Aligner treatment with and without Dental Monitoring; Does it work?
One of the recent developments in aligner treatment is Dental Monitoring. This system is a method of remote monitoring of orthodontic tooth movement. But does it “work”?
When a patient uses Dental Monitoring, they scan their teeth using a smartphone. They then upload their pictures to a company server. The company then uses algorithms to view individual tooth movement and prepares a treatment dashboard to show the progress of treatment. In the third component of the system, the orthodontist views the treatment dashboard. In this way, the orthodontist can monitor the treatment remotely. There may be advantages in terms of reducing attendances and treatment time with the new technology. Theoretically, this looks a really good development.
A few months ago, I did a blog on a retrospective study that looked at Dental Monitoring’s effects on Invisalign treatment. I thought that this paper was an interesting first step in evaluating the impact of Dental Monitoring. Importantly, the only effect of DM was to reduce the number of appointments by 2.26.
Therefore, I was very interested to see the same team publish a paper on the same subject using the same methodology. I thought it was worth looking at this “second step” in research into this technology.
A team from Dubai and Sydney did this study. The AJO published the paper.
A retrospective cohort study
Ismaeel Hansa, Vandana Katyal, Donald J. Ferguson, and Nikhilesh Vaida
AJO: Advanced access. https://doi.org/10.1016/j.ajodo.2020.02.010
What did they ask?
They did the study to find out information on;
“The effects of Invisalign with and without DM treatment on treatment duration, number of appointments, number of refinements, number of refinement aligners etc.”.
What did they do?
They did a retrospective study of patients treated by a specialist orthodontist in Sydney. A Dubai based IRB approved the ethics of the research. I am not sure how this approval was used in Australia as the authors did not provide any details.
They did a power calculation from the results of a pilot study. This calculation resulted in a total sample size of 48. However, they increased the sample size so that they could look at other effects of treatment. They did this in their other study. I am not sure why they took this step because they are at risk of overpowering the study. Anyway, they doubled the sample size to study a sample of 59 DM and 56 control patients.
This research was another retrospective study. The orthodontist offered Dental Monitoring to all the patients at the start of treatment. They instructed both the groups of patients to change their aligners every seven days. The DM group was scheduled for appointments at 16-week intervals, and the control group was seen every 6-8 weeks. They gave no information on why the control patients did not receive Dental Monitoring.
There were many outcomes. These were; treatment duration, number of refinements, number of refinement aligners, time to the first refinement, number of appointment and number of emergency visits. They also measured the accuracy of achieving the treatment outcome by superimposing the start and the refinement/or complete treatment scans.
What did they find?
There were no differences between the groups at the start of treatment.
When they looked at the treatment data, they found two statistically significant findings. These were that the time to the first refinement was significantly shorter in the DM group by 1.7months. They also showed that the mean number of appointments was 3.5 visits less than the control.
They also stated that they found differences in the other variables, but these were not statistically significant. I am not sure why they stated their results in this way. If a difference is not statistically significant, then it may have occurred by chance. They also did not state the p values. As a result, this was a very confusing section to read. I was surprised to see such basic errors in the AJO.
There were no differences in treatment duration. DM was 12.2, and control was 14.0 months.
Notably, there were no differences in the accuracy of achieving the treatment outcome.
- DM significantly reduces the number of office visits by 3.5 attendances.
- DM reduced the duration of treatment to the first refinement by 1.7 months.
- There was no difference in overall treatment duration.
- The DM group achieved clinically similar accuracy to the control group in 1.7 fewer months. This finding indicates improved aligner tracking.
What did I think?
I have previously stated that I rarely review retrospective studies. This is because they suffer from selection bias, and their findings generally do not change practice. However, I will include some papers if they look at a controversial area or a potentially useful new development. As a result, I decided to look at this paper.
I was very interested to see that the methodology was similar to the paper that this group previously published. It was, therefore, no real surprise that the results were similar. In the other study, the only difference that they detected was that DM resulted in a reduction of 2.5 appointments.
Significant flaws in the study?
I need to point out that this study suffers from many problems that are due to the research method and reporting. These are:
- It is overpowered, leading to minor effect sizes being statistically significant, yet, not clinically significant.
- They provided no information on why one group of patients got DM and the other did not. This leads to a significant risk of bias.
- They only looked in detail up to the refinement stage. This was about 6-7 months of treatment. I would like to see information on the completion of treatment. This data must have been available as this was a retrospective study.
- The decision to carry out refinements is subjective, and as the operator was not blinded, the study is subject to high levels of bias.
- I also wondered how a difference in time to refinement occurred if both groups changed their aligners every seven days. Unless they recalled the DM group for refinement earlier. This is why blinding is essential. This problem invalidates their final conclusion above.
- I was concerned that the authors did not reference this paper in the paper that appeared in the Progress in Orthodontics, particularly as the methodology and results were very similar. Unless this was an oversight.
- I was also not sure if there is a conflict of interest for one of the authors. I have spotted that they are a speaker for Dental Monitoring at their online seminars and on Facebook. Perhaps, they should have declared this to the Journal?
- An ethical (IRB) committee based in Dubai approved the study and it was carried out in Australia. I would have liked to see how the Dubai approval was transferred to Australia.
Dental Monitoring maybe a significant development in orthodontics. However, both of these papers suggest little gain from this new technology. I would like to see some data on the amount of time the operator has to spend reviewing monitoring. But importantly, we need to see information on the final results of treatment. The research findings are still disappointing.
Emeritus Professor of Orthodontics, University of Manchester, UK.