October 22, 2018

MOPs speeds up tooth movement according to this new trial!


We all would like to speed up the rate of tooth movement. This new trial shows that Micro osteo-perforation (MOP) speeds up tooth movement.

Recently, investigators have carried out several trials to evaluate methods of attempting to speed up tooth movement. One of these methods is micro-osteoperforation or MOPs. In this technique, small holes are made in the alveolar bone. This then results in regionally accelerated phenomenon or RAP. I have posted about trials that have looked at this before. I pointed out that there is limited evidence of a clinically significant effect on the rate of tooth movement.  This is an interesting and clinically relevant area of orthodontic research. I was, therefore, very interested to see this new trial.

A team from India did this study. The Journal of Orthodontics published it.


Sonal Attri et al

Journal of Orthodontics: https://doi.org/10.1080/14653125.2018.1528746

They set out to ask this question;

“Does MOPs influence the rate of tooth movement and pain when used for en masse retraction”?

What did they do?

They did a 2 arm parallel allocation randomised clinical trial with an allocation ratio of 1:1. They registered the trial.

The PICO was:

Participants:Orthodontic patients aged 13-20 years with an irregularity index of <3mm. They had extraction of mandibular and maxillary first premolars and needed en masse retraction for space closure.

Intervention:MOP using the Propel device. They did this at the start of space closure and then every 28 days until the extraction spaces were closed.

Control:Space closure without MOP.

Outcome:Rate of space closure in mm/month. They measured this on digital models. They recorded pain perception with a visual analogue scale 24 hours after MOP, 7 days and 28 days after MOP.

I thought that other important areas of their methodology were:

They closed space on a 19×25 ss wire using a standardised force of 150g on each side of the arch.

They started the retraction immediately following the MOP.

Anchorage preparation was done by banding the second molars and fitting a palatal arch.

They measured the space closure by drawing a mid palatal line on the software. They then drew perpendicular lines towards the distal surface of the canine to the mesial surface of the second premolar. This was the amount of space closure.

They did a clear sample size calculation, data collection was blinded, randomisation and concealment was good.

What did they find?

60 participants entered and completed the study. There were no differences between the treatment groups at the start of treatment.

I have extracted the relevant data on rate of space closure in mm/28 days, into this table.

Space MOP No MOP Difference (95% CI)
Upper right 0.89 (0.17) 0.63 (0.11) 0.25 (0.18-0.33)
Upper left 0.88 (0.21) 0.53 (0.19) 0.35 (0.25-0.45)
Lower right 0.8 (0.19) 0.53 (0.1) 0.27 (0.19-0.35)
Lower left 0.73 (0.1) 0.49 (0.1) 0.24 (0.17-0.31)

All these differences were statistically significant. They did not detect any difference in pain perception.

Their overall conclusion was:

“There is a definite enhancement of orthodontic tooth movement when MOP is done before starting tooth movement”.

What did I think?

I thought that this was a well-done small study.  I also thought that their results were interesting. However, we need to consider whether the effect size was clinically significant. This is for you to decide.

I thought that a good way to approach their data was to look at the effect that these differences may have on the overall time for space closure.  For example, if we look at the greatest difference, which is space closure on the upper right first premolar space.  They reported that the average pre-treatment space in the maxilla was 5.0mm. If we take an average space closure of 0.89mm/month for the MOP and 0.63 mm/month for no MOP. Then the average time to space closure would be 5.6 months for the MOP and 7.9 for the no MOP group.  I feel that these differences are clinically significant.

However, I have a word of caution. We need to remember that they only looked a space closure. I am not sure that we can extrapolate this finding to suggest that we can reduce courses of treatment by 2 months. As a result, while the results are interesting, we still need to see a study that has evaluated the effects of MOPs over the whole course of orthodontic treatment. This, of course, will involve a substantial increase in the burden of care and we would be looking for a substantial difference to justify this?

Several investigators have now done studies on MOP and I am going to do a post in the next weeks to try to summarise the overall evidence for this technique.


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Have your say!

  1. It wasn’t clear from the write up whether the MOP was done just in the extraction space or between all 6 anterior tooth roots.

    Also, another great trial for MOP would be a similar population group and then posterior MOP to blow anchorage.

  2. When statistical/clinical significance is squeezed out of a study, a fully informed patient would have to know how much of a reduction in overall treatment time he/she can expect. Given this information, my data would argue that the average patient would be unwilling to pay much for what is a relatively small, uncertain reduction in time. Indeed, I would wager that patients faced with the usual extra cost would expect a reduction in treatment time many times the actual effect.

  3. What about the adverse effects? The evidence is inconclusive.
    In animals corticotomy increased OIIRR.(1) But in humans few complications and low morbidity were found. (2)
    1. Haugland L, Kristensen KD, Lie SA, Vandevska-Radunovic V. The effect of biologic factors and adjunctive therapies on orthodontically induced inflammatory root resorption: A systematic review and meta-analysis. Eur J Orthod 2018; 40: 326–336.
    2. 1 Gil APS, Haas OL, Méndez-Manjón I, Masiá-Gridilla J, Valls-Ontañón A, Hernández-Alfaro F et al. Alveolar corticotomies for accelerated orthodontics: A systematic review. J Cranio-Maxillofacial Surg 2018; 46: 398–412.

  4. Kevin. Thanks again for visiting topics that remain expensive and “cloudy” to practicing orthodontists in an objective manner. In this case I tend to agree with Lysle. I use MOPS (although they obviously are not “micro”) when a tooth is “stubborn” and then rarely charge the patient. Although those segments tend to catch up with “normal” movements for those patients, my internal analysis is that greater benefits in reducing treatment time lie in eliminating clinical errors and close attention to scheduling intervals. My average time in treatment in fixed appliances for all patients debonded over the course of the past year is 14 months, with the range from 8-36 months, with most of the longer treatment times due to impacted canines. It seems to me the excitement over “accelerated” tooth movement is oftentimes overshadowed by general clinical inefficiencies.

  5. I also totally agree with L.E.johnston and david paquette and MOP is not a panacea for clinical inefficiencies and inappropriate biomechanics you resort to. Two months as opposed to 14 – 18 month might not be that signifcant for most of our orthodiontic patients. But still it might have a place inselected csaes where we have a given target by the patient.

    • I requested a copy of the complete article from our AAO Library in St. Louis back in October and was informed that it had not been published, but they would forward a copy to me as soon as it was published. Apparently a complete article has not been published as I have yet to receive a copy. Hopefully the a complete article gets published soon complete with photos that help us evaluate the claims.

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