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.
Ziad Albhaisi, Susan N. Al-Khateeb, and Elham S. Abu Alhaija
Am J Orthod Dentofacial Orthop 2020;157:594-601. https://doi.org/10.1016/j.ajodo.2020.01.004
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)|
|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.
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.
Emeritus Professor of Orthodontics, University of Manchester, UK.