differences between the arms could reflect factors other than dog exposure. The record itself cautions that the arms are not a like-for-like control comparison.
The record lists an enrollment of 40 and a status of COMPLETED. It gives the study start as 2021-07-26 and primary completion as 2023-06-22. These registration details do not establish how many participants contributed data to the primary analysis, or whether all enrolled participants completed all measurements; those details are not reported in the registry record. The listed phase is NA.
Masking is recorded as SINGLE, but the identity of the masked party and what information was masked are not reported in the registry record. The protocol details, recruitment setting, eligibility rules, assignment process, and any procedures intended to address differences between arms are also not reported in the registry record. The registry lists two outcome measures and eight analyses, but does not identify the second outcome measure or describe the analyses in enough detail to establish which methods were used for the primary comparison.
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 | Control | Dog Therapy |
|---|---|---|
| STARTED | 22 | 18 |
| COMPLETED | 21 | 18 |
| NOT COMPLETED | 1 | 0 |
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.
| Characteristic | Unit | Control | Dog Therapy | Total |
|---|---|---|---|---|
| Participants analysed | 21 | 18 | 39 | |
| Age, Categorical: <=18 years | Participants | 21 | 18 | 39 |
| Age, Categorical: Between 18 and 65 years | Participants | 0 | 0 | 0 |
| Age, Categorical: >=65 years | Participants | 0 | 0 | 0 |
| Age, Continuous | years | 9.9 (SD 2.0) | 9.2 (SD 2.1) | 9.6 (SD 2.0) |
| Sex: Female, Male: Female | Participants | 12 | 11 | 23 |
| Sex: Female, Male: Male | Participants | 9 | 7 | 16 |
| Ethnicity (NIH/OMB): Hispanic or Latino | Participants | 12 | 14 | 26 |
| Ethnicity (NIH/OMB): Not Hispanic or Latino | Participants | 9 | 4 | 13 |
| Ethnicity (NIH/OMB): Unknown or Not Reported | Participants | 0 | 0 | 0 |
| Race (NIH/OMB): American Indian or Alaska Native | Participants | 0 | 0 | 0 |
| Race (NIH/OMB): Asian | Participants | 1 | 0 | 1 |
| Race (NIH/OMB): Native Hawaiian or Other Pacific Islander | Participants | 0 | 0 | 0 |
| Race (NIH/OMB): Black or African American | Participants | 3 | 3 | 6 |
| Race (NIH/OMB): White | Participants | 4 | 2 | 6 |
| Race (NIH/OMB): More than one race | Participants | 13 | 13 | 26 |
| Race (NIH/OMB): Unknown or Not Reported | Participants | 0 | 0 | 0 |
| Region of Enrollment: United States | Participants | 21 | 18 | 39 |
6. Primary Endpoint
The registry lists the primary outcome as Mean Salivary Amylase Levels Throughout Dental Visit, measured over Up to end of dental visit; a total average between 60 to 90 minutes.
| Element | Registry entry |
|---|---|
| Result type | Mean |
| Measure of spread | Standard Deviation |
| Unit | U/mL |
| Endpoint classification | Continuous Endpoint |
The primary endpoint is titled “Mean Salivary Amylase Levels Throughout Dental Visit.” It is a continuous measure reported in U/mL, with the mean and standard deviation named as the summary measures. The specified timeframe is up to the end of the dental visit, described as a total average between 60 to 90 minutes. The measurement description says that a salivette swab is placed in the child’s cheek to absorb saliva.
Salivary amylase is used in this study as a physiologic biomarker intended to reflect stress during the dental procedure. A continuous endpoint can retain information about the range of measured values rather than reducing observations to categories. Comparing group averages can describe whether the recorded values differ between the study arms, while the standard deviation describes the spread of individual values around a group mean. Those summaries alone do not establish why any difference occurred.
The registry record does not report the numerical mean or standard deviation for either arm, the estimated difference between arms, or a confidence interval for that difference. It therefore does not allow the direction, size, or precision of the primary-endpoint comparison to be assessed. The record also does not specify the timing of individual saliva samples or how the visit-level average was constructed beyond the stated timeframe.
7. Why No Re-analysis Is Shown
8. Statistical Interpretation
The record identifies a clinically relevant measurement question: whether salivary amylase values during a dental visit differ between participants who had brief contact with a therapy dog beforehand and those who had no dog exposure. However, the details available in the registry record do not include the numerical primary-endpoint results. There are no arm-specific means or standard deviations, no numerical treatment contrast, and no reported confidence interval or p-value for that endpoint. Without those results, it is not possible to describe the observed direction or magnitude of the comparison, or how precisely it was estimated.
The study is non-randomized. Even if a numerical difference were available, it would describe an association between the study arms rather than isolate an effect of dog exposure. Participants may differ between arms in ways that are related to salivary amylase. The registry record does not report whether such differences were measured, adjusted for, or otherwise addressed. The record explicitly warns that the arms are not a like-for-like control comparison. Consequently, an unadjusted difference would require particular caution and could not by itself establish that the dog exposure caused the difference.
A mean and standard deviation serve different purposes. The mean locates the center of the observed values; the standard deviation describes their variability. Neither gives the precision of a between-arm estimate on its own. A confidence interval would convey a range of values compatible with the data under the assumptions of the analysis, but no such interval is reported in the registry entries. A p-value, if reported, would address compatibility with a specified statistical model and null hypothesis; it would not quantify the size or practical importance of a difference. No p-value is reported for the primary endpoint in these details.
The registry lists two outcome measures and eight analyses, but does not identify all outcomes or explain which analyses correspond to which questions. Thus, it is not possible to determine whether the reported analysis set was complete, whether analyses were adjusted, or how multiple comparisons were handled. The registry record also does not state the primary analysis population or how missing measurements were treated. These omissions limit interpretation even apart from the absent numerical endpoint results.
The recorded completion status and enrollment do not fill these gaps. Enrollment is listed as 40, but the record details do not establish the number contributing to each primary analysis. The serious and other adverse-event entries report zero events in the listed groups, but those entries do not provide evidence about the primary biomarker comparison. Overall, the registry entries define the study question and design, but do not support a conclusion about the observed salivary amylase contrast or its precision.
9. Statistical Methods Explained
The registry describes a continuous primary outcome summarized by a mean and standard deviation. The mean is the arithmetic center of measured values, while the standard deviation indicates how dispersed those values are around the mean. A larger standard deviation means observations are more spread out; it is not the same as uncertainty in the estimated mean or uncertainty in a difference between group means. Estimating the latter requires information about the data and the analysis model.
What would a confidence interval convey?
As a general statistical concept, a confidence interval describes uncertainty around an estimate under a specified model and its assumptions. For a comparison of means, an interval around the between-arm estimate helps readers assess which values are compatible with the data and how narrowly the estimate is determined. An interval that is wide indicates less precision than a narrow interval. It does not correct bias from non-randomized allocation, unmeasured differences between groups, or inappropriate analysis choices. No confidence interval for the primary comparison is reported in the registry record.
What does a p-value answer?
As a general explanation, a p-value measures how unusual the observed data, or data more extreme, would be under a specified null hypothesis and statistical model. It is not the probability that the null hypothesis is true, and it does not state the size or importance of a difference. Interpretation depends on the analysis plan, data quality, and assumptions. The primary-endpoint p-value and the exact inferential procedure are not reported in the registry record.
Why does non-randomized allocation matter?
In a randomized comparison, assignment by chance is intended to make baseline characteristics comparable on average. This study is recorded as non-randomized, so that protection is not available by design. Differences in measured or unmeasured characteristics could be associated with both arm membership and the outcome. Statistical adjustment can address some measured differences when the relevant variables and methods are specified, but it cannot guarantee removal of confounding. The registry record does not report an adjustment strategy or the information needed to assess one. It also states that the arms are not a like-for-like control comparison.
How should planning calculations be read?
The record describes planning illustrations based on the observed effect, using a two-sided significance level of 0.05, equal allocation between arms, and a normal approximation. The effect to detect is described as a stated fraction of the observed effect. Such calculations are planning exercises, not evidence that the study had a particular probability of detecting an effect after it was run. They are not observed power. Their interpretation depends on the effect estimate used and the assumptions of the calculation. The registry entries do not give the numerical planning outputs or identify a sample-size justification used in the trial’s own design. The planning illustrations should therefore not be mistaken for a prospectively specified design calculation or a result of the trial.
What does the continuous-outcome model need to account for?
As a general concept, an analysis of a continuous outcome should reflect how observations were collected and whether the model assumptions are reasonable. If measurements are strongly skewed, contain influential values, or have unequal variability between groups, a simple comparison of means may not describe uncertainty well unless the method accommodates those features. Repeated measurements within a visit may also be related rather than independent; how to handle that depends on the sampling schedule and the endpoint construction. The registry record does not report the individual sampling schedule, distributional checks, treatment of repeated measurements, or the model used.
Over-dispersion is most often discussed for count outcomes, where observed variability exceeds what a chosen count model expects. It is not automatically a concern for every continuous measure, and it should not be assumed for this endpoint. More generally, outcome variability and dependence should be assessed using the data and an appropriate model. The registry description gives a visit-level average but does not provide enough detail to evaluate the underlying observations or model assumptions.
What can recalculation establish?
As a general matter, a simple recalculation from posted summary statistics can check an unadjusted comparison under its own assumptions. It cannot reproduce a sponsor’s adjusted analysis without the relevant model and data, and it does not resolve confounding inherent in non-randomized allocation. The registry entries do not include the primary summary statistics or a sponsor analysis for comparison, so no recalculated primary estimate can be interpreted from them. Any planning illustration based on an observed effect remains distinct from an estimate of observed power.
10. Multiplicity, Missing Data and Analysis Populations
The registry record lists two outcome measures and eight analyses, but it does not describe the full set of outcomes, identify all analysis questions, or explain how the analyses relate to one another. It does not report a multiplicity strategy, such as a method for controlling the chance of false-positive findings across several statistical tests. Without that information, the risk of selective emphasis among multiple results cannot be assessed. This does not establish that a particular adjustment was or was not performed; the method is not reported in the registry record.
The record does not specify the primary analysis population, the number with an available primary measurement, or how missing measurements were handled. It does not say whether participants were analyzed according to their assigned arm, whether exclusions occurred, or how incomplete visits affected the endpoint. The enrollment listing does not determine the analysis denominator. These details matter because missingness or exclusions can change the composition of the groups being compared and may affect both the estimate and its uncertainty.
The registry also does not report a statistical analysis plan, any interim analyses, or rules for choosing among analyses. Those features should not be inferred from the count of listed analyses. In the absence of these details and numerical endpoint results, readers cannot establish whether the posted analysis matches a prespecified plan, how missing data influenced the comparison, or how to interpret findings across outcomes and analyses.
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 |
|---|---|---|---|
| Control | 0 | 22 | 0.0% |
| Dog Therapy | 0 | 18 | 0.0% |
Deaths
| Arm | Deaths (participants affected of at risk) |
|---|---|
| Control | 0 of 22 |
| Dog Therapy | 0 of 18 |
Other (non-serious) adverse events
Participants with at least one non-serious event at or above the registry's 0% reporting threshold.
| Arm | Participants affected of at risk |
|---|---|
| Control | 0 of 22 |
| Dog Therapy | 0 of 18 |
The adverse-event entries report zero serious adverse events among 22 participants at risk in the Control group and zero among 18 participants at risk in the Dog Therapy group. The entries for other adverse events likewise report zero among 22 at risk in Control and zero among 18 at risk in Dog Therapy. Deaths are recorded as zero in both groups. These are the registry’s event counts for the groups and categories listed.
Zero recorded events should be read as a description of the registry entries, not proof that an event is impossible or that no event occurred outside the reporting framework. The record does not describe the event-collection procedures, follow-up completeness, definitions used, or whether all participants were assessed for the same duration. It also does not identify any serious adverse-event terms. These limitations mean the entries should not be used to make broad claims about safety. They do not provide information about the salivary amylase comparison or answer the study’s primary question.
12. What the Result Does, and Does Not, Mean
The registry record establishes the study’s central comparison: a non-randomized contrast between a group with no therapy-dog exposure and a group introduced to a therapy dog before a dental procedure. It also specifies salivary amylase as the primary continuous endpoint and describes a saliva-collection method and visit-level timeframe. Those details clarify what was intended to be measured, but they do not reveal what the measurements showed.
The numerical primary-endpoint results are not reported in the registry record. There is therefore no basis in these details for stating whether the group means differed, which group had the higher value, how large any difference was, or how precisely it was estimated. The absence of a reported result should not be interpreted as a null finding or as evidence that the groups were similar.
Even with a numerical difference, the non-randomized allocation would limit causal interpretation. An observed contrast could reflect dog exposure, differences between participants, or both. The registry record does not report the information needed to assess confounding or adjustment. A biomarker comparison would also address the recorded biomarker outcome, not every aspect of stress or the experience of a dental visit. The record mentions perceptions of stress in its study description, but does not identify the second outcome measure or give its results.
The listed adverse-event entries record zero events in the reported categories and groups. Those counts are distinct from evidence about the primary endpoint and do not settle broader questions about event ascertainment or interpretation. Likewise, the listed enrollment and completed status do not establish which participants contributed to each analysis. The appropriate reading is therefore limited: the record describes a study designed to assess stress-related measurements around dental care, while leaving the primary numerical comparison and several key analysis details unreported.
13. Why This Trial Matters Statistically
This study raises statistical issues that arise whenever an intervention is evaluated without randomized allocation. The contrast is easy to state—brief therapy-dog contact before a dental procedure versus no dog exposure—but interpreting any difference requires attention to how participants entered each arm and whether the groups were comparable. The registry explicitly warns that the arms are not a like-for-like control comparison. That is an important qualification, not a technical footnote: it limits what a group contrast can establish.
The endpoint also illustrates the distinction between measuring a biological marker and measuring a broader experience. Salivary amylase is recorded as the primary physiologic measure, while the study description also mentions perceptions of stress. The registry does not identify the second outcome or report numerical results for either outcome. Readers therefore need to distinguish the stated aim from evidence about the results.
Finally, a complete statistical interpretation depends on more than whether an outcome is continuous or whether a study is marked completed. It requires numerical estimates, measures of uncertainty, analysis methods, information about missing observations, and a clear account of multiple analyses. These details are not reported in the registry record for the primary comparison. This record is consequently useful for understanding the registered question and design, while also showing why design limitations and reporting completeness must be considered before interpreting an intervention comparison.
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 important limitation for interpreting the primary outcome is that arm-specific means, standard deviations, and a between-arm estimate are not reported in the registry record. Without them, the observed direction, size, and precision of the comparison cannot be described. The record does not report a confidence interval, p-value, or the method used for the primary analysis.
Allocation was non-randomized, and the record cautions that the arms are not a like-for-like control comparison. It does not report participant characteristics by arm, the assignment process, adjustment for potential confounders, or methods for evaluating residual confounding. This restricts causal interpretation. Masking is listed as single, but which party was masked and what information was masked are not reported in the registry record.
The outcome description leaves details about measurement and analysis unclear. The record names a visit-level average over a timeframe described as 60 to 90 minutes, but does not specify the schedule of individual saliva collections or the construction of the average. It does not report the second outcome measure, the eight analyses in detail, the analysis population, missing-data handling, or multiplicity procedures. These omissions impede assessment of whether the analysis fully reflects the planned question.
The registry lists enrollment of 40 and a completed status, but does not state how many participants contributed to the primary analysis. The adverse-event entries are limited to the recorded categories and at-risk groups; event definitions and ascertainment details are not reported. These limitations concern what can be concluded from the registry record and do not establish that unreported procedures or analyses were absent.
15. Related Tutorials
16. Related Statistical Calculators
17. Sources
- ClinicalTrials.gov: Animal Assisted Therapy in Dentistry — NCT04708028.
- Registry record last updated 2024-08-19; status last verified 2024-03.
- Results first posted 2024-08-19.
- 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.
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18. Record Summary
The registry record for NCT04708028 is titled “Animal Assisted Therapy in Dentistry,” with the official title “Animal Assisted Therapy's Effects on Dental Patients.” It lists the sponsor as University of North Carolina, Chapel Hill, a completed status, and a non-randomized, parallel design. The study description concerns physiologic biometrics and perceptions of stress during a dental procedure with or without a therapy dog.
The primary outcome is mean salivary amylase during the dental visit, measured in U/mL. The Dog Therapy arm involved introduction to a therapy dog and permission to pet it for up to 2 minutes before the procedure; the Control arm had no dog exposure. The registry record lists enrollment of 40, two outcome measures, and eight analyses. It does not report the numerical primary-endpoint comparison, the second outcome’s identity and results, or several analysis details needed to assess precision and missing data. Its non-randomized allocation also limits causal interpretation.