June 04, 2018

We won’t get fooled again? A new trial on speeding up tooth movement

This post is about a new study looking at micro-osteoperforation. This is an invasive way of trying to make teeth move faster.

Over the past few years several investigators have studied new methods that aim to reduce the duration of orthodontic treatment. One of these is micro-osteoperforation or MOPS. This is a relatively invasive technique and orthodontists make small holes in the gingivae and alveolar bone to cause localised trauma. I have posted about this before and I pointed out that there are no high quality trials that have looked at the rate of individual tooth movement. Therefore, I was very interested to see this new trial.

A team from Jordan did this trial and the AJO-DDO published it.

Three-dimensional assessment of the effect of micro-osteoperforations on the rate of tooth movement during canine retraction in adults with Class II malocclusion: A randomized controlled clinical trial.

Amal Alkebsi et al

AJO-DDO https://doi.org/10.1016/j.ajodo.2017.11.026

I would like to thank the authors for providing these links:

This is a link to the author discussing their paper

The paper can also be accessed here until July 18.


What did they do?

They did a split mouth RCT with a 1:1 allocation of interventions to each side of the mouth.

The PICO was

Participants: Orthodontic patients who were older than 16 years with Class II Div 1 malocclusion requiring extraction of maxillary first premolars.

Intervention: They fitted MBT fixed appliances to level and align. Then they extracted the first premolars and placed miniscrews. When in 0.19×025 ss archwires they did Micro-osteoperforation with miniscrews 1.5 mm wide and 3-4mm deep to a set protocol.  A retraction force was applied from a TAD to the canines. This was done 6 months after they extracted the first premolars.

Control: No MOPS but identical mechanics to the MOPs side of the mouth.

Outcome: The rate of canine tooth retraction per month. They measured this from 3D scans superimposed on the palate.

Importantly, they generated a blocked randomisation, concealment was done in sealed envelopes that were opened by the participants. They collected data blind.

They did a sample size calculation to ensure that the study had sufficient power.

What did they find?

They enrolled 35 patients and three dropped out.

Interestingly, there were no differences in the rate of tooth movement between the MOP and the control sides. This is the relevant data table.

Mean (mm)+/-SD
Mean (mm) +/-SD
pMean difference (mm) (95% CI)
1 month0.67 (0.34)0.65 (0.26)0.770.02 (-0.13,0.18)
2 months1.28 (0.5)1.36 (0.49)0.5-0.08 (-0.33,0.16)
3 months1.88 (0.67)1.93 (0.74)0.76-0.05 (-0.4,0.29)

As a result, they concluded that MOPs did not have an effect on the rate of tooth movement.

What did I think?

I thought that this was a good trial. The authors did this well and reported it concisely. They did not have a commercial interest in the technique.

They used a split mouth technique.  This was relevant to study an intervention with no cross over effects.  I thought that randomisation, concealment and blinding were adequate. Their method of measurement was accurate and has been used in other studies of tooth movement.

Interestingly, they applied the MOP with mini-screws. However, I was not sure how this differs from using the Propel device.  I think that both methods seem to cause the same amount of localised trauma. Perhaps a Propel advocate or Key Opinion Leader could help us here?

My only concern with this paper was that they measured the short term effect of the intervention. I would be more certain about the “absence of evidence” if they had measured tooth movement over a longer period of time.  However, the findings are relevant to the canine retraction phase of treatment.

I’ll take a bow for the new revolution

I feel that this paper adds to our knowledge on the absence of evidence on the effects of MOPs. Perhaps, this is another method of speeding up tooth movement that does not seem to have an effect?

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Have your say!

  1. Kevin I do not see a significant advantage of following this sample for a longer period of time. Let me explain myself. Previous data suggests that the effect of the regional accelerated effect significant diminishes around 3-4 months before a new “injury” is required. That is another claimed drawback of such technique. Patients are not likely to undergo perforations every 4 months.
    The distance form the perforations to the tooth to be moved is important as the potential effect diminishes with distance. The fact that they did the perforations nearer to the canines than the premolars is better. Even then no differences are noted.

  2. Thank you again Kevin

    How much more time will we need to spend refuting the claims of sharks in the profession who provide no evidence when they bite their patients?

  3. Was the TAD placed at the same time as the MOPS were done? You get a RAP effect from that as well. Perhaps they should have done the study without the TADs?

  4. Rate of tooth movement seems a little slow in general. Less than 2mm of movement over 3 months? It seems that rates closer to 1mm/month has been shown in other studies. Not sure if that is correct or means anything. Treatment sequence was interesting. Level and align then extract? In the presence of any crowding, his sequence would tend to move teeth out into cortical bone, which could have slowed tooth movement in general. Just a thought.

    • Intersestingly their intra-oral measurements of tooth movement equal around 1mm/month (from their measurements of canine to 2nd premolar minus anchorrage loss at the 2nd premolar).
      Also their Pearson’s correlation coefficient comparing the two methods of measuring the rate of canine movement (intra-oral measurement and 3D model calculation) is high (r=0.779, P<0.001) but the values themselves seem are quite different. i.e. the intra-oral method of measuring consistently shows about 50% more canine movement on average (and thats factoring in the small amount of anchorrage loss at the second premolar). Seems their 3D measurement method may have high precision and low accuracy?

  5. Forgot to commend you on your Who reference. Nice touch!

  6. Thanks for the WHO paralle! Meet the new boss, same as the old boss.

  7. Dear Mr. O’Brien

    I would like to highlight some points that you forgot to mention in the post above:

    – They didn’t use Propel to do “Propel”. They used a TAD. A TAD don’t have the design and the structure to create the proper injury in the bone.
    – The study confirms what Propel has always said, Its not about the hole it’s about the force.

    It is irresponsible to use in a study a tool that was not created for the purpose. I have been using Propel Excellerator device for 3 years with excellent results, my patients are very happy and my business as well.

    Otherwise, I believe that you are an influential blogger and should be more careful in exposing articles like this, which gives the wrong idea about an innovative technique like Propel.

    Best regards

  8. The study set the teeth up similar to how the retraction was done in the original NYU studies. I do like that. However, I am perplexed if you are going to use Micro-osteoperforations to accelerate a case, at least get you facts and study design down. In this scenario, if you plan to retract the canine, you need to place MOP’s on both sides of the tooth. By not utilizing a parallel design you absolutely create an underlying flaw in the study design. The effect of the MOP exerts an effect across a 3 mm radius. As a result the bone covering the buccal of the tooth on the mesial side is not going to be affected and as such may be a reason why not statistical difference was observed in the trial between the 2 sides. The timing of the placement of the mechanics was approximately 6 months after the teeth were removed. I don’t understand why so long other than to say if they would have removed the teeth immediately before deploying the mechanics the fresh extraction sites would have remodeled faster for them. 2 more items to discuss is due to the fact that the items that they used to create the MOP’s were not designed to due multiple MOP activations, there is some question as to whether or not it makes sense to suggest that this technique was proper for the study at hand. The pitch of the thread, whether the thread is tapered or parallel, the material of the device, whether it is coated or anodized may all have a part to its effectiveness. I just don’t understand why you would not use the actual device from propel if you are going to go through the hassle of creating this study. I have not had a chance to open the full study, but I also am curious if chlorhexidine was used before and after the sites were perforated. Lastly, there was no way to properly measure the depth of the MOP. This too may make a difference as to the response of the retraction of the canine teeth following the placement of MOP’s parallel to the affected teeth. Anecdotally I can only say personally that I have used the Propel device in my practice since 2013. Within my 4 walls, with my own hands activating the device, used properly there is no doubt that this affects the speed at which a full case can treat out. Sure looks like more papers will be required to look further at this topic.

  9. Thank you leaving for sharing! However It would be interesting -and possibly eye opening to us all- to replicate this study and seeing the effect of using ACTUALY PROPEL TIPS instead of TADs: for the sole reason that their design intends to cause micro features radiating from insertion point while TADs design intends to prevent them as they need to stay in place under sustained orthodontic forces… I believe it’s not about the perforation itself but how it’s created as well…
    Here are my two cents, been using MOPs since 2012 and have seen remarkable results!

  10. Dear Dr. OBrien: Propel KOL here. With a great deal of respect for you (And The Who!) there is a fundamental flaw in this study. The authors have made the profound error of equating a perforation created by a TAD with that made by a MOP instrument from Propel. They are NOT equivalent. The TAD screw is designed to go in (and out) with minimal disruption of the hard tissue, and stay there peacefully until its role is complete. The true MOP screw is quite the opposite: it is designed to go in and create all kinds of disruption: THAT is what initiates its accelerative effect (inflammation, cytokine recruitment, osteoclast activation.) This effect can be likened to a stone hitting a windshield and creating cracks in the glass well beyond the site of impact. A TAD must not do this. I am absolutely not surprised therefore that no difference was found: the two systems HAVE to be be different from each other. I would say to the authors: “repeat the study” with an actual MOP screw- except that it has already been done by Alikhani et al and published in the same journal in 2013. We all want to “Not get fooled again,” but if we “substitute” and apple for an orange- I can see the glaring error for “miles and miles. ” The Kids are Alright” when the correct tool is employed.

  11. Dr. O’Brien:
    I am surprised that you would consider such a study for review when the efficacy of MOP was investigated using a TAD, let alone an Aarhus mini screw, known to be one of the best in the industry designed for maximize pull-out force and to minimize micro-fractures and inflammatory responses. Use of this TAD in the study underlines the authors failure to understand the biochemical and physiologic basis for MOP. The MOP device is specifically designed to create exactly what TADS are designed to avoid.
    Moreover, the authors stated that “the mini screw was inserted 3-4mm deep to account for soft tissue thickness of 2-3mm”. According to Jin et al., JPIS 2012, the average cortical thickness of bone distal to maxillary canines at 3mm & 5mm fron the CEJ, and at the apex is 1.5-2.0mm, with a maximum possible of 3.3 -4.5mm. The authors stated depth suggests that the penetration quite possible did not traverse the cortical bone, which is critical to effect the desired micro fracture result. In addition, while their intent was to parallel the Alikani study, the authors elected to apply a retraction force of 150gms as opposed to Alikani’s 100gms, a considerably greater force in light of the understanding that lighter, continuous forces produce greater OTM.( I was under the impression that the point was to replicate Alikani’s work.) Finally, the authors measured the force initially but failed to measure it at subsequent appointments. While I appreciate your presumably tongue-in -cheek title reference to the Who with “We won’t get fooled again?”, I think it would have been more appropriate to have referenced Aretha Franklin with the title “Who’s zoomin who?”

  12. Once again, denial is not just a river in Egypt. While the prop(el)onents would have us go to rather extreme lengths to suspend disbelief and embrace fallacy, the onus is on the ones who make the claim to provide evidence. One has to wonder why the Alikhani paper measured canine retraction for only 28 days. What happened at the end of retraction? Why were those results not published? Could it be because there were no clinically significant differences in the rate of retraction btw the two groups? It is quite delusional to embrace this degree of cognitive bias given the lack of evidence and now the evidence of absence of an effect. Does the osteoclast know the brand of screw that it responds to?

    • *Sigh*

      Another individual who enjoys how he sounds and embraces attempts at wit rather than be concerned about validity.

      In your parlance an osteoclast does not know the brand of screw it responds to but what it will register the nature of the mechanical injury.

      Thus if the disruption of a same diameter burr or screw is sufficiently different the inflammatory mileu may be different and possibly contribute to differences in clinical outcome.

      Here is a picture of the Aarhus TADs with threads design clearly visible


      Propel quote “Optimal Torque and Speed for MOPs” thus the torque and speed for the performance of these “MOPS”,which are actually TADs inserted in a MOP like fashion should have been quantified.

      They do not even state what the driving mechanism was.

      If they considered the insertional portion to sufficiently similar they should have outline there reasoning and basic experimental comparisions.

      They would have done better had they purchased the Propel hand piece and compared it to a TAD group.

      A poor paper to refute the value of MOPs which are by definition delivered by the Propel system. A basic mechanical characteristic comparison would have increased the inferential value of the paper.

      You will note Kevin even raised this concern:

      “Interestingly, they applied the MOP with mini-screws. However, I was not sure how this differs from using the Propel device. I think that both methods seem to cause the same amount of localised trauma. Perhaps a Propel advocate or Key Opinion Leader could help us here?”

      If you are going to refute a technique or system especially the in Wild West of dental devices where the threshod for adoption seems to be lower and less critical than their medical counterparts the study must be appropriately geared to support that refutation.

      Instead I see pointless papers lacking in basic understanding of the scientific method and equally pointless commentators such as Fenris Ulfr.

      He who engages in strawman and distractionary arguments when challenged with propositions he does not take fancy to, rather than enaging in appropriate discourse at the crux of the matter (I also take reference of your other comments on this blog). And yet presents himself as a thinking man par excellence.

      I know any first year student in the Philosphy of Logic would without sweat at the brow dismiss much of your reasoning and conclusion as evidencing clear bias and thus merely pontification reflecting the absence of sound reasoning.

      But by all means continue to make jokes about a river in Egypt as it serves you and the readers of this blog well. Or does it?

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