May 11, 2020

Do Clear Aligners reduce demineralisation?

Demineralisation and white spot lesions (WSL) are a common consequence of fixed appliance treatment. WSLs result from poor oral hygiene around the appliances.  Because Clear Aligners (CA) are more hygienic than fixed appliances. It may be suggested that there may be less WSLs with clear aligners than with fixed appliances. However, there has been limited research into CA treatment. This new trial looked at the development of WSL with CA and FA treatment.

A team from Irbid, Jordan did this study. The AJO-DDO published the paper.

What did they ask?

They did this study to answer this question:

“Is there any difference in white spot lesions between clear aligners and fixed appliances”?

What did they do?

They did a randomised controlled trial with a 1:1 allocation.  The PICO was


Orthodontic patients aged between 17-24 years with Class I moderate crowding treated on a non-extraction basis. Their oral hygiene was good.


Clear aligner treatment


Fixed appliance treatment


Primary outcome: Average white spot lesion (WSL) fluorescence loss measured with QLF. Secondary outcomes: Surface area of WSL, deepest point and incidence of new lesions.

They collected fluorescence images of the maxillary and mandibular anterior and premolar teeth at the start of orthodontic treatment and after three months of treatment.

They randomised the patients to the two interventions by tossing a coin. Unfortunately, they did not provide any information on allocation concealment. They could not be blinded for the recording of the data from the images.  However, they were blinded for the data analysis.  They did a sample size calculation that I thought was clear.

What did they find?

They enrolled 49 participants in the study. These were divided into 27 in the CA group and 22 in the FA group. Four of the CA and 3 of the FA group dropped out of the study. They did not analyse the data for these patients.

They clearly published their data. There was no difference between the groups at the start of treatment.  I am only going to report and discuss the differences between the groups at the end of the three-month data collection period.  I have extracted the relevant data into this table.

Fluorescence loss(%)Max Fluorescence loss(%)Lesion area (Pixels)
Clear aligner-7.7-13.7149.2
Fixed appliance-9.1-16.768.7
Difference (p value)1.4 (0.002)3.0 (0.039)80.6 (<0.001)
95% CI-1.8 to -0.4-4.0 to -0.4-117 to -75.0

When they looked at the incidence of new lesions. They found that the CA group developed 143 and the FA group developed 165 new lesions. This was statistically significant.

Their overall conclusions were

“Orthodontic treatment with CA and FA resulted in enamel demineralisation.  The CA group developed larger but shallower WSL. But the FA group developed new lesions with greater severity but were smaller in area”.

What did I think?

This was a good small study.  The authors wrote it up well and it was very clear.  They reported a relevant amount of data. The randomisation generation, sample size calculation, description of blinding, and statistical analysis was clear.  I spotted that there was an imbalance between the size of the groups, and this was probably a result of using a coin-tossing allocation. This may not have occurred if they had used randomisation that would ensure that the groups were balanced. Nevertheless, the difference between the group sizes was small. Importantly, there were no differences in baseline characteristics between the groups.

I thought that the results were interesting and logical. The authors discussed these well. They pointed out that the differences in demineralisation were probably due to the nature of the treatments. For example, the clear aligner attachments were larger than the fixed appliance brackets. This resulted in a larger area of demineralisation for the aligner group.

Their overall conclusions were clear.  The use of aligners does not avoid demineralisation, however, there are differences in the nature of the demineralisation from fixed appliances.

Final comments

As with all studies, no study is perfect. I have several concerns. The first is concerned with whether the amount of decalcification is clinically significant. While QLF is a precise technique, I would like to know if the lesions were visible under normal viewing conditions. Futhermore, I was concerned that it was not possible for the investigator to be blinded to the intervention when they analysed the images. This is because the appliances were still in place.  This is a clear source of bias and we need to be cautious when we interpret their results.

Finally, the duration of the study was only three months. I wonder if these findings are relevant to the conclusion of treatment. I hope that the authors can consider publishing this data when the trial is finished.

Nevertheless, I thought that this was a nice study that provided us with clinically relevant information. Importantly, this showed that using clear aligners does not avoid demineralisation.


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Have your say!

  1. Hopefully they’ll follow up with an analysis at the end of treatment. I don’t see how data collection could be blinded if they were still under treatment, unless they removed all appliances and attachments at three months? Could you clarify?

  2. Interesting. Bushang published an article in 2018 in the Angle Orthodontist on this same subject. The conclusion was « Patients treated with aligners have less risk of developing WSLs than do patients treated with traditional braces, which could be partially due to shorter treatment duration, or better pretreatment OH»
    I think we can compare these studies to root resorption. Let me explain… I do a lot of clear aligners treatment (since 2004) and don’t start new fixed appliance cases anymore (I finish the ones I have) and I remember hearing a couple of speakers claiming there was never any root resorptions with clear aligners!!! Well, like the saying from Laplace, made popular by Carl Sagan: «Extraordinary claims require extraordinary evidence». Logic should tell us that there is no way clear aligners can prevent WSL or RR. Teeth and supporting structures are not selective and do not decide how they will react to different appliances. It is reasonable to think that maybe because of the fact CA treatments are shorter in time than FA treatments (ex: Bushang again, Comparative time efficiency of aligner therapy and conventional edgewise braces published in 2013 (!!!) in the Angle Orthodontist) we should see less WSL and less RR in patients treated with this technique. But, a force is a force and hygiene is hygiene. CA and FA are not causing WSL: lack of hygiene is. My clinical opinion is CA have tremendous advantages over FA (they are not perfect, nothing is!) but it would be false to claim that our patients have no risk of developing WSL with them. Part of our role and our team’s role is to educate them to the fact that hygiene is more important than ever as their teeth are covered almost 92% of the time. To give them an image we compare it to a bandaid on a finger for a couple of days. We tell them to picture how the skin is when they remove it. And we explain this is what will happen if they don’t keep a good (excellent!) hygiene during treament. Yes you can use it 😉
    Be safe everyone!

  3. Personally, I feel a 3 month study is pretty irrelevant. Poor brushing can sometimes be from day one, but more than often, it is a ‘learned’ habit (or lack thereof). The longer treatment goes, the worse hygiene becomes, just as elastic wear diminishes. Patients get tired and burned out. I would hope we see hardly any white spot lesions at 3 months. If we do, they probably were poor brushers before they ever even started treatment.
    Our practice is about 60% fixed appliances and 40% clear aligners, with that ratio getting closer to 50/50. I have to say, in my experience within my practice, there is no comparison in the number of WSL between the two. Fixed appliances have a far greater number of WSL incidence than clear aligners in our practice. I have not done a study, but I do know how often I have conversations with patients and parents regarding post treatment WSL.

  4. Thanks Kevin and Stephane.
    Yes, I hope that the study continues to post deband and attachment removal stage, with blinding of the researches collecting the data . That way we may have data that more accurately reflects the post treatment condition of enamel, although additional variable of deband / attachment removal technique may further confound data reflecting demin lesions.
    Anecdotally I observe a higher standard of oral hygiene maintenance in my CA patients and my bias leads me to believe that this would place FA patients at higher risk of demineralization; however, my major reason for posting today is to share an experience with a CA patient who imbibed sports drink over her aligners. She was an avid netball player and believed that this was a healthy, innocuous beverage. Literally from 1 appointment to the next (6 weeks) she developed significant white spot lesions around the cusp tips and incisal edges. (different pattern to what we may observe in FA cohort). Detecting this was one of my darkest days as a clinician. Thankfully between use of nightly tooth mousse in her aligners and a vigilant general dentist, damage was mitigated. My conscience, along with her enamel; however, will never be fully repaired. From that patient onward, my verbal and written delivery and monitoring visit reinforcing instructions include not only the generic “nothing but water when aligners are being worn” but adding ” including no sports drinks, soft drinks (soda for the US audience) or juices” to adults and teens alike. In that way I remind myself most days of Louise and the iatrogenic damage that could have been avoided……..

  5. “…..1 appointment to the next (6 weeks) she developed significant white spot lesions…”
    Sorry to be off topic Kevin but do you think this patient (Louise) would have had a happy ending undergoing DIY treatment? I may be wrong but somehow I think there is just a LITTLE (note sarcasm) value in having a clinician in a traditional office setting monitoring the progress of a case on a regular basis.

  6. I personally believe that in non-compliance patients (poor brushing) , it is almost the same risk of developing WSL in both CA and FA cases. I am afraid it might be even worse with CA patients who don’t clean their Alingers properly !

  7. Dear Kevin.. Many thanks for your notes and good critique on our paper ..
    Re: blinding, unfortunately it is just not possible to do it .. because the appliance just shows in the picture so it can’t be blinded !!
    Re: short period follow up .. the initial plan was 6 months but it took longer time than planned to collect the patiens. Ziad was a master student and he had limited time according to the university regulations.. so we finished after the first reading which was after 3 months
    We have a series of studies with longer term follow up on white spot lesions in relation to Orthodontics using QLF .. hopefully they will be published in due time
    Susan Al-Khateeb

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