What Does Recent Research Tell Us About Aligners?
Over the past two years, I’ve written several posts about research on clear aligners. Now, I’ve decided to summarise the findings in one post to help you form your own conclusions on their effectiveness.
These are the posts and the main conclusions.
Is a 2×4 appliance better than aligners for mixed dentition crowding treatment?
This study is important for those providing interceptive treatment for maxillary crowding and considering aligner treatment for children. It shows that aligners are as effective as 2×4 fixed appliances. Thus, making the advantages of invisible appliances available to younger patients.
At last, a trial on aligners v fixed appliances in complex cases!
This study showed that orthodontic treatment with aligners is comparable in terms of occlusal index scores with fixed appliances. It is a good and valuable study.
Back to basics: clinical outcomes with aligners versus fixed appliances
This was a summary post by Martyn Cobourne. He came to several conclusions. The most important one was that aligner treatment is effective for mild to moderate malocclusion requiring simple tooth movement. Nonetheless, it is less effective than fixed appliances for more severe crowding and complex cases.
Do plastic aligners cause harm?
This paper discusses the research on the potential negative effects of plastic materials. Although it may seem a quantum leap to connect plastic aligners to environmental harm. It is important for us to consider these potential risks, as we do not really know the long term of our increased use of plastics.
A new study shows how aligners close anterior open bite.
Aligners are an effective method for treating AOB, and the correction be stable. When we consider treatment effects, aligners seem comparable to fixed appliances with TAD support.
Expansion with aligners or rme. What is better?
In this group of patients, it seems that both CAT and RME are effective. When deciding on a treatment method, it’s important to consider patient preferences and cost. Currently, it seems that CAT is more costly than RME. As a result, I am inclined towards the traditional choice, which requires less patient cooperation. Still, there is increasing evidence supporting aligners as a feasible treatment method.
A new study shows invisalign mandibular advancement is not effective
This study showed that MAA treatment couldn’t adequately reduce overjets.
Which is better for class ii problems, herbst or invisalign mandibular advancement?
This was another study suggesting that the Mandibular advancement appliance reduced overjets by only a small amount.
Has invisalign advertising “crossed the line”?
Yes, it did!
Final thoughts
When I reviewed these posts again, I realised that a lot of research is being done on aligner treatment. Still, I couldn’t help but feel disappointed that most of these papers were retrospective studies. Retrospective studies always include selection bias, which reduces our confidence in the findings. It’s time for someone to conduct some trials on this treatment.
Nonetheless, despite these findings, I am under the strong impression that aligners are valuable for treating simple issues in adults who do not want to wear visible appliances. I am far from convinced that they are an alternative to traditional appliances for children.
In some ways, their effectiveness is comparable to the results achieved with basic removable spring-type appliances during the early days of orthodontics. Or perhaps I’m just an outdated academic who fails to recognize the benefits of this treatment method and can’t let go of fixed appliances.?
Finally, I also have some concern about the environmental effects of plastics. We should all attempt to reduce our use of plastics, yet orthodontics appears to be increasing plastic use. We do have to take our responsibility for future generations seriously.
i look forward to seeing more research on this treatment.
Thanks Kevin. As I write this, I am examining a paper on “accuracy’ of aligner treatment. Perhaps a slight improvement on the similarly abused term ; “predictability”. Thank-you for using more appropriate terminology. We do need to learn more about the “effectiveness” and “efficiency” of computer programmed aligner systems used to treat our patients – ALL of them.
Interesting observation that when you refer to “favorable” findings above, the experimental variable is “aligner treatment”, and when the findings are unfavorable, you name the product- even when it is not used in the title of the paper being reviewed. A note: that all of the papers mentioned above, including the majority that do have positive findings are investigating…. the Invisalign system.
Plese indulge me while I list my other major annoyance:
CAT (Clear aligner treatment) is a generic grouping that does not differentiate materials, manually programmed systems (that still exist in the market) versus computer programmed aligner systems versus Invisalign System aligners programmed to be force driven, as opposed to all others that are displacement driven. And yet we continue to lump all aligners together and apply research findings to all “aligner systems”. Can we please be more specific, especially when interpreting and applying (or not) literature findings? May other aligner companies please step up and publish …something? May we demand to have external objective evidence prior to using an aligner system that has zero, even if they produce nice brackets? Even case reports would be a start. We know the Invisalign system may be equivalent- in terms of occlusion and alignment outcome -of mild to complex malocclusions to that of some fixed appliances (still want the benchmark studies for fixed we are referring to). We have no idea about efficacy of ANY other aligner system- internal nor external. To ride on coattails and attempt to imitate instead of innovate is boring, an insult to our specialty, who somehow have come to accept that all aligners produce similar outcomes; that only 1 product needs to be researched – and those of us who are parsimonious gleefully accept this deception, possibly in lieu of our patients’ wellbeing.
In light of this, I respectfully believe that your blog should be re-titled “what does recent research tell us about the Invisalign System?”
– Totally agree regarding environmental effects, pitfalls of overconfident marketing claims as well as the need for more prospective studies. Meantime, choose wisely!
VV* provides sponsored lectures for Align Technology
The fundamental problem with removable appliances, including Clear-Alignres, is the orthodontist’s inability, in any situation, to control the tooth’s center of resistance (Cres) location. In removable appliances, the Cres location depends on the periodontal ligament (PDL) and the alveolar bone surrounding the tooth, referred to as the biological natural restraint. No one knows precisely where this point is located, especially during treatment, as its position changes due to biological factors and force level application.
The Cres, the equivalent of the physics-related center of mass, is far from a permanent point in the tooth.
What happens if the tooth becomes ankylosed at the apex zone?
It is clear that the Cres immediately shifts from somewhere at the center of the root to the ankylosis area at the apex. This fact requires no research, as it is an irrefutable physical fact.
What happens when we bond fixed appliances to the teeth’s crowns? Does it change something in the system?
The answer is positive. Fixed appliances, following bonding, change the tooth to develop a new body due to the artificial restraint that is 1000 times stronger than the natural (alveolar bone and PDL) restraint. In this case, the bracket attached to the wire becomes like an ankylosed point, shifting the Cres, which serves as well as the center of rotation of a tooth, from the root to the crown.
Since the Cres can move to the crown, every vector applied to the tooth that does not pass through the Cres will rotate around the Cres, meaning the apex moves much more than the crown’s edge, in a different direction (the Andrews’ real torque movement definition).
As can be seen in several studies, drawing two equal arrows in opposite directions in different planes on the crown figure, does not and cannot develop a couple nor a center of rotation that becomes the Cres of the tooth. During clear aligners ‘ treatment, the tooth’s Cres- location is always at the root. At the same time, in fixed appliances, the Cres is a fully controllable point by the orthodontist, depending on where the bracket is bonded on the crown and the stiffness of the wire.
Hello sir ,
I do agree that reducing plastic waste is the duty of each one of us. Yet another concern which keeps boggling my mind is release of microplastic from the use aligner . Which might on a long duration say use of a comprehensive three years or five year package offered by Invisalign might be carcinogenic . It’s high time we curtail the unwarranted use of Aligners over a long period of time .
With appreciation, this is very useful information. Align, Technology states they have data for “over 17 million patients”. Hopefully, in the near future they will encourage unbiased research into their remarkable data base.