A new consensus study shows us what aligners can do?

Clear aligners are a central component of orthodontic care. However, recent research shows they do not offer the same level of control as fixed appliances. Paradoxically, many practitioners recommend them as an alternative to fixed appliances. Strangely, despite its popularity, there is limited prospective research on this treatment option.

This means that our knowledge of the use of clear aligners is somewhat limited. This study team attempted to address this situation by conducting a study to reach consensus on the utility of aligners.

A team from Naples and Florence did this research.  Progress in Orthodontics published its paper. This paper is open access. Anyone can read it.

What did they ask?

They wanted to:

“Offer clarity on the role of clear aligners in contemporary orthodontics and to identify further areas of research”.

What did they do?

The team carried out a Delphi consensus study.  The aim of this type of study is to use a systematic method to develop consensus about a problem. There have been very few studies of this nature in orthodontics.  These studies involve several stages. These are:

• Establish a study steering committee.
• This group identifies the current evidence concerning a treatment.
• Then identify important topics.
• Construct a series of statements.
• Identify a larger group of experts to form a study panel.
• They then circulate the statement to the panel and ask them to rate their agreement or disagreement with the statement.
• If there is no “agreement”, they circulate the statements to the panel again with the overall scores that were given. The panel then rescores. They continue this process for another session until they reach an agreement/or don’t agree on the statements.

This requires a large amount of effort and careful coordination by the team.

This study team followed this method. 

They provided extensive detail on this in their paper, and I will not elaborate here, as you can read the paper. However, I want to highlight what I believe to be the most important feature of their method.

• The steering committee conducted a literature search to identify subtopics in aligner research. They prioritised systematic reviews and RCTs. However, if they did not find these studies, they included prospective or non-randomised studies. The aim of this search was to identify gaps in the evidence and select at least one high-quality study per subtopic.
• The steering committee then compiled a list of statements which they sent to the expert panellists.
• One of the principal investigators identified a panel of 30 orthodontists who are authors of peer-reviewed publications and/or international speakers on aligners.

What did they find?

They reported 21 statements on clear aligners.  I do not have the space to report on all of these. However, I thought that these were the most important.  I have pasted these directly from the paper.

Efficacy and efficiency of clear aligners

• Treatment with clear aligners is an effective alternative to conventional fixed appliances in Class I non-extraction compliant patients with mild to moderate crowding.
• Treatment with clear aligners is an effective alternative to conventional fixed appliances for managing open bite cases
• Expansion with clear aligners is achieved primarily through crown tipping rather than bodily tooth movement
• The degree of root resorption is lower with clear aligners compared to conventional fixed appliances, although the level of evidence is low

Side effects of clear aligner treatment

• The degree of root resorption is lower with clear aligners compared to conventional fixed appliances, although the level of evidence is low
• White spots and carious lesions are less frequent in patients treated with clear aligners compared to those treated with conventional fixed appliances

Clear aligners in growing patients

• Treatment with a rapid palatal expander produces more skeletal expansion with  less dental tipping than treatment with clear aligners 
• There are no differences in the skeletal changes achieved in Class II patients treated with either clear aligners featuring a mandibular advancement device or traditional fixed and removable functional appliances, although the level of evidence is low

Clear aligners and extraction treatments

• In patients with Class I molar relationships and severe crowding, treatments requiring the extraction of four first premolars achieve less favorable alignment outcomes with clear aligners compared to conventional fixed appliances. 
• There is also greater tipping movements of teeth compared to conventional fixed appliances.

What did I think?

This was a very interesting paper that reported on an unusual study for orthodontic research. 

Firstly, I want to highlight the strong points of the research. The team used a standardised Delphi methodology effectively, and they wrote a clear paper. The panel and study teams were sufficiently large to reach a consensus on quite complex statements. The statements were clear and logical.

I have also examined potential biases inherent in the methods closely. I found several that warrant consideration. Firstly, I was uncertain about how they identified members of the expert panel. They used a reasonable approach, but I was not clear on the specific criteria used to identify each member as an expert. I am not suggesting that the members were not experts; it would be useful see more detail on their selection process.  

I am also aware that there was a risk of recruiting some well-known KOLs who feel that they are experts in aligners.  It was good to see that they did not select this group.

Secondly, due to the limited research on aligners, the quality of the evidence they had to depend on was mostly of low standard. I looked closely at the papers they selected for circulation to the expert panel. These included six systematic reviews, one prospective cohort, five retrospective studies and only two RCTs.

Quality of evidence

I then looked at the systematic reviews. These reviews included analyses of retrospective and other low-level studies. For example, this review encompassed 18 systematic reviews, and the authors noted that “18 SRs, 3 (16.66 %) had moderate-quality evidence, 8 (44.44 %) were of low-quality evidence, and 7 (38.88 %) were classified as critically low-quality evidence”

As a result, the “white noise” of poor quality systematic reviews may obscure any conclusions. We all know this is a current problem in orthodontic research, where some investigators only conduct systematic reviews and become recognised as experts.

This leads me to conclude that the panel’s statements are based on limited evidence and their own clinical experience. As I have discussed before, these are two important components of evidence-based care. As a result, the statements reflect the current limited understanding of aligner treatment.  

Final comments.

I would like to point out that I am not being overly critical; I am simply addressing challenging aspects of this form of research. I commend this team on their scientific approach to reaching a consensus that appears logical and reflects the current state of research into clear aligners.

Almost the last chance to help me do something good for once?

Hopefully, this is the last time that I will use the blog for this plea. Your response for donations to support our walk raising funds for Maggie’s Cancer Support Centres has been fantastic. I set a target of £5,000, and readers of this blog have donated £4400. I would really like to hit our target. If 60 of the thousands of people who read this blog donated £20.00, we would achieve our ambitious aim.

If you haven’t donated and feel you can help us, please read on and make a donation for our walk.

I am raising funds for Maggie’s Cancer Support Centres. I will be walking 22 miles across the U.K. moors in memory of my dear friend Dr Betsy Bennett. Sadly, she passed away from leukaemia at only 61. I want to honour her by using the power of this blog to raise a substantial amount. If everyone who reads this blog donates £5.00, we will raise an amazing amount! The donation button is at the bottom of this section.

Betsy was a psychologist. We collaborated in Pittsburgh and North Carolina. Her kindness and personality touched everyone she met. She introduced me to research on patient and psychological outcomes, which changed my research direction. I’m so grateful to have known her. 

What is Maggies?
Maggies is a fantastic charity. There are 24 centres in the UK, welcoming 100+ visitors into each centre every day. I volunteer at the Manchester Centre.

The centres offer free practical and emotional support to anyone whose lives are affected by cancer. They depend entirely on charitable donations and concentrate on issues such as financial worries, housing, stress management, treatment side effects, and family support. They provide this support through one-on-one sessions or group discussions. 
It would be wonderful to provide them with substantial support to help them sustain their incredible work.