August 31, 2020

Let’s have a first look at Midfacial Skeletal Expansion (MSE).

Orthodontics may be in an expansionist phase. Recently, there has been a large amount of social media publicity about Midfacial Skeletal Expansion (MSE). I thought that this paper provided us with some initial evidence about this technique.

Orthodontic expansion is clearly an established form of treatment. There are several methods of expansion. However, Rapid Palatal Expansion is indicated when there is a marked skeletal transverse discrepancy.    When RPE is provided before the palatal suture is fused, there is expansion at the suture. Nevertheless, there are also risks of tooth tipping, bone dehiscences and root resorption. This is because the RPE appliances are tooth-borne.  Concern over these side effects has led to the development of bone borne expanders. One of these is the Midface Skeletal Expander.

The inventor of this technique was a co-author of this paper. He also holds the patent for the Midfacial Skeletal Expansion device jointly with Biomaterials Korea.  In the introduction, they stated that this technique had been thoroughly studied.  They quoted three papers to support this claim.  I had a quick look at these. One article was a case report, the other two papers reported on cohorts of 15 patients.  I am not sure that this is “thoroughly studied”. I shall look at this evidence in another blog in the next couple of weeks.

The authors pointed out that when we measure the effects of MSE, we should use an angular measurement system to take into account that expansion is archial.

I decided to have a good look at this paper because it dealt with a new, perhaps controversial, method of treatment.

A team from Los Angeles did this study. Progress in Orthodontics published the paper.

What did they ask?

They did this study to :

“Quantify the differential components of MSE expansion by calculating the fulcrum locations and applying a novel angular measurement system”.

What did they do?

They did a retrospective study and analysed the records of 39 successfully treated patients.   All had been diagnosed with maxillary deficiency and were aged 18.2 years.  Importantly, the patients had to have CBCT images taken at the start of treatment and within 3 weeks after active expansion.

They identified the maxillary deficiency using lines drawn at coronal cuts of the CBCT images. You can find details of this in the paper.

They developed a rather complicated method of measurement. Essentially, they superimposed the sequential CBCTs on the cranial base. They then identified the fulcrum of any skeletal movement. I thought that this methodology was very complicated, and to be honest, I could not understand it. Perhaps, I am getting old, but this was beyond me.  They then used the traditional linear measurements and the novel angular measurement to evaluate the effects of the treatment. Finally, they ran univariate statistical tests across several pre and post-treatment variables.

What did they find?

They provided a large amount of data and statistical tests. I extracted the most relevant variables into these tables. The first is the traditional linear measurements.

Treatment change (mm) Means and 95% Cis
Zygomatic line 2.31 [1.986, 2.614].
Alveolar bone line 2.93 [2.5659, 3.2941]
Dental Line 3.84  [3.3253, 4.3547].

They suggested that this represented 60% skeletal expansion, 16% alveolar bone bending and 23% dental tipping.

This second table is the angular measurements.

Treatment change (degrees) Means and 95% Cis
Frontozygomatic angle 2.82 [2.423, 3.177]
Fronto alveolar angle 2.83 [2.4534, 3.2066]
Frontodental angle 3.92 [2.5434, 3.2966]

These values represent 96% skeletal, 0.3% alveolar bone bending and 0.09% dental tipping.


They concluded:

“MSE produced almost pure skeletal rotational movement. Importantly, alveolar bone bending and dental tipping were not statistically significant”.


“Conventional linear measurements can falsely exaggerate the alveolar and dental components of MSE treatment”.

No authors declared a conflict of interest.

What did I think?

Firstly, this is a retrospective paper, and I do not usually review these unless it raises important issues about a new technique. I felt that this was the case with this paper.  We need to remember that when a study includes retrospective data, we must assume that it is subject to selection bias. Unfortunately, this is the case with this paper because all the patients were successfully treated. As a result, we do not know anything about the cases that were not successful. No one is 100% successful in all their treatment.

Nevertheless, we should not totally ignore retrospective papers. This is because they provide useful information that can be used for sample size calculation for future trials. Significantly, we should not change our practice based upon retrospective studies.

I would like to see a trial of this technique. The authors state that this is not ethical. I disagree.  They could randomise to MSE and a delayed treatment group.  This would not be unethical because the control group can be treated six months later. As they are not growing, there would be no harmful effects.  This would be a great study.

Unfortunately, I was not too convinced about their method of measurement. I could not help thinking that a new measurement was developed to evaluate a new technique?

Final thoughts

It was important to see that the effect sizes were relatively small. For example, they were in the order of 2mm with wide 95% confidence intervals. I am not sure that these are clinically significant and I would like to see what we can get with traditional RME.  I am posting about a trial that looks at this later this month.

Finally, in writing this blog, I came across a large amount of information about this invasive technique. Consequently, I am going to have a closer look at this and post about it. Hopefully, this will help us understand this novel and exciting approach a lot more.



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Have your say!

  1. Nice

  2. just wondering what a diagnosis of maxillary deficiency actually means. It certainly sounds serious, but does it just mean a cross bite? I wonder how many patients actually complain about this or just worry about it after the diagnosis.

  3. Dr. OBrien,
    Thank you for your blog postings. There are many MSE providers that have lots of Data about it. Dr. Evans has a huge pool of patients. Dr. Ting has about 400 cases. They should be a good resource for research. I have provided some cases too. One critical point I have about your comments is that The MSE technique Is NOT INVASIVE as you said it is. In my opinion extractions are a lot more invasive!
    Thanks again

    • Where the heck are the clinical trials that justify the use of this technique by Evans and Ting?

      • There is no need to justify every technique by clinical trials, my dear TommyR.

        There is something called experience, and also a very interesting thing called common sense.

        • Yes, and we had bloodletting from the Egyptians throught the late 19th centurey based on such “common sense” to rid one of bad humours.

          • The equivalent of bloodletting would be extractions and retracting the patient’s jaw right into their throat, not expanding the maxilla and giving someone increased oral and nasal volume. There is a reason why many people, including me, have gone out of their way to seek MSE providers, instead of orthodontists and their so-called “proven methods”. I also doubt Edward Angle used clinical trials to devise his treatment plans , otherwise he would have realised how dangerous the use of some of his appliances such as headgear is. There is a reason why the stanford sleep medicine center uses DOME and MSE to treat sleep apnea, it’s because it works and Dr Moon has compiled significant data showing increase in both oral and nasal volume provided by MSE.

  4. Thank you for looking closely into palatal expansion; this is the issue that brought me to your blog as I’m concerned about the fervor with which palatal expansion is pursued in my part of the world. The resulting effects on facial structure often look unnatural to me. But of most concern is the degree to which some form of this invasive procedure is insisted upon in so many cases, when the ‘science’ behind it is sparse and the explanation I hear over and over again is because “humans eat more processed food now, so their jaw has shrunk over time and can no longer support the size of their teeth.” This sounds like the starting point of pure quackery.

    • Danielle, MSE (or other MARPEs) are not used because of the food the patients might have eaten during their growth. They are used because they work, they are more comfortable, more hygienic (more than the HYgienic RApid eXpander) and have an almost pure skeletal effect.

      I agree (or I think I agree) with you that the diet theory is overemphasised in detriment of a quite understandable an plausible genetic component, although experience shows that strong myofunctional components affects growth, so probably diet does as well. Nevertheless, in my opinion genetics still plays the major role.

      • Genetics would involve millennia whereas these changes have occurred within 250 years (pre industrial revolution). Hate to use the phrase but epigenetics would be more appropo.
        If we consider the tongue should be the driving force for maxillary growth both transverse and sagittal, not only does the aetiology become clear but so does the recognition of the pervasiveness of this issue exacerbated iatrogenically by extraction orthodontic therapy.
        Research takes time and so I echo the above sentiment that common sense dictates we must help those whom the Hippocratic oath has failed.

  5. Can’t quite get my head around this archial movement. Where is the center of rotation? All points cephalad to the center of rotation would tend to rotate medially as the maxilla rotates laterally. Where does the orbital process of palatine bone, that little presentation on the medial wall of the orbit, archially move?

    Although true of RME as well as this MSE, any tooth borne expansion retention, whether arch wire and conventional appliances or retainer, the skeletal relapse (equal and opposite archial movement) COULD permit the same long term resultant positions of simple archwire expansion . Besides a randomized sample with a 6 month delay, hoping there’s a 3-5yr follow up for MSE, RPE, ArchWire.

  6. What is very surprising to me is that when I crawled around the internet looking for academic findings on this topic; I found TOTALLY unqualified folks ,especially on u tube,giving “opinions”on all these “expansion “techniques “including “mewing”.
    What is more worrying is the number of questions that are posted relating to u tubes produced by a socially distanced individual sat in a basement ,,
    Seems we have entered the era of Gwyneth Paltrow Orthodontics!!
    Thank God for your blog Dr O,brien!

  7. From 1998 to 2017 or so, my favorite approach to correct maxillary transverse deficiency was Surgically Assisted Rapid Palatal Expansion for non growing patient (older than 18y). In 2003, with the help of Dr Proffit, I did a prospective research to find out if the stability of SARPE was better than the expansion with multisegmented Le Fort 1 (JOMS 2008, AJODO 2011). We found out that dental expansion with SARPE was not more stable, but skeletal expansion was very stable.
    I am using MSE device since mid 2017. I had some difficulty with 2 patients and 2 other , it simply failed to split the maxilla. We kept the same device but ask for a corticotomy “à la SARPE”.
    The advantage of this device with miniscrew combine with the osteotomy cut is the parallelism of expansion of the hemimaxilla in frontal view and bigger basal expansion.
    The other advantage is that most patient between that have the indication of maxillary expansion can have it without surgery. Hence this technique is, in my opinion, less invasive than SARPE .
    Having said that, one should keep in mind that patient older than 30-35 may still require corticotomy because the MSE failed to split the maxilla.
    But most younger patient can avoid the SARPE surgery and benefit from less invasive 4 screw approach.

    • Mate, you are doing a actual SARPE!

      A minimally invasive one but a SARPE. surgically assisted ROE.

      Corticotomies are surgery!

      Many dentists and patients are confused about the success ratea some orthodontists claim to have and it is the reason! It is just that you put all patients in the same box.

      So biased figures!

      • Dr Sergio, how can I contact you with questions about MSE? I’ve read you are a provider and wanted to ask your thoughts after using it yourself!

    • Would you confirm that when you say corticotomies you are referring to a SARPE along the lines of Proffitt (and his references to your co-authored papers), a SARPE that is in essence a LeForte I without the downfracture?

      Note: Even with this SARPE the movements of the hemimaxilla are not parallel but have a center of rotation somewhere in the “upper nose”


  8. I would love to know what the soft tissue changes at the zygomatic ridges are? Akin to jaw surgeries, not every millimeter of advancement in bone gets expressed in the soft tissue. How about the MSE? How does the soft tissue width compare to the hard tissue? Is it one to one?

  9. Dear Prof O’Brien

    Thank you for posting this paper.

    Will you please elaborate upon what you describe as ‘…. marked skeletal transverse discrepancy’ when discussing indications for RPE in this trial/per se?

    Also sir, would you maybe offer an opinion as to precisely when in their childhoods each of these 18.2 year-olds comprising the experimental cohort were first diagnosable (and possibly first treatable?) for ‘marked transverse deficiency’?

    Thank you for considering my inquiries.

    Kevin Boyd
    Pediatric Dentist

    • Thanks for the questions. I could not find this information in the paper. But I suggest that you read it and see what you think about their definitions etc?

      • Thanks Prof.

        Let me rephrase; will you please offer me your own personal opinion as to when these adolescent patients described in this study with pre-Tx diagnosis of ‘marked transverse deficiency’ of the maxilla(MTD), were first diagnosable for MTD. I think you might enjoy reading Jim McNamara’s (et al) ‘The role of RME in the promotion of oral and general health’(Progress in Orthondontics (2015)16:33) where the author’s conclude that in growing kids (mixed dentition)‘….RME is able to reduce the symptoms of OSA and improve PSG(sleep study) variables.

        • Thanks for the comment. In answer to your first question. I do not know because this was included in the paper. I have had a look at the paper by McNamara in Progress in Orthodontics. This was a very basic review of the literature that did not take the quality of the included papers into account. It is important to point out that this was not a systematic review and is, therefore, of little value.

  10. There does not seem to be much discussion about the very real risk of fractures at the nasal bones and orbits – particularly in mature individuals. This seems odd to me given that palatal expansion has been around for such a long time and surgical procedures were developed to aid in making expansion more predictable in adults.

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