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Occlusal adjustment for treating and preventing temporomandibular joint disorders

From The Cochrane Library

Occlusal adjustment for treating and preventing temporomandibular joint disorders

Authors: Holy Koh, Peter Robinson
Editorial Group: Cochrane Oral Health Group
Published Online: 20 JAN 2003
Assessed as up-to-date: 12 NOV 2002
DOI: 10.1002/14651858.CD003812



There has been a long history of using occlusal adjustment in the management of temporomandibular disorders (TMD). It is not clear if occlusal adjustment is effective in treating TMD.


To assess the effectiveness of occlusal adjustment for treating TMD in adults and preventing TMD.

Search methods

We searched the Cochrane Oral Health Group’s Trials Register (April 2002); the Cochrane Central Register of Controlled Trials (CENTRAL) (The Cochrane Library 2002, Issue 2); MEDLINE (1966 to 8th April 2002); EMBASE (1980 to 8th April 2002) and handsearched journals of particular importance to this review.

Additional reports were identified from the reference lists of retrieved reports and from review articles of treating TMD. There were no language restrictions. Unpublished reports or abstracts were considered from the SIGLE database.

Selection criteria

All randomised or quasi-randomised controlled trials (RCTs) comparing occlusal adjustment to placebo, reassurance or no treatment in adults with TMD. The outcomes were global measures of symptoms, pain, headache and limitation of movement.

Data collection and analysis

Data were independently extracted, in duplicate, by two review authors (Holy Koh (HK) and Peter G Robinson (PR)). Authors were contacted for details of randomisation and withdrawals and a quality assessment was carried out. The Cochrane Collaboration’s statistical guidelines were followed and risk ratios calculated using random-effects models where significant heterogeneity was detected (P < 0.1).

Main results

Over 660 trials were identified by the initial search. Six of these trials, which reported results from a total of 392 patients, were suitable for inclusion in the review. From the data provided in the published reports, symptom-based outcomes were extracted from trials on treatment. Data on incidence of symptoms were extracted from trials on prevention. Neither showed any difference between occlusal adjustment and control groups.

Authors’ conclusions

There is an absence of evidence, from RCTs, that occlusal adjustment treats or prevents TMD. Occlusal adjustment cannot be recommended for the management or prevention of TMD. Future trials should use standardised diagnostic criteria and outcome measures when evaluating TMD.


Plain language summary

Occlusal adjustment for treating and preventing temporomandibular joint disorders

No strong evidence of benefit from occlusal adjustment (adjusting the teeth’s biting surfaces) for problems associated with the joint between the lower jaw and skull.

When the joint between the lower jaw and the base of the skull is not working well (temporomandibular disorders (TMD)), it can lead to abnormal jaw movement or locking, noises (clicking or grating), muscle spasms, tenderness or pain. TMD is very common, and might be caused by occlusion (the way the teeth bite), trauma or stress. Treatments include occlusal adjustment, splints, physiotherapy and surgery. Occlusal adjustment involves adjusting the biting surface of teeth by grinding the enamel (outer layer of the tooth). The review found there is no evidence from trials to show that occlusal adjustment can prevent or relieve temporomandibular disorders.

Questions et commentaires

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  1. Valérie Roy says:

    I invite you to look through Dr Peter E. Dawson’s researches, who devoted his career to occlusion. His researches will maybe change preconceived ideas on the latter. Moreover, you will be able to consult Dr Mark Piper’s work who, because of extensive assessment of TMJ MRI, explores TMD in a lot more details. Huge breakthroughs that are unfortunately still not well known.

  2. Good morning Dre Roy,

    I apologize for taking so long to answer. I was busy in the last few days.

    I take note of your comment about “preconceived ideas”. An exhaustive research published in the Cochrane library was precisely performed to find an answer to the preconceived idea that occlusal adjustments can treat or prevent symptoms or temporomandibular disorders.

    But let’s first differentiate two concepts:

    1-Experience-based view.

    Clinical experience and years of experience are the only important things for the practitioner. Usefulness of science is often denied. Anecdotal evidences are sufficient to make a clinical decision and are better than science. TMD diagnosis is based on meticulous analysis of occlusion. Recommendation is to use occlusion protected by the canine. Any position of the condyle other than supero-antero-medial position causes TMD. The use of articulators in orthodontics is favored.

    2-Evidence-based view.

    Science and scientific method are important to the practitioner. Benefit and usefulness of science are proven. Testimonies, case studies and non-objective experience are inadequate or insufficient to make a clinical decision. No definitive tests exist in TMD diagnosis. The gold standard for diagnosis is based on case story, clinical examination and TMJ imaging when indicated. Occlusion is not the main cause of TMD, but possibly plays a minor role in its etiology. TMD are a whole, a collection of disorders. The position of the condyle per se is not directly associated with TMD. Biological concept of a functional occlusion includes all kinds of occlusion (group function or canine guidance) but not occlusal interferences (balancing and protusion contacts are tolerated). Articulators are not necessary in orthodontics.

    Rinchuse DJ, and Kandasamy S. Evidence-based versus experience based views on occlusion and TMD. AJODO 2005, feb;127(2):249-54

    I would like to point out that even if I am a practitioner cumulating 30 years of experience, I am part of those who believe in evidence-based dentistry.

    Hierarchy of quality of scientific evidence

    Hierarchy of scientific evidences-Dr Chamberland orthodontist in Quebec City Drs Peter Dawson and Mark Piper‘s researches and work have to be placed, like it or not, in the “unsupported opinion of expert” category, at the bottom of the scale of scientific evidence. Holy Koh and Peter Robinson‘s article on occlusal adjustments from the Cochrane library is located at the top of the scale along with meta-analysis including multiple trials. I invite you to read the whole article: Occlusal adjustment for treating and preventing temporomandibular joint disorders (Review)

    It is interesting to note that none of Drs Dawson and Piper’s research work was selected in this meta-analysis. It is likely to believe that their work didn’t meet the high selection criteria and absence of bias to be considered and included in the meta-analysis.


    Mark Piper and “Piperism”

    A very good example of preconceived idea is provided to us by Dr Mark Piper when he describes TMJ avascular necrosis by saying that compression of the TMJ perforating blood vessels occurred. He tries to link avascular necrosis caused by a fracture and collapse of the femoral head where a main artery and branches of lateral and medial circumflex femoral artery are located.

    Femoral artery-Dr Chamberland orthodontist in Quebec City
    TMJ Piper-Dr Chamberland orthodontist in Quebec City

    He pretends that anterior disc displacement compresses “so-called” TMJ perforating blood vessels and causes avascular necrosis of the condyle.

    But this artery does not exist.

    Piper uses avascular necrosis concept to promote his microsurgery technique where he perforates the head of the condyle to promote vascularization.
    He showed histological bone cuts that he removed during these perforations while saying that “his pathologists” said that it was “dead” bone.
    But when these samples were re-analyzed by independent and renowned pathologists, they all showed that the bone was alive and they refuted his whole avascular necrosis concept, which scientifically put an end to the discussion.
    Piper’s results concerning the use of adipose tissue grafts to treat TMJ internal derangements and condylar resorption were never published in any renowned journal where articles are revised by peers before publication (peer-review journal). To this day, nobody has published an article showing that someone had been able to reproduce Piper’s results.

    Definition of reproducibility in science

    Reproducibility is the degree of similarity between measures or observations when reproducing a procedure, an experience, an analysis by different people in different places (hospitals, universities, countries). Reproducibility is part of the precision of the tested method.

    Arterial blood supply of the TMJ

    TMJ arterial blood supply Artery LMercury-Dr Chamberland orthodontist in Quebec City

    Arterial blood supply of the TMJ comes from multiple sources (external pterygoid muscle, cancellous bone, internal pterygoid muscle, posterior attachment vessels and transverse facial artery). Anybody having performed a surgery on a TMJ knows that blood supply comes from multiple sources. See the attached picture showing the arterial network and see Dr Carl Bouchard’s video clip while he performs a costochondral graft on one of my patients. Notice the hemorrhage when he unfortunately cuts a small artery when working on the left side (CCG link).

    The Québec Association of Orthodontists recently invited Dr Alain Aubé to hear his point of view on TMJ. Let’s say that several colleagues from the Association expressed huge hesitations against the concepts conveyed by Dr Aubé. Numerous sophisms were noticed. We witnessed a display of preconceived ideas like we had rarely seen in a continuing education course.

    We do not deny the use of magnetic resonance imaging in some TMJ pathologies, such as disc displacement, but diagnosis of TMD cannot be limited to magnetic resonance imaging.

    Treatments of TMD have to rely on scientific basis.


    The mistake to avoid is to put occlusion at the center of all TMJ problems and believe that the solution to TMJ problems is through only one functional occlusion model with canine guidance and bilateral contacts equally adjusted to 8-micron shimstocks.

    Prevalence of Class I, Class II or Class III malocclusions is about equally distributed between men and women. Dismorphism is not based on gender.

    Differences in types of malocclusions (Class I, Class II or Class III) exist depending on the population observed: white (Caucasian), Afro-American, Asian or Hispanic.

    Incidence of TMD in the population in general is of 2 women for one man.

    Incidence of patients suffering from TMD is of 10 women for one man.

    Dr Larry Wolford (Atlas Oral Maxfacial Surgery Clin N Am 19 (2011) 243-270), in a research comprising 1369 consecutive patients from 8 to 76 years of age referred for TMD, observed a proportion of 78% of women and 22% of men. 69% of affected patients mention that their problem started in their teenage years. He concludes that TMD mainly develop in teenage girls.

    We can think about the following:

    If occlusion were the cause, it is likely to pretend that the M-F distribution would be more balanced.

    In this context, isn’t it unlikely to pretend that occlusal adjustment prevents TMD knowing that women are more affected by this kind of problem and that there are no differences between men and women in prevalence of malocclusions?

    In conclusion, I will quote Dr Louis Mercuri:

    “It is essential that TMJ osteoarthritis be presented as the pathologic entity it is in the same terms as our colleagues discuss osteoarthritis in orthopaedic circles.

    To not do this only exacerbates the problem that everyone dealing with this entity patients, clinicians, insurance carriers, and so forth has with TMJ osteoarthritis, because they do not consider it as the orthopaedic (medical) pathology that it is, but rather a purely dental TMJ problem.”

    L.G. Mercuri Oral Max Surg Clin N Am 20 (2008) 169-183


    Finally, I recommend to you the excellent book from Drs Charles Greene and Daniel Laskin which was just released to rectify a lot of your preconceived ideas that were transmitted to you by Drs Dawson and Piper.

    Treatment of TMDs:
    Bridging the gap between advances in research and clinical patient management
    , ©2013 Quintescence Publishing Co.

    1. Congratulations Dr Chamberland for this exhaustive reply but nonetheless very clear on several points of view.

      I believed for several years that occlusion was a major factor in TMDs. I thus can have some empathy for all these dentists who believe this myth a lot.
      It is a little sad, of course, to see that some of us become such fanatics that they even plan conferences and invite physicians, physiotherapists, chiropractors, radiologists, etc., etc., etc. Even there, I can understand.

      Unfortunately, these different healthcare professionals are rarely aware of the importance of the scale of scientific evidence, even less of the different levels of evidences and what else to say about their capacity to criticize objectively a conference on dental occlusion while they know nothing about dentistry???

      Nevertheless, it is possible that the speaker himself is aware of this ignorance and takes advantage of it by using logic, mythical beliefs, numbers to orchestrate everything well with some speaker charisma to “catch” disciples, making it easier to enlarge the group and provide additional support to the so-called philosophy (open question).
      Unfortunately, if we do not want to lose our profession and bring it to the level of alternative medicines, we must object to all of these philosophers of occlusion in great numbers.
      Having completed several of these philosophies of occlusion (Skavicek, Dawson, neuromuscular) myself, I was fortunate to become confused enough to go back to school and understand the importance of this famous scale of scientific evidence. I believe that the recent report released by the ODQ is an excellent first step in the right direction; unfortunately, I notice through my training seminars that there are still just a few rare dentists who know about this report. It is still an excellent initiative from the ODQ to protect the public against these PHILOSOPHERS.

      Some of the dentists who register for my training seminars also (unfortunately) have taken a lot of these training seminars. Kudos to those who, despite dozens of thousands of dollars invested, still had the courage to come back on the right path (the one guided by the scale rather than mythical beliefs of a GURU).

      We thus still have a lot of work to do but more and more dentists are aware of this scale. Several new graduates are aware of this scale and they will be a lot harder to recruit, “catch”, be convinced by GURUS.

      Let’s continue to work in that sense, our profession will benefit from it in the end.

      Dr Yves Gagnon, prosthodontist.

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