Wednesday, August 24, 2011

Temporomandibular Disorders: A Position Paper of the International College of Cranio-Mandibular Orthopedics (ICCMO)

Cooper, B: The  Journal of Craniomandibular Practice. July 2011, vol 29,No.3, pp. 237-244

Purpose: Two principal schools of thought regarding the etiology and optimal treatment of temporomandibular disorders exist; one physical/functional, the other biopsychosocial. This position paper establishes the scientific basis for the physical/functional. 

The ICCMO Position: Temporomandibular disorders (TMD) comprise a group of musculoskeletal disorders, affecting alterations in the structure and/or function of the temporomandibular joints (TMJ), masticatory muscles, dentition and supporting structures. The initial TMD diagnosis is based on history, clinical examination and imaging, if indicated. Diagnosis is greatly enhanced with physiologic measurement devices, providing objective measurements of the functional status of the masticatory system: TMJs, muscles and dental occlusion. The American Alliance of TMD organizations represent thousands of clinicians involved in the treatment of TMD. The ten basic principles of the Alliance include the following statement: Dental occlusion may have a significant role in TMD; as a cause, precipitant and /or perpetuating factor. Therefore, it can be stated that the overwhelming majority of dentists treating TMD believe dental occlusion plays a major role in predisposition, precipitation and perpetuation. While our membership believes that occlusal treatments most frequently resolve TMD, it is recognized that TMD can be multi faceted and may exist with co-morbid physical or emotional factors that may require therapy by appropriate providers. The International College of Cranio-Mandibular Orthopedics (ICCMO), composed of academic and clinical dentists, believes that TMD has a primary physical/functional basis. Initial conservative and reversible TMD treatment employing a therapeutic neuromuscular orthosis that incorporates relaxed, healthy masticatory muscle function and a stable occlusion is most often successful. This is accomplished using objective measurement technologies and ultra low frequency transcutaneous electrical neural stimulation (TENS). 

Extensive literature substantiates the scientific validity of the physical/functional basis of TMD, efficacy of measurement devices and TENS and their use as aids in diagnosis and in establishing a therapeutic neuromuscular dental occlusion. Clinical Implications: A scientifically valid basis for TMD diagnosis and treatment is presented aiding in therapy.

The overwhelming majority of dentists worldwide, treating thousands of patients annually, and whose patients had not previously experienced resolution of their painful and/or dysfunctional symptoms support the conclusions reached by a large number of studies that TMD is a physical/functional disorder most often resulting from the mal-relationship among the dental occlusion, masticatory muscles, and TM joint function.11-34,39,164 They find that their patients are most often conservatively and successfully treatable initially with reversible occlusal orthosis therapy. Members of ICCMO adhere to this principal and treat to establish a healthy craniomandibular relationship through the use of a physiologically balanced neuromuscular occlusion that is in harmony with relaxed, healthy masticatory muscles with improved function and properly functioning TM joints. This achieves a stable, physiologically sound dental and craniomandibular position that does not cause noxious neural input to the central nervous system with resultant  adaptive/accommodative function and behavior. In addition to its use in the treatment of patients with TMD, the neuromuscular occlusal philosophy can be successfully applied to all forms of dental treatment that involve major alteration of dental occlusion, including orthodontics, full arch or full mouth reconstruction and complete dentures. Successful treatment of temporomandibular disorders using neuromuscular occlusion techniques is directed towards elimination of the cause of the disease, not just symptom relief. If the cause is not successfully identified and treated, the acute physical/physiological form of TMD may unfortunately degenerate into a chronic pain condition, rarely cured, and at best, attempted to be managed with pharmacologic and other medical/ behavioral therapies. Such symptom- only oriented treatment can adversely affect the patients’ ability to work or have normal social interactions, resulting in an overall reduction in quality of life. Published research data demonstrate that the establishment of a neuromuscular therapeutic occlusion provides improved mandibular and masticatory function in a large group of TMD patients with notably significant reduction or resolution of symptoms.39,152

The International College of Cranio- Mandibular Orthopedics supports the consensus among its members and thousands of neuromuscular dentists worldwide that TMD has a primary physical/functional component that is most often successfully treated with neuromuscular dental occlusion therapy, based on objective measurements.

Occlusion and Temporomandibular Disorders (TMD): Still Unsolved Question?

Journal of Dental Research, Vol. 81, No. 8, 518-519 (2002)
DOI: 10.1177/154405910208100803

Pentti Alanen Institute of Dentistry, University of Turku, Lemminkäisenkatu 2, SF 20520 Turku, Finland; pealan@utu.fi

The discussion about TMD etiology may be the longest debate in dentistry. Why does this debate still continue? I believe an answer can be found by analyzing the design of TMD studies against the principles of etiological epidemiology (Rothman and Greenland, 1998).

Both parties of the debate refer to empirical evidence. High-quality studies of occlusal adjustment in TMD patients are still too few to permit firm conclusions to be drawn (Forssell et al., 1999; Tsukiyama et al., 2001), but the use of occlusal splints seems to relieve TMD symptoms (Forssell et al., 1999). Success in therapy, however, is proof neither for nor against an etiological theory. 

Where is the Evidence Suggesting that Occlusion and TMD are not Associated?
The observation that many subjects have "occlusal abnormality" without TMD has clearly encouraged reviewers to conclude that occlusal factors have no significant etiological role (Clark, 1991; DeBoever et al., 2000). Results of experimental interference studies are also seen as strong evidence for the same conclusion (Tsukiyama et al., 2001).
It is possible, however, that the reviews by Clark (1991), Clark et al. (1999), DeBoever et al. (2000), and Tsukiyama et al. (2001) have overlooked some methodological errors in studies on TMD etiology: (1) use of data which are not suitable for etiological generalizations, (2) confusion between the concepts "sufficient cause" and "causal factor", and (3) confounders in studies of artificial interference.

There are two types of generalizations in epidemiology. Rothman and Greenland (1998) have pointed out that studies aiming at generalization to the target population require representative samples, whereas powerful tests of competing hypotheses require selected samples. The majority of the epidemiological studies of association between occlusal factors and TMD have not made this decisive distinction but have used samples representing non-selected populations. It is therefore possible that the variation has been insufficient for effective comparisons between subjects with and those without a certain trait. For a critical study design, one must select subjects with occlusion totally free from any kind of interference, and compare them with subjects with interference. If this is impractical by selection, the needed variation can be produced by adjustment (Kirveskari et al., 1992, 1998).

Sufficient Cause vs. Causal Factor
Clark’s (1991) comment that "a high percentage of patients who have a naturally occurring ‘occlusal abnormality’ do not exhibit TM disorder" discloses that a distinction between the concepts "sufficient cause" and "causal factor" has not been made. This criticism applies also to the review by DeBoever et al. (2000). The conclusion should have read: "The literature does not give strong support for the opinion that occlusion is a sufficient cause for TMD." (emphasis added)

All diseases and disorders are multifactorial in practice. The most common example in dentistry is dental caries. Not mutans streptococci alone and not a sugar-rich diet alone lead to dental decay; they are both needed in addition to a certain weakness in host resistance. Analogously, if both stress and occlusal factors are needed for TMD to develop, then occlusal factors are a causal factor but not a sufficient cause for TMD. Occlusion could be excluded as a causal factor if the absence or presence of occlusal interferences does not affect the incidence rate of TMD in longitudinal studies (Kirveskari et al., 1998).

Confounder in Artificial Interference Studies
The trials with experimental interference are considered powerful (Tsukiyama et al., 2001). Interestingly, the usually virtuous principle of including only subjects healthy at baseline can be a confounder in the present case. Healthy adult subjects have demonstrated the ability to tolerate their natural interferences. Therefore, they can also be expected to adapt to artificial interference. What would happen if the study subjects were former TMD patients? In the trial by LeBell et al. (2002), the former patients did not adapt to the artificial interference as well as did healthy controls.

To conclude, studies which have not disclosed associations between occlusion and TMD may not have fulfilled sound methodological criteria. Lack of evidence has been interpreted as evidence of lacking association. In spite of the fact that it has been much more difficult for the occlusal hypothesis to survive in the trials by Kirveskari et al. (1992 (1998) and Le Bell et al. (2002), these studies have not succeeded in finding evidence against the occlusal hypothesis. Therefore, the rejection of the occlusal hypothesis cannot be justified with the present empirical evidence.


  • Clark GT (1991). Etiologic theory and the prevention of temporomandibular disorders. Adv Dent Res 5:60–66.[Abstract/Free Full Text]
  • Clark GT, Tsukiyama Y, Baba K, Watanabe T (1999). Sixty-eight years of experimental occlusal interference studies: what have we learned? J Prosthet Dent 82:704–713.[Medline] [Order article via Infotrieve]
  • DeBoever J, Carlsson G, Klineberg I (2000). Need for occlusal therapy and prosthodontic treatment in the management of temporomandibular disorders. Part I. Occlusal interferences and occlusal adjustment. J Oral Rehabil 27:367–379.[Medline] [Order article via Infotrieve]
  • Forssell H, Kalso E, Koskela P, Vehmanen R, Puukka P, Alanen P (1999). Occlusal treatments in temporomandibular disorders: a qualitative systematic review of randomised controlled trials. Pain 83:549–560.[CrossRef][Medline] [Order article via Infotrieve]
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  • Le Bell Y, Jämsä T, Korri S, Niemi P, Alanen P (2002). The effect of artificial occlusal interferences depends on previous experience of temporomandibular disorders. Acta Odontol Scand (in press).
  • Rothman K, Greenland S (1998). Modern epidemiology. 2nd edition. Philadelphia: Lippincott–Raven, pp. 133-134.
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Tuesday, June 21, 2011

Is Occlusion A Primary Cause of TMD?

By Karen McCloy, DDS

Occlusion is the act of the teeth coming together.

A primary cause is a factor that if present will reliably initiate the pathological changes that lead to tmd in a patient that did not previously have tmd

TMD is a state of chronic pain in the tmj and the soft tissues supporting it. Chronic pain implies the presence of neural plasticity, so we are talking about a state of central sensitization involving the trigeminal nerve. There is no rule that says that tmd patients may not have similar changes in other areas of the central nervous system. Saying that someone has chronic pain does not address it's etiology, and someone with a clicking joint does not have tmd unless they have pain.

If you ask me is occlusion an important pain producing factor in patients with tmd the answer is a definite yes. In normal patients, without plastic changes, occclusal dsiharmony may be nociceptive, but that means it is not pain. Once there are neural changes it becomes pain, a form of allodynia where a nonpainful stimulus causes pain, like when you have a headache and touching your skin or brushing your hair hurts, and controlling it is key to calming down that nervous system.

But our treatment has multiple modes of action, besides occlusion.

It has a placebo effect, becasue we believe, and because of that our patients believe they will improve. Plus the decision to seek treatment also changes someones mindset and makes them more in control

Our orthotics are a form of CBT - cognitive behavioral therapy. We insert them and say lips together teeth apart, and the plastic reminds the patient what the correct oral posture is.

Orthotics provide an occlusal effect, because they provide stable and even point occlusion around the arch.

Orthotics have an orthopedic effect because the realign the mandible to the cranial base and cervical structures.

So we are back to Larry's the chicken or the egg. We only see the pain patients, and in them pain is correlated with occlusion, but that is not the same thing as causation. Our 1st study on nonpain patients showed that most of them had some form of occlusal issue, but they did not have pain. So I think something else has to happen.