What did they ask?
They did this systematic review to ask.
“What is the effect of non-surgical adjunctive interventions on the rate of orthodontic tooth movement and the overall duration of treatment”?
What did they do?
The team carried out a systematic review to Cochrane standards. Firstly, they did electronic and relevant additional searches of the literature. This was followed by identifying relevant papers, assessing the risk of bias with the Cochrane Risk of Bias tool, evaluating the certainty of evidence with the GRADE tool, data extraction, and meta-analysis.
They confined the search to randomised controlled trials. Notably, they excluded split-mouth designs.
The PICO was;
People of any age have orthodontic treatment with fixed or removable appliances.
Any non-surgical intervention to accelerate tooth movement.
Any form of orthodontic treatment without using non-surgical interventions.
The primary outcome was the duration of orthodontic treatment. Secondary outcomes were the number of visits needed, rate of reduction in arch alignment, rate of orthodontic tooth movement in mm/month, and improvement in occlusion.
What did they find?
This was an update of a Cochrane review that they did in 2015. At that point, they identified only 2 studies for inclusion. In this update, they found 41 records that reported on 23 studies. These were all parallel-group RCTs. Fourteen studies compared two groups, eight looked at three, and one compared four groups.
The trials included 1027 participants with an age range from 8 -50 years. Most studies involved fixed appliance treatment, and three evaluated clear aligners.
Helpfully, the team classified the interventions into two categories: light vibrational forces and photobiomodulation (Low-level laser therapy and light-emitting diode). Twelve studies looked at vibration, 10 evaluated low-level light therapy, and two studied light-emitting diode therapy.
When they looked at the risk of bias, they found that no study had a low risk of bias in all the domains. I felt this was primarily because of the lack of blinding of the operator and participants. There were other concerns with the lack of blinding of the outcome assessment and selective reporting. This meant that the overall certainty of the evidence was low.
They provided a large amount of data on the nature of the papers, the interventions, the control, and the many outcomes they evaluated. I will choose the outcomes that I feel are relevant to my practice. These are the treatment duration, outcome, complete alignment, and participants’ perception of pain and discomfort. This is what they found.
There was no evidence that the duration of orthodontic treatment was reduced or increased by applying vibratory forces compared to a control. The mean difference was 0.6 months (95%CI=-2.44 to 1.22). (Two studies with 73 participants). Low certainty evidence.
Similarly, there was no evidence that the number of adjustments was increased or decreased.
When they looked at the rate of tooth movement during alignment, they used the information from 4 studies involving 221 participants. They found no differences and suggested that.
“the available low certainty evidence does not support the use of vibration in increasing the rate of orthodontic tooth movement”.
There was no evidence that vibration influenced the perception of pain.
Similar conclusions were drawn for all the other outcomes.
Low-level light therapy and LED.
No study reported the effect of this intervention on the total treatment duration.
Four studies with a high risk of bias reported shorter alignment duration. The mean difference was 48.5 days shorter with light therapy. It also appeared that this reduced the number of visits by 2.25 visits. This was very low-certainty evidence,
There was no effect on pain perception.
Their overall conclusions were
“From the evidence available there was no evidence of benefit from the use of vibrational forces or photobiomolation on the reduction of treatment duration. However PBM may reduce the length of the early stages of treatment and increase the speed of tooth movement”.
“Studies that evaluate the effects of these interventions on the total duration of treatment are needed”.
What did I think?
This was a highly detailed and well-produced systematic review that was done according to the very high standards of the Cochrane Collaboration. As a result, it is an excellent addition to the literature.
As with other Cochrane reviews, the included trials are at high risk of bias. This is because orthodontic trials do not blind the operators. However, it is almost impossible to achieve this in orthodontic trials. As a result, I take a pragmatic approach when I read orthodontic Cochrane reviews and I am not too concerned if this is the only reason for the allocation of high risk of bias.
The most compelling information this review reveals is a lack of evidence for the claimed effects of the vibratory devices. Furthermore, when we look at light devices, the effect sizes are small, and we do not know if this makes a difference to the complete course of treatment. Which, of course, is the most important outcome measure.
My other conclusion is that at the end of all this, some practitioners, companies, and their KOLs made considerable amounts of money from these interventions. Unfortunately, their claims were then accepted by non-critical orthodontists. Now that investigators have done the trials, we know that these developments are simply unfulfilled hopes and dreams.