The AJO has published a new trial on AcceleDent: Let’s have a critical look at it!
I have posted several times on research into methods of making teeth move faster. This new paper provides us with information on total treatment times with AcceleDent.
Orthodontics is constantly evolving. Recent developments have been methods of reducing the length of treatment. These include, localised trauma, pills and potions, laser light and vibrations. Despite the claims of the manufacturers and those with vested interests, most recent research has shown that there is no evidence that these innovations have a clinically meaningful effect.
Recently, I wrote about a study that looked at the effect of vibration on treatment with Invisalign. This posting attracted a fair amount of criticism on social media. In fact, people accused me of bias, because I was not being critical of research that reinforced my opinions on the introduction of new technology without testing. As a result, I have taken this comment seriously and I am going to take a hard critical look at this paper.
DiBiase et al
Am J Orthod Dentofacial Orthop 2018;153:469-80
I will declare an interest, as I know several members of the study team well.
A team from the Kent in the beautiful South of England did this study.
In their literature review they pointed out that several studies had been done on AcceleDent. Importantly, the first studies were non-randomised, retrospective studies and suggested that AcceleDent had an effect. These were followed by clinical trials that found no evidence of beneficial effect. All these studies were concerned with an evaluation of the stages of orthodontic treatment, for example, rates of canine retraction, alignment and space closure. No studies have looked at the total process and outcome of treatment. I thought that this study was important because they addressed this by asking the following question;
“What is the effect of the AcceleDent appliance on the outcome of fixed orthodontic appliance treatment”?
What did they do?
They did a randomised clinical trial. The PICO was
Participants: People under 20 years old with malocclusion requiring fixed appliance treatment. They had mandibular crowding requiring the extraction of premolars.
Interventions: These were (i) AcceleDent (ii) AcceleDent sham (iii) treatment as usual. They treated all the patients with MBT Victory brackets using routine protocols with approximately 6 weeks between visits.
Outcome: The primary outcome was rate of mandibular space closure. Secondary outcomes were (i) rate of space closure (ii) treatment duration in months and (iii) PAR scoring.
They used timers embedded in the AcceleDent devices to measure compliance. Unfortunately, these failed.
They did a sample size calculation based on rate of mandibular alignment. This was the outcome in an earlier paper on this trial. As a result, this paper reported on outcomes in the absence of a specific sample size calculation. The authors pointed out that the sample size calculation of a previous study of space closure suggested that this part of their study was adequately powered. I will return to this point later, as this is very important.
They did a remote pre-prepared randomisation. They concealed the allocation from the operators. Unfortunately, it was not possible to blind the operators or the patients to their treatment allocation. However, all data was blinded at data collection. It was good to see that they carried out a per protocol and intention to treat statistical analysis. Importantly, this was a relevant regression analysis that took the effect of potential confounders, such as, operator, initial malocclusion etc.
What did they find?
They reported that 81 patients entered the trial and 61 remained at the end of study. This was a 75% completion rate.
They presented a very detailed analysis of their data and I have extracted the important median outcomes into this table.
Mean (mm) +/-SD
|p||Mean difference (mm) (95% CI)|
|1 month||0.67 (0.34)||0.65 (0.26)||0.77||0.02 (-0.13,0.18)|
|2 months||1.28 (0.5)||1.36 (0.49)||0.5||-0.08 (-0.33,0.16)|
|3 months||1.88 (0.67)||1.93 (0.74)||0.76||-0.05 (-0.4,0.29)|
Their extensive statistical analysis revealed no difference between the groups for any of the outcomes.
They pointed out that the rates of space closure and duration of treatment was similar to other studies.
Finally, they drew attention to the limitations of this study in the discussion.
What did I think?
As with all trials there are strengths and limitations. We need to remember that the main advantage of trials over other study designs is that bias is minimised. Importantly, it is not possible to remove all bias and do the perfect trial. It is, therefore, up to us to interpret all studies in the light of any limitations.
What were the strengths?
Firstly, I will look at the strengths. The most important was that this was a multi-centre trial done with multiple operators in clinics working to normal protocols. Randomisation, allocation and concealment were all good. They collected the data blind. They carried out a relevant and sophisticated data analysis. The authors were not funded by OrthoAccel. Finally, the AJO-DDO published the paper and this is our leading orthodontic journal with a reputation for high quality.
What were the limitations?
The authors drew attention to the limitations of their study. I felt that the most important was the sample size calculation. They did not base this on the outcomes that they measured in this part of their study. This means that there is a risk that the study did not have sufficient power to identify any statistical significance between the groups. They did use calculations from other studies, to justify their sample and this was reassuring. However, we also need to consider the effect size of the interventions. This was small. As a result, I am fairly confident in their findings.
Another issue is that the compliance timers did not work. In face, some AcceleDent Key Opinion Leaders raised this as a criticism of the study. My feeling is that while it would have been useful to have data on compliance, this is not essential. This is because the study was measuring the effect of giving a patient an intervention to use. This is similar to a drug trial in which investigators prescribe a self-administered drug to participants in the study. We do not know if they take the medicine. Importantly, this is what happens in the real world and these trials have validity.
The other limitations were less important and the randomisation minimised their effects.
We need to consider the results of this study with respect to other RCTs. There have now been several and they are all coming to the same conclusion. There is an absence of evidence of a clinically meaningful effect of AcceleDent on tooth movement.
Emeritus Professor of Orthodontics, University of Manchester, UK.