The need for speedy orthodontic treatment: Low level laser light therapy makes teeth move faster: Or does it?
The need for speed: Low level light therapy makes teeth move faster: Or does it?
It’s great to see that several studies are now being published on the new methods of making teeth move faster. The Angle Orthodontist recently published this new study. It is about the effects of low level laser light therapy on the speed of tooth movement.
Low-level laser therapy effectiveness in accelerating orthodontic tooth movement:
A randomized controlled clinical trial
Mohammad Moaffak et al
Angle orthodontist: Published on line. DOI: 10.2319/062716-503.1
The authors stated that their study was the first published randomised trial that evaluated the effects of laser light therapy on tooth movement. Importantly, other studies have either not been trials or they have been small-scale pilot studies.
What did they do?
They carried out a two arm parallel group randomised controlled trial. Their PICO was
Participants: Orthodontic patients aged between 16 – 24 years old with a Little’s irregularity index of 7 mm or more in the maxilla. The treatment required the extraction of two premolars.
Intervention: Laser light therapy throughout levelling and alignment
Comparison: Untreated control
Outcome: Time to complete levelling alignment. With a secondary outcome of the percentage of levelling and alignment.
This was a small scale study in which they randomised 26 participants to the two interventions. They selected the allocation by taking a folded piece of paper from a box. The author generated the sequence, enrolment and assignment.
They carried out a sample size calculation based on a 40% reduction in levelling and alignment. This was roughly a difference of 97 days.
The lead author applied the laser light therapy immediately after inserting the first wire. They repeated this on days 3, 7 and 14 and continued every 15 days starting from the second month.
The endpoint of the light therapy was when the Little’s Irregularity Index was less than 1 mm. It was not clear who made this assessment and whether this was done directly in the mouth or on study casts.
They collected the data by taking an alginate impression at the following time points;
T0: Before arch wire insertion
T1: After one month
T2:After two months
T3: At the end of levelling alignment
They cast the alginates and made measurements with a digital caliper.
They carried out a simple data analysis by using a ’t’ test.
What did they find?
They found that the use of low level laser therapy reduced the time taken for orthodontic levelling and alignment. In effect, light therapy reduced the treatment time by 28 days. They calculated that this was a 20% reduction in the time of this phase of treatment. They presented this data in a table that did not contain Confidence Intervals. I have inserted them into the table below.
|Anterior Arch perimeter (mm)||Little's Irregularity Index (mm)|
|Baseline||After 10 weeks||Baseline||After 10 weeks|
|Differences||0.6 (-1.6, +1.8)||-0.1 (-1.5, +1.1)||-0.5 (-2.2, +2.8)||0.2 (-0.6, +0.6)|
They concluded from the results of their study, that low level laser therapy is an effective method for accelerating tooth movement.
What did I think?
I think it is important that high quality studies should measure the effectiveness of new treatments. This is because these methods tend to involve additional cost. For example, there is additional surgery time and direct cost for the patient. In this respect, I would hope that submissions of papers are subject to high levels of scrutiny by the academic journals.
I was, therefore, rather disappointed to find several important issues with this paper. These weaken the strength of their conclusions and I am surprised that the Angle Orthodontist published this paper. These are:
- The mean age of the participants in the laser group was 18.53 (SD = 2.9) years. The control group were older at 21.6 (SD equals 2.6) years. I calculated this to be a statistically significant difference.
- There was also a greater Littles Irregularity Index in the control group (10.9) than the laser group (8.9) This again was statistically significant.
- As a result, the control group was older and had more crowding at the start of treatment than the laser therapy group. The groups were different,at the start of treatment. I wonder if this had influenced the results?
- They did not blind the operators in the study to the treatment allocation. Importantly, they did not make it clear if the assessment of the endpoint was done by someone who was blinded to the allocation. This means that the study may be at high risk of bias.
- The small sample size resulted in wide 95% confidence intervals. This meant that there was a high degree of uncertainty in the data.
I also think that we need to consider the burden of care to the patients in this technique. The patients had to attend the clinic several times to have the laser light therapy. We must not forget that this attracts direct costs for the treatment and indirect costs to the patients i.e. time off work or education. We need to consider whether these costs are worth the reduction in treatment time. In this respect, studies of these new interventions should include some form of cost/benefit appraisal.
As a result, unfortunately I cannot agree with the conclusions of the study. We still do not know if low level laser therapy works…..
Emeritus Professor of Orthodontics, University of Manchester, UK.