Do functional appliances influence skeletal pattern? More reviews giving us the answer!

Do functional appliances influence skeletal pattern? More reviews giving us the answer!

I have just returned from the excellent AAO meeting in Orlando, where I met many followers of my blog. It was great to receive their feedback and I am genuinely surprised at how many people follow my postings. In this week’s post I’m going to review two systematic reviews on functional appliances. These were in the recent addition of the AJO-DDO. Both aim to identify skeletal effects of functional appliances.

Fixed functional appliances with multibracket appliances have no skeletal effect on the mandible: A systematic review and meta-analysis

Ishaq et al

AJO-DDO Volume 149, Issue 5, Pages 612–624

These investigators carried out a systematic review to evaluate the effect of fixed functional appliances combined with multi bracket appliances on class II skeletal pattern.

What did they do?

They carried out a systematic review of articles published until April 2014. They included papers reporting randomised clinical trials and non-randomised controlled clinical trials. Each study had to include an untreated control group. Their main outcome measure was cephalometric data collected at the end of the functional phase of treatment.

They assessed risk of bias  with the Cochrane tool for  RCTs. They used the Newcastle-Ottawa scale to assess the quality of the non-randomised studies.

They initially identified 1366 papers and after the usual filters they identified 5 trials. These were divided into 1 RCT, 2 quasi RCTs and 4 prospective controlled trials.  There was some variation in the measurements used in the studies, nevertheless, they did extract data on relevant measurements. This data was not presented in the table and I found it a little difficult to follow.

In summary, they showed that the use of fixed fractional appliances when combined with multi-bracketed appliances did not have an effect on the skeletal pattern. However, the evidence was weak.

Ceph_(2)Effectiveness of orthodontic treatment with functional appliances on maxillary growth in the short term: A systematic review and meta-analysis

Nucera et al


 AJO-DDO  149, Issue 5, Pages 600–611.e3

This was a paper from a team based in Italy and Greece.

What did they do?

They carried out this systematic review to find out if there was an effect of removable functional appliances on maxillary growth.

They included studies that were randomised controlled trials and prospective controlled clinical trials that included an untreated control group. Again, the outcome measure was cephalometric measurements.

They carried out the usual search, filtering and assessment of risk of bias. They finally identified 14 papers. These were divided into 4 RCTs and 10 prospective CCTs.

What did they find?

They found that the main effect of functional appliances on the maxillary restraint was -0.61° per year. This was statistically significant.  But my feeling is that this was not clinically significant

They also found that there was a mean difference of -0.61 mm in anterior maxillary displacement. There was no effect on maxillary rotation.

In the discussion they pointed out that they only found a small number of trials and this led to a large amount of variation in the data. Nevertheless they did conclude that removable functional appliances appeared to inhibit sagittal maxillary growth.

What did I think?

A few weeks ago I covered another systematic review on the effects of functional appliances on skeletal growth. You may remember that this was on the effects of fixed function appliances and the authors concluded that there was no influence on the skeletal pattern to a meaningful degree. It is interesting to see that these two papers have reached the same conclusion.

In the comments section of my previous post Carlos Flores-Mir pointed out that in the last 10 years there have been 25 systematic reviews on class II treatment. He also felt that the most important findings from any trial should be concerned with factors such as compliance and patient experience. I totally agree with him.

The authors of both of these papers made the “usual” conclusion to a systematic review that “more RCTs were needed”. I am not sure that I agree with this statement as it is now becoming very clear that functional appliance treatment does not influence cephalometric measures to a clinically important degree.  Nevertheless, I think that if further trials are to be carried out investigators should evaluate other outcomes such as compliance, experience, socio-psychological factors, trauma and even breathing.  These are far more important outcomes that are relevant to our patients.

I cannot help feeling that we are in danger of carrying out too many systematic reviews into Class II malocclusion based on cephalometric measurements. There appears to be a trend to review the effects of every individual functional appliance on every different facial bone! I am worried that we will soon be having systematic reviews of systematic reviews in the endless quest to find out if we can alter facial growth.

At this point I’m sure that the question has been answered. I will also not write another blog on a systematic review on the effects of functional appliances.

Finally, I will make a plea to investigators and Journal editors. Please make this stop….. and I do not think that CBCT will tell us any more than we know now!

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  1. Another excellent topic. Considering this and in light of the significant evidence now available on Class II treatment, do you feel the term ‘functional’ appliance is really a misnomer, hanging on from when we hoped they influenced a patient’s functional environment and grew mandibles to a significant degree? Perhaps to move on as a profession and to be honest with our patients, we should be using the less ‘holistic’ term of a ‘Class II Corrector’ which more correctly describes their clinical effect.

    • Hi Peter, yes I agree, but I suppose that we can still call it a functional appliance because it uses the forces of function to tip the teeth? But I like the term Class II corrector..

  2. I agree with Kevin about the redundancy of continuing studies about functionals. They may have
    statistical significance but minimal skeletal significance. Let’s move on. You can’t improve on a
    paper clip or a safety pin, so quit trying to fix something that isn’t broken.

  3. I thought this was laid to rest by Lysle Johnston in his numerous papers in the 1990’s (e.g. Growth and the Class II patient: Rendering unto Caesar; Seminars in Orthodontics, March 1998 Volume 4, Issue 1, p1-62)

  4. “systematic reviews of systematic reviews” well said, we can expect this in future. The request to the editors is genuine. Science of orthodontics will not develop further with redundant publications.

  5. These studies are very interesting and we all agree that skeletal body changes are probably so small as to be almost insignificant . What is clinically more significant is facial profile changes , and correct mandibular posture , and the improved dental physiology that is experience when the mandible is free and not entrapped or distalised . This is a mute clinical point that is still missed by many when treatment planning and upper premolars are incorrectly removed with very negative physiological effects on the patient later in adulthood . If the tmj clicks the mandible is probably distalised already . Upper arch extractions remove the last chance this unfortunate patient had of allowing the mandible to posture forward into and better tmj and mandibular position , that would have been achieved with a non extraction approach . I think this needs to be emphasised as much as the difficult functional case that will not posture forward , that we have all disappointingly experienced .

    • Yes, this is a very controversial topic, and sensitive. I trained with Dr. Ronald Roth who at the time stressed the importance, in his view, of of a “seated condylar position” , which, of course does not mean over distalized or locked back with a deep bite. He was opposed to functional appliances because they brought the condyles down the eminence into a “non-reproducible” position. In light of what we are learning with possible airway issues associated with extractions in some cases, as we may see in our new technology with CBCT, it is obvious we need more research and discussion. My opinion is that what is good for the goose is not necessarily good for the gander, and that each case and treatment plan needs to be individualized and it is risky to make broad generalizations. A patient with a large overjet, proclined incisors, full upper lip, healthy TMJ and good airway may be okay with upper bicuspid extractions whereas for other patient situations this may be totally inappropriate.

    • Oh my goodness! Who are you to say the mandible is “trapped” and needs your erudite help to release it? Dr Galahad?

  6. Hey Kevin,

    Was a pleasure meeting you in Orlando. I’m a avid reader of your blog.

    You should look into Smile-Radar. I came across this App in Orlando. Its a great tool to monitor patient compliance with removable appliances without having my patients to actually come into the clinic. Furthermore, I discovered yesterday that the App saves all the photos sent in by patients on the cloud. This helps my staff to use their time more efficiently.

  7. Excellent topic! I’m a student and I found difficult to compare what I hear in congress or read in book with these sistematic review. What do you think about new three dimensional technology for the acquisition of patient soft tissue? They can be superimposent and compared.

    • I am not sure that CBCT will tell us much more than we already know. I would worry about studies looking at this as an outcome as this will increase the radiation exposure to the people in the trial, with potentially very little benefit in terms of research findings

  8. Now that we know that functionals do not grow jaws what do we do with the info? Do we stop using them? Do we wait for jaw growth before treating? It would be interesting to know how orthodontists around the world have responded to this discovery, or has it made no difference?
    I basically see treatment during the growth spurt as utilising normal mandibular growth to jump the bite and maybe avoid upper extractions so use an upper removable bite plane with a mid screw together with a lower fixed and class 2 elastics. Seems to work as well as any other so called functional. Am I right in thinking this way?
    I did ask the editor of the AJODO a few years ago why they carried on with the orthopedic part of the journal title when there is no such thing and he agreed and said it had been debated but too many people still believed and were reluctant to change the title. I suppose we sound more important if we think we are dentofacial orthopedists rather than tooth rearrangers.

    • Hi Andy, I let my patients know that a functional appliance will fix their prominent teeth and this works very well, if they wear it. They do not ask me if the appliance will make their mandible grow. I think that it is orthodontists and dentists who tell them about growth modification or orthopaedics. Perhaps, we should stop telling them this?

      • Hi Dr. Kevin,

        Probably this mistake is made by many…including me to convince the parents n to reinforce the wearing of functional aapliance …. Probably from next time will refrain from using the term jaw growth modulation and concentrate more of patient concern of prominent teeth and their correction…..
        I just have one doubt… Let’s say a 11 yr boy with peak growth spurt retrognatic mandible…chief complaint ..prominent upper tooth…Angles full cusp class 2 overjet 10mm and positive vto ….now what 3 option (functional; fixed functional; start aftr puberty and extraction)would you suggest to parents in order of your preference and why.

        P.s. I will mail you one such case which I treated with twin block….got decent results ….it was difficult for the parents to convinc for twin block initially ….total treatment time was 28months…. Would like to know your view on this .

  9. Hi sir i am agree with you but if absolute anchorage like TADS use at the center of resistanc this will effect more on skeletal growth restrain.

  10. It’s brave of Kevin O’Brien to stand up as an orthodontist and to read the proper science to us, & help discredit this myth of splint therapy.
    But say it clear & out loud Kevin… “functional appliances pull back big front teeth… they don’t grow small lower jaws”…
    why is the argument important? Because if you don’t treat the real problem, you practice pretend medicine. That small lower jaw & thin airway in a kid, becomes OSA when they are 50.
    Only significant surgery can make it bigger.
    But then, Orthodontists are not surgeons.
    I toast the truth mongers…??

  11. Can you help me to find and know recent trend in growth modifications.
    Do you think that one phase Ortho. ttt is best or two phases ttt.

    • Hi Mohammad, thanks for the question. Most of the trials that have been carried out in this area, have suggested that one phase treatment in adolescents is the most effective method of treatment.