June 25, 2018

Expansion with Damon appliances results in buccal bone loss?

The wheels of the extraction/non-extraction debate continue to spin. This study highlights a problem with non-extraction expansion treatment.i

Since the early days of orthodontic treatment, we have been debating the need to extract teeth.  This has resulted in confusion, lengthy discussion and changing extraction patterns over time.  Recently, orthodontists have been extracting less teeth. This has been a result of by non-evidenced based discussion, social media driven orthodontics and extreme claims made for the harm that extractions cause.  For example, it has been claimed that extractions harm the airway, cause bed wetting, damage the profile and we are removing perfectly good body parts.

The only true theme that surrounds this situation is the lack of evidence that supports these claims. When we look at research, there does not seem to be any harmful effects of extractions as part of a well planned and executed orthodontic treatment.  Nevertheless, the wheel of this debate was given another spin by the claims made by the promoters of non extraction self ligation appliances.  This was that the use of self ligating brackets, to expand arches, resulted in expansion with the development of new bone.

A team from Brazil and Denmark did this study. The Angle Orthodontist published the paper.

A cone beam computed tomographic study

Juliana F. Morais et al

Angle Orthodontist: On line.  DOI: 10.2319/101117-686.1

 

They set out to ask this question:

“What were the changes in the maxillary alveolar bone during the alignment phase of non extraction treatment with a self ligating appliance”?

What did they do?

They did a prospective cohort study. The PICO was:

Participants: Twenty two orthodontic patients aged 11-17 years old with more than 4 mm of crowding.

Intervention: Non extraction treatment with Damon3MX brackets with a standard “Damon” arch wire sequence.

Comparator: Non.

Outcome: Analysis of buccal bone using CBCT scans that were taken at the start of treatment and 4 weeks after the insertion of the final 19×25 ss archwires.

They analysed the CBCT scans to measure the following:

  • Buccal bone thickness at 3 and 6mm from the CEJ
  • The buccal bone area
  • Buccal bone height, this was defined as the distance from the CEJ to the alveolar crest.

They also measure, expansion, rotations of teeth and amount of tip of the teeth.

Finally, they did some simple univariate statistics across the variables. They also looked at associations between initial bone morphology, amount of tipping and initial crowding on the buccal bone data.

What did they find?

All the patients completed the study. The mean age of the patients was 14.7 years and the mean Little’s index of the maxillary teeth was 11.3 (SD=5.2).  When they looked at the buccal bone measurements they found the following:

There was a decrease in both the buccal bone thickness of 0.2mm (23%) and bone area of -1.2 mm (13%) for the incisors. There were similar losses for the molars. They also showed that there was significant apical migration of marginal bone at the incisors (0.4mm) and molars (0.3mm). Finally, more that 20% of the patients had bone recession measuring greater than 1mm related to one tooth or more.  We need to decide ourselves whether these are clinically significant effects.

The maxillary arch widths increased and this was associated with significant buccal tipping. There was also incisor proclination of 2.1mm.

They concluded that the crowding was alleviated by maxillary tooth tipping and that the teeth “moved through the bone” and did not “remain centred in the bone” with development of the alveolar bone.  That is the appliances did not make the bone grow.

What did I think?

I thought that this was an interesting small study that provided us with useful information. However, we need to take care with the interpretation of this data. This is because there was no comparison group. The ideal study would be a trial in which patients were randomised to treatment with with expansion/self ligation brackets or extraction and conventional brackets.   As a result, we cannot conclude that expansion with self-ligating brackets results in loss of alveolar bone any more than conventional extraction treatment. Indeed, there are studies that show bone loss with extraction treatment. Nevertheless, I feel that we can conclude that there is absence of evidence that non-extraction expansion treatment with Damon brackets, or any other bracket, develops the alveolar bone. The Damon and non-extraction story continues….

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Have your say!

  1. Avatar

    What was the reliability and accuracy of the measurements. As some of the stated changes are 0.2mm and the voxel size lily was 0.25mm then the level of certainty in those measurements is arguable.
    The level of precision of CBCT measurement for such. minute changes may not exist yet.

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    I have an Orthodontist in my area who has been a Damon disciple since the beginning.. I now am seeing the results in her 30 y/o patients.. I’m not saying ALL just saying many I see have significant recession of buccal gingiva.. much more than I find with my patients. Her philosophy for years was magic Damon brackets removed the necessity of skeletal expansion and other Orthodontists were old fashioned

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    Hi Kevin,
    I have a question in term of the timing of the 2nd CBCT. It is only 4 weeks after the final archwire and not at debond when there is no more active orthodontic movement. The Damon proponent can argue that as there is no damage of the cementum, alveolar bone will develop on the buccal surface and right now there is just not enough calcium deposit so that we don’t see the buccal bone in the CBCT. I am not an expansionist, just playing devil’s advocate.
    Bennett

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    “Proclining incisors is suicide”—Hayes Nance 1947 AJO

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    Bennett, you bring up an excellent point, as an orthodontist that would routinely take progress cephs and pans, the timing was never an issue since the focal troughs of these 2D radiographs were enormous. CBCT is a different animal. The focal troughs are usually 0.2-0.5 mm and will not pick up bone that is in the process of being “remodeled”. I believe it is good policy to wait 3-4 months before taking post active orthodontic CBCT . I also believe that this argument applies more to roots that are maintained within the alveolar housing and not dehiscessed thru the cortical plate. If you have any doubt about the damage excessive expansion orthodontic treatment can cause, please take a look at Alveolar Focused Orthodontics, Part 3 of 5. I show a case that was treated with Damon, the CBCT was taken 3 years post active orthodontic treatment (certainly enough time for bone to fill in). This patient unfortunately lost 2/3rds of the buccal bone on 14 of the 28 erupted permanent teeth (via Oral Maxiofacial Radiologist Report). Traditional orthodontics (6 Keys to Normal Occlusion) says not to indiscriminately expand the arch. Although the non-expansionist crowd seems to be on the defense, I believe these CCM’s (Clinical Crown Mechanics (only concerned with alignment of the clinical crowns) need to show reliable research that supports this treatment philosophy of non extraction and not the other way around. I also find it interesting that Damon uses proof of “bone remodeling” by showing post treatment CBCT. Try to find a single post treatment CBCT on the Damon website Gallery cases. Every post treatment CBCT I have seen with the Damon system has showed excessive buccal root dehiscence. I provided link to this Damon case. Watch the video and make up your own mind. jeff

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      As a 35 year practitioner of the Tweed-Merrifield philosophy I want to commend you on your understanding and presentation of the dimensions of the dentition. We have subscribed to this philosophy since the time of Charlie Tweed. It’s a shame that science is relegated to commercialism and greed.

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    Kevin,

    When I first saw the subject line of this blog, I took in a very deep breath thinking that here we go, Kevin is going to take another stick to the Damon self-ligating system. After reading your piece, I was relieved to realise that you have been magisterial in your review, as an evidence-seeking orthodontist should. This paper is just another anecdote with a clutch of patients without a properly designed trial and an exact study using standard Edgewise (or Begg bracket) would and should elicit the same remarks from you. Why are we wasting our time debating publications that do not meet our requirements for a scientific study? Just to get more papers to support academic careers? There is a debate among the top journals in science that we should consider imposing a lifetime word limit to every academic’s papers. This wiill help address the reproducibility crisis in science and to improve the quality of publications. Finally, I declare a conflict here, I have been using Damon brackets for 15 years and apart from its utility as just another bracket, I do not believe there is any biology behind the protagonist’s claims about growing the bone or waking up the tongue. Wish it would.

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    Valid caveats have been mentioned in the comments regarding a) voxel size, and b) insufficient time allowed for bone remodeling, and that conclusions should not be drawn with bone measurement differences within or near the range of the voxel size itself. Furthermore, built into those concerns arise a couple other noteworthy points. One is partial volume averaging artifact (PVA) in CBCT, where border regions show bone to be thicker or thinner than true dimensions(due to image reconstruction averaging densities of stark difference where they intersect within a voxel), and for very thin bone (such as buccal bone), PVA can wash out the appearance of bone that is truly present. In other words, if you see it clearly, it is there, but if you do not see it, it doesn’t mean it is not there. The other consideration is artifact from beam hardening and scatter from brackets and wires. Although these are typically more limited to the plane in which the image acquisition process occurs (usually within the axial slice ranges of the material in question), it could easily affect nearby bone readings. Both of these features might be more susceptible to cause unreliable measurements in scans with dose-sparing protocols as used in this study. The authors did mention why they used this protocol as it was more clinically appropriate, but the in-treatment measurement was surely premature. A well-written, succinct article addresses these points as well as recommending that bone measurement studies have a image acquisition time point of at least one year post treatment for better reliability, and elucidates upon some of the potential misinterpretation of bone measurement studies in orthodontics (Molen AD. Considerations in the use of cone-beam computed tomography for buccal bone measurements. Am J Orthod Dentofacial Orthop. 2010;137:S130–S135). Interesting study nonetheless. The question, if the results hold, is whether we as a profession are willing to trade gingival recession for other possible more serious adverse effects IF, for example, our professional calculation guides us to be more cautious with the airway and oral cavity volume or what not, if we see clear morphological pre-treatment airway compromise (this is simply an example of a case-by-case consideration, not a blanket statement that airway compromise is related to extraction or anything). No life has been threatened by a gingival recession of 0.2-1.2 mm.

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    A far bigger issue is the cranio mandibular disorder induced by distalised mandibles . Agreed there may well be a small amount of recession . So balance this with instant loss of 4 teeth for extraction , and potential atypical facial pain/dental distress syndrome, when older. I’ve been expanding large amounts for 25 years and reviewing my own patients, as a gdp. I don’t see recession routinely, if at all. But good artical Kevin. Its good to stir the pot!
    Its all a compromise somewhere , what ever we do .

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      On a purely anecdotal basis and with no rigid science basis ,I totally agree with the previous post from Peter.
      The only major cases of expansive related bone loss ,I have seen ,were related to RPE use.
      As an aside ,I have dealt with many complex pain issues initiated by RPE use ,which were very difficult to treat and render pain free.
      I feel that there were some negative osteopathic issues at play and wonder if others have had similar experiences ??
      Thankyou.

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    This paper shed the light on the crucial issue,which is:the range of orthodontic tooth movement, whatever the system if fixed appliance used in orthodontic tooth movement, the range of tooth movement is the question. Moreover the stability of treatment is another topic correlate with the above discussed subject.

    As Dr O’Brien has mentioned, there is no evidence that extraction will cause harmful effect if planed and

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    This article, review, and ensuing discussion highlights the need to be much more specific about what the word “expansion” actually means, or be specific about what it is we are talking about being “expanded”.

    I was taught that expansion specifically referred to widening the maxillary suture. Now, expansion can refer to a wide variety of changes that orthodontists subject the maxillary teeth and bones to.

    The term expansions seems to refer to Alveolar expansion, Arch perimeter increase by buccal tipping of the teeth, as well as sutural expansion. All of these things describe very different processes. Even more obtuse is the undefined term “Arch Development” which has no orthodontic definition or research foundation. This article seems to show that increasing the arch perimeter can and does move teeth beyond the boundary that Dentistry uses to define dental health. This is not expansion, but rather bad treatment hiding behind the acceptable mantle of expansion.

    Let’s stop using the word Expansion to mean anything other than increase in the width of the suture. This would be a step in the right direction and allow healthy, accurate discussion of what is actually happening to patients with various modes of treatment.

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    Recession, Schmesession. Cranio mandibular disorders and atypical facial pain/dental distress syndrome are the least of our concerns. Fact – 100% of all patients who have premolars extracted will die!

    We should be expanding arches until the alveolar bone is a pale, shadowy memory. The buccinator, labii superioris and mentalis are perfectly suited to support the teeth. This will allow the tongue to wake up and reach it’s full potential (hang down to the chin).

    We can provide our patients with “droolcups” and other equine accouterments to accompany their new grimacing countenance. Let’s not talk about the instant loss of four teeth, but instead let’s turn our attention to face-focused Atavistic© orthodontics. With light, gentle forces (as we whisper soothing sweet nothings to the bracket), physics, biology, logic and sanity can all be overcome to provide a gradual return to our hominid ancestors. Let’s harken back to the past when there was no face flattening, sleep apnea, TMJ disorders or electricity! We must never, ever let facts get in the way.

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    Kevin ..you always are marvelous!

  13. Avatar

    kevin, you always are marvelous…a very good work!

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    Dear Kevin

    Dr Jeffrey Miller is absolutely right; there is, and has been for a long time, insufficient attention paid to the dental bone.

    I am mystified by the apparent inability of so many brilliant dental minds to understand the problem.

    FACT: If you attach a bracket and wire system to the buccal or labial aspects of a bunch of teeth and them pull on it in a radial direction, it is not surprising that the teeth sometimes come out through the thin bony plate! The process almost amounts to partial bucco-labial extraction!

    FACT: The sensible approach is to address any extant bony issues first; expand/grow/ develop the maxilla and mandible until there is sufficient space and arch length to accommodate all the teeth by encouraging the bone to grow bucco/labially, carrying the teeth with the growth. Any mal-positioned teeth can then be easily corrected in a few months if required.

    FACT: We are genetically programmed to grow up with 32 teeth. We are provided with those 32 permanent tooth buds at birth. They are supposed to last for our entire life. Yet some orthodontists see it as acceptable to remove 4 or more perfectly good teeth in order to facilitate straightening the rest of the teeth quickly and easily. The issue of inadequate bone is ignored.

    FACT: Crooked teeth are not the problem; they are the result of the problem. The actual problem lies in the inadequate or distorted dental bones, which are all, of course, physically linked to the cranial bones.

    FACT: Until this is fully understood and taught to students, conventional orthodontics will remain a very questionable subject.

    FACT: The current official advice given by the GDC and the BOS is that if post-treatment relapse is to be avoided, retention must be life-long. I view this as the most damming indictment of our profession and I know of no other branch of medicine and health care that would dare to hand out similar advice.

    Noel Stimson

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    Dear Kevin – Here are a few other facts to add to the mix.

    FACT: The maxilla and the mandible can be expanded limitlessly! The invisible intermandibular suture is just waiting to feel a sensible approach applied to it. Bone apposition occurs in every direction a tooth is moved. No such thing as a pressure & tension side. Dehiscences and fenestrations are figments of an over-active imagination

    FACT: Premolar extractions are facial mutilation! We are actually genetically programmed to have 40 teeth. Once we expand and procline the teeth beyond the labial confines, the additional teeth (always premolars) can then be added via a process called Premolarogenesis®.This process is easily achieved by using abbreviated appliances.

    FACT: Crooked teeth are the result of a disconnect between the cranio-sacral process, the metopic suture and the blephoid process. Until this is accepted without evidence, we will not be able to reach our full potential to levitate.

    FACT: Although there have been numerous studies that disprove all our theories, we must strive to ignore all that evidence. The only thing that matters is what we feel, despite data to the contrary. We must ignore facial balance, esthetics, stability, periodontal and TMJ health, and occlusion in our quest for a 40-tooth smile. If we add 25% more tooth mass to the mouth, we might be able to fly as velociraptors used to.

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      Dear Kevin

      If orthodontists wish to bury their heads in the sand (presumably with Fenris Ulfr leading) and ignore the changes that our profession is going through, so be it. But these changes are inevitable natural growth and the buried heads will be left behind.

      The reality is that orthodontists and other dentists can have a dramatic effect on patients’ health involving TMD, breathing and airway issues and sleep disorders, etc. Simply being aware of these possible connections can make a difference; to refer appropriately, or treat when possible, renders orthodontics a far more medically-significant profession than simply providing nice (unstable?) even-toothed smiles.

      The reason for the shortage of high quality scientific evidence of this is simple; the vast majority of progressive orthodontists working in this field operate in private general orthodontic or dental practice, outside the hospital/NHS establishment and have neither the time nor the resources to carry out serious scientific studies.

      Noel Stimson

      PS: You seem to have forgotten that two years ago you told me that you would no longer allow blogs from pseudonyms such as Fenris Ulfr.

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    Perhaps Noel can form his own blog where we can discuss alternative facts and other theories with no evidence?? While these practitioners don’t have the time for research, they certainly have enough time to concoct some fascinating theories. We must not stifle debate just because it threatens our point of view. Let Fenris stay.

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    I find it amazing that some practitioners here are saying ‘there is no evidence to suggest that extractions cause harm’ as if theres a paper somewhere which says that ‘there is no evidence amputation of one’s finger’s cause harm’…
    At the end of the day, it is a body part which we are born with and we develop over adolescence. This is where people who become robotic academic journal seeking junkies fail to use common sense. Why would a body part develop if it need not be there? Are none of us interested in perhaps taking the assumption that we should develop the arches so that all the teeth should fit within them? Is it not rational to cast away the assumption that a subjective perception of ‘beauty’ of the teeth is our desired outcome? or rather the aim to attempt to fit all 32 teeth into the mouth?
    Call me crazy but I can’t help but think this is a more common sense approach.

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    What about removal of the appendix or circumcision or extraction of wisdom teeth? Why would they develop if they were not meant to be there? Or for that matter, tumors or cancer? If they formed normally, perhaps we should find a way to develop our lives around these wonderful and natural accouterments to our life.

    And if the alveolus, facial esthetics, stability etc were to get decimated in the quest for “fitting it all”, that’s just subjective then, isn’t it. Common sense, right? Don’t need no journals for that.

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    Hi,This article was too useful .After so many years of orthodontic practice still tre is a dilemma in Extraction and Non extraction treatment .

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