Monday, 20 April 2015


Some manufacturers of myofunctional appliances claim that that they achieve better results by treating at a very young age (~5-8 years of age) but what is the evidence? I have Blogged on this topic previously but more recently I came across two unpublished randomised clinical trials (RCT's - which are considered the more robust way of testing a treatment) where they compared myofunctional appliances with conventional functional appliances - so what did they find?

The first was presented at the European Orthodontic Congress in Istanbul- Turkey (Abstract book, scientific poster :361) and was a follow-on from their previous study evaluating comfort of myofunctional appliances where they found the Activator caused less discomfort and was more acceptable than the T4K™ myofunctional appliance  (Eur J Paediatr Dent. 2012;13:219-24). The follow up study evaluated the effectiveness of the appliances and the abstract (found here) presented the results of the 60 patients treated over the 14 months of the study. The authors found that the Activator group showed better skeletal improvement than the myofunctional T4K® group. They also found that the facial convexity improved significantly with the Activator and to a lesser extent with the T4K® while the soft tissue profile was improved only by the Activator. They concluded that the Activator is more effective than the T4K® in treating patients with protrusive upper teeth (Class II division 1).

The second paper was presented at the World Federation of Orthodontists meeting in Sydney (abstract #0335 of this PDF file) and was a multi-centre RCT of 74 subjects comparing another myofunctional appliance with an Activator. Although they found that the prefabricated myofunctional appliances were as effective as Activators in correcting overjet/protrusion, they were less effective in correction of the Class II molar relationship (bite on the back teeth). This implies that the main factor in correction of the overjet/protrusion was only due to tipping of the front teeth as discussed in the previous Blog on myofunctionals (study by Usumez. Angle Orthod 2004;74:605-60). However the advantage with the myofunctional appliance is that no impressions are needed and the cost is less than that of the Activator.

So it would seem that myofunctional appliances have 'some' effect but were less effective than the custom made Activator appliance, particularly in molar/bite correction and skeletal/growth change. This is consistent with the findings of studies discussed in my previous Blog on Myofunctional appliances.

If we are then considering what is the most effective appliance then the custom-made appliances win out but a case could be made where in remote communities with limited or no access to laboratories for impressions or making a custom-made appliance, then perhaps a prefabricated myofunctional appliance can offer some improvement. Both of the main authors of these RCT's are currently PhD candidates and therefore extremely busy people but I also believe they are in the process of writing these papers up for publication which will allow a more thorough read of the trial design and findings.

Dr Peter Miles is the orthodontist at Newwave Orthodontics in Caloundra, Australia and teaches orthodontics part-time at the University of Queensland and is a visiting lecturer at Seton Hill University in the USA. Peter is one of the editors and authors of the orthodontic textbook, 'Evidence-Based Clinical Orthodontics'. Importantly, he has no financial interest in any products discussed in these Blogs.


  1. Hi Peter. Congratulations.
    Got a question. What is the name of the company that produces those pre fabricated appliances with similar results to the activator appliance?
    Hope those Phds do their homework soon! :D

    1. It doesnt just answered my question; but gave me more valuable information.
      Thank you very much Peter!
      See you at San Francisco!

    2. Hola Sergio, The appliance was unclear in the description so I assume it was the Eruption Guidance Appliance used in the previous studies by Keski-Nisula & Myrland). However if you look at the result it was the 'overjet' that was the same NOT the molar correction. This therefore indicates as with a previous study by Usumez that it is tipping of the teeth that achieved the overjet change which is less favourable than the actual molar correction achieved by the Activator. All studies in this Blog and the previous one on myofunctionals found the myofunctional appliances to be less effective than custom made functional appliances such as the Activator. I hope this has answered your question. Chao!