RESULTS OF A RCT OF A PREFABRICATED FUNCTIONAL APPLIANCE - MYOBRACE

One of the most popular topics in my series of Blogs has been on prefabricated #Myofunctional appliances and so I thought I would share the results of this randomized clinical trial from Sweden which was presented at the recent 8th International Orthodontic Congress in London. The complete abstract is below and follows on from their paper reported at the 7th IOC in Sydney in 2010 which I reported here.

The conclusions reinforce that the overjet/protrusion correction obtained with the prefabricated Myobrace was dental/tipping of teeth while the custom made #Activator appliance achieved a better molar correction, however compliance with both appliances was poor. This will affect the clinical choice of an appliance as in cases where simple tipping may be suitable then the cheaper prefabricated appliance may be appropriate. However if more molar bite correction is required then the custom-made appliance would be more suited.... as long as they wear it. The percentage of subjects in this study having unsuccessful treatment was very high at 70% with the Myobrace appliance and ~53% with the Activator which the authors attributed mainly to a lack of compliance. The patient and the family should therefore be involved in the appliance choice or alternatively appliances that do not require as much cooperation can be used (the subject of a future Blog). These authors are to be congratulated on a job well done in conducting this trial.

Update: The full paper is now available in the European Journal of Orthodontics.

Authors

E. Cirgic, K. Hansen, H. Kjellberg.

Abstract:

TREATMENT EFFICACY OF PREFABRICATED FUNCTIONAL APPLIANCES AND ANDRESEN ACTIVATORS IN CLASS II, DIVISION1 CASES: A RANDOMIZED CLINICAL TRIAL

Aim: The purpose of this study was to compare the clinical effectiveness in reducing large overjet between a prefabricated functional appliance (PFA) and a slightly modified Andresen activator (AA). Methods: A multicentre, prospective and randomized clinical trial was conducted in 12 general dental practices and an ethical committee approved the study. The sample consisted of 97 subjects (44 girls, 53 boys) mean age 10.3 years with a Class II, division 1 malocclusion and an overjet ≥ 6 mm. The study was designed as intention to treat and the patients were randomly selected to treatment with either a PFA or a AA. The PFA and AA group consisted of 57 subjects (28 girls, 29 boys) and 40 subjects (16 girls, 24 boys) respectively. Overjet, overbite, lip seal and sagittal relation were recorded before and at 3, 6 and 12 months after start of treatment. The endpoint of treatment was set to overjet ≤ 3mm and after this a 6 months retention period followed. Results: No significant difference was found in overjet, overbite and lip seal between the two groups. Significant difference was found in sagittal molar correction between the two groups. The treatment of 40 patients with PFA and 21 with AA were considered unsuccessful mainly due to poor compliance. Conclusions: Prefabricated functional appliances are as effective as Andresen activators in correcting overjet, overbite and lip seal. Andresen activators seem to be more effective in sagittal molar correction than PFA. The success rate in treatment with both appliances is however, low.

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'.

MORE ON MYOFUNCTIONALS - 2 CLINICAL TRIALS

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.

WHAT AGE IS BEST FOR ORTHODONTIC TREATMENT TO ACHIEVE THE BEST JAW GROWTH?

Many orthodontic associations around the world recommend an orthodontic exam at age 7 but does this mean your child needs treatment then? There is much debate over what is the best time to treat protrusive upper teeth and/or a retrusive lower jaw (Class II bite like Bart). Some suggest waiting until adolescence (when all adult teeth have erupted), others earlier at age 9-10 with functional appliances such as Twin Blocks, Activators or Bionators, while others suggest even as early as age 5-6 with myofunctional appliances (covered in a previous Blog)!


The evidence supporting very early treatment with myofunctional appliances at age 5-10 is of low quality and that research demonstrates only small clinical changes of ~2mm which for most is not a significant change. Much higher level evidence from well-designed randomised clinical trials have demonstrated that you can treat much worse bites with protrusions of 7mm and more at ages 9-10 but also just as effectively during adolescence when all the adult teeth have erupted (~ages 13-14). The only advantages of treating earlier are in the form of improved self-esteem earlier than if treated later, and a modest reduction in trauma discussed in a previous Blog. Self-esteem can be an important issue for some and a valid reason to consider early treatment.

Some have suggested that you can predict the timing of treatment based upon x-ray markers of growth such as hand-wrist x-rays or more recently using cephalometric radiographs of the skull and identifying the developmental stages of the cervical spine (neck bones), called the CVM method. The CVM method was based upon work by Dr Don Lamparksi from the University of Pittsburgh where I trained and was later revised by others. The timing of peak growth varies widely from 8½-11½ in girls and 10-14 in boys. Research has demonstrated a low agreement in identifying the stages of  these spine markers and that it cannot predict the onset of peak mandibular growth. You would also likely need multiple radiographs to determine when you are actually approaching peak growth and by the time you see it you are already at the peak or past it. But let’s say you do achieve the perfect timing for treatment with an appliance such as a Herbst. In this study evaluating patients treated with a Herbst appliance the authors found that with ideal timing compared with a historical control they found 1.9mm advancement of the chin (Pogonion). Firstly a historical control from over 50 years ago does not allow a valid comparison as the amount and timing of peak growth has changed over the past 50 years. We will also overlook the stability issue in that functional appliance studies always show some early growth effect but that long term the growth slows so there is no difference between those children treated earlier and those treated in adolescence. So now let's compare it to a study using a Herbst in ‘non’-growing adults. They still found a 1.3mm advancement of the chin (Pogonion) so with ideal timing vs. non-growers there is only a 0.6mm advantage! You then have to ask yourself 'Does 0.6mm matter' and most would accept that this is not a clinically meaningful change. Now back to the issue of timing and efficiency - if the treatment time is a little shorter (as growth helps you out a bit more) at the ideal time, then you possibly (and this is unclear) save 2-3 months in overall treatment time compared to treating much earlier or much later This then comes down to whether you consider this potential time saving a big enough benefit to try to determine this most ideal time. However I would not consider it a critical issue.


So why age 7 for a screening exam? Most do not need treatment at this age but it is a good age to identify the small number that would benefit form an early intervention such as early loss of baby teeth that result in space loss, or crossbites of front teeth. Others could be left until age 9-10 e.g. to preserve space to reduce crowding or identify those developing impacting maxillary canine teeth (much easier to intervene at age 9-10 then try to treat a fully impacted canine at age 14-15), while the majority can quite happily wait until all adult teeth have erupted in early adolescence. However your orthodontist does not want to miss the small number that could greatly benefit from such early interventions so if you are unsure then seek a consultation with your orthodontist who can then inform you of the most appropriate treatment time as well as the pros and cons of any options.

Dr Peter Miles is the orthodontist at Newwave Orthodontics in Caloundra, Australia, editor and author of the textbook Evidence-Based Clinical Orthodontics, and teaches orthodontics part-time at the University of Queensland and is a visiting lecturer at Seton Hill University in the USA.

MYOFUNCTIONAL APPLIANCES - WHAT'S THE EVIDENCE?

Myofunctional therapy is treatment aimed at changing muscle (Myo = muscle) function and possibly influencing jaw growth and the position of the teeth. Myofunctional appliances have been around in various forms for many years. These can include lip shields and screens, eruption guidance appliances and the T4K™.  Although claims are made that they alter muscle function resulting in improved facial growth, better alignment, and more stable results, what evidence is there to support these claims?

There are a number of studies examining the clinical effects of the eruption guidance appliance and the T4K™ and they provide clinical evidence as to the compliance and effect of these appliances.1-5 These appliances are available in a small range of sizes where one is selected to suit an individual rather than being custom made from an impression/scan. Possibly due to this generic fit, one study found 31% of patients did not wear the appliance.1 A randomised trial of the T4K™ vs. a custom made Activator appliance found the Activator caused less discomfort than the T4K™ and was more acceptable.6 All five studies showed that treatment at age 5-9 was quite long (13-36 months) and protrusion of the top teeth was reduced by only a small amount (1.5-2.5mm).1-5 A study of the T4K™ appliance showed it had no growth effect.3 Another study on the eruption guidance appliance followed patients over time and found the small 2mm improvement in crowding relapsed to the initial state which shows it is not stable.4 A 2mm improvement in bite depth was also unstable and relapsed leaving only 0.5mm of change.

A 2mm change is considered a minor improvement and could be treated once all adult teeth have erupted (~age 12-13) in one phase of treatment. This results in a reduced overall treatment time as well as potentially less cost than doing two or more phases of treatment. Clinical trials in the both the USA and the United Kingdom where patients were randomly assigned to early or late treatment have shown that when patients were treated early for much more severe protrusions (7mm rather than 2mm) they could be treated equally as well by delaying treatment until all the baby teeth had been lost.7,8 The result of treating later (~ age 12-13 years of age) was a shorter overall treatment and less cost. However a case can be made for early treatment to reduce protrusive teeth when the appearance or function is concerning the patient or for a small reduction in the risk of trauma to the front teeth (see my previous post on trauma).

So if you are unsure about whether early treatment is required for your child, consult your orthodontist. Some problems such as crossbites and impacted teeth can be detected and treated more effectively if found early. Your orthodontist is an expert in growth and development and can best determine if early treatment or simply monitoring your child is indicated to achieve the most efficient and cost-effective treatment at the most appropriate time.

References:
1. Keski-Nisula. American Journal of Orthodontics & Dentofacial Orthopedics 2008;133:254-60
2. Methenitou. Journal of Pedodontics 1990;14:219-30
3. Usumez. Angle Orthodontist 2004;74:605-60
4. Janson. American Journal of Orthodontics & Dentofacial Orthopedics 2007;131:717-28
5. Myrland et al. European Journal of Orthodontics 2015;37:128-134
6. Idris. European Journal of Paediatric Dentistry 2012;13:219-24
7. Tulloch. American Journal of Orthodontics & Dentofacial Orthopedics 2004;125:657-67
8. O’Brien. American Journal of Orthodontics & Dentofacial Orthopedics 2009;135:573-9

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.

WHAT TO DO ABOUT THUMB SUCKING AND TONGUE THRUST?

Open bites or front teeth not overlapping can be caused by habits with fingers, lips or the tongue placed between the teeth but how should we treat them? Habits can often be corrected early with minimal intervention. We prefer to see the habit reducing as the adult incisors erupt, about age 6, but even those at ages 9-10 stopping the habit results in improvement of the #openbite. Many children stop themselves by age 6 as they interact with their peers and decide it is not as socially acceptable.

Those that persist beyond age 6 we suggest initially trying reminder and reward strategies as in this case on the right. Remind the child in a non-threatening manner and set a goal e.g. praise them when they have refrained and perhaps have a small reward if they have stopped for a week (to involve the child in treatment). Reminders can be physical such as a sock, mitten or hand puppet at night. An elastic elbow support over the elbow to make it harder to bend the elbow to suck the thumb could be considered. Thumb ‘paints’ work for some but others will simply suck it off. If these attempts do not work, then a more intrusive reminder such as a thumb crib/habit appliance can be fixed in place by an orthodontist. Some persist due to emotional issues and the habit is a comforting device so when the child is upset, they are more likely to suck and it is more difficult to correct as the underlying cause is still present. Scolding them will simply make this worse.

A long held concept is that a tongue thrust swallow is the cause of open bites but it is actually an adaptation to an open bite (to swallow you need a seal at the front and so the tongue is placed between the teeth). We swallow about 600-1000 times per day for 1 second each (~10-17 minutes per day) which is not enough time to cause the open bite, it takes hours to move teeth not minutes. However, ‘habits’ such as thumb sucking or forward resting posture of the tongue between the teeth can be of sufficient duration to cause an open bite. Some may need help with exercises to retrain the tongue to position itself correctly and a Speech Pathologist can help with this. If these strategies are not working, then consult your orthodontist to consider placing a thumb or tongue crib as a final resort.

DOES EARLY TREATMENT OF PROTRUSIVE TEETH PREVENT TRAUMA?

 

Protrusive or bucked top teeth are at a higher risk of trauma but how much is this risk and should you seek early #orthodontic treatment to reduce the risk? Kids run around and can't be protected from all harm so it is no surprise that some trauma will occur. A recent systematic review, one of the highest levels of scientific evidence, found that the risk of trauma in children having orthodontic treatment at the ages of 9 - 10 was 19.8% while those receiving later treatment in adolescence (say ~13) it was 29.2% so there is a 9.4% additional risk of trauma if delaying treatment.

This sounds ominous to some but most are not at additional risk. The studies this review were based upon also concluded that early treatment led to more overall time and cost than later treatment. Some would therefore choose to delay treatment but some of the more active/sporty patients or those not willing to bear the risk will seek early treatment. However what type of trauma are we talking about? This is discussed in the textbook I helped edit and author titled, Evidence-Based Clinical Orthodontics.

One of the clinical trials included in the review quantified the types of trauma seen in those receiving early or late treatment and they found that 80% of the trauma was in the enamel only (small chips as pictured) while 19% were more involved and into dentine while only 1% had reached the nerve. If we then consider major trauma to be only the dentine and nerve involvements (or any knocked out) this is only ~20% of all the additional trauma. This then gives 20% of 9.4% (or 0.2 x 9.4%) which is only a 1.9% higher risk of a major trauma if delaying treatment until the age of ~13 rather than treating at age 9-10. This then allows you to make a more informed choice about the risk of trauma if choosing to delay treatment of protrusive upper teeth until all the adult teeth have erupted.

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.