Richard Niederman DMD, MA
An association could not be verified between TMD and orthodontic treatment or malocclusion.
Nine trials could not identify a cause-effect relationship between malocclusion or orthodontic treatment and TMD.
a) Is there a cause-effect relationship between orthodontic treatment and TMD? b) Is there an association between different types of malocclusion and TMD?
The authors reviewed human clinical trials identified in MEDLINE and Cochrane Central between 1966 and 2005, published in English or Scandinavian languages. Of the 58 publications identified: 28 were excluded as being irrelevant; 21 were described as having limited evidence; and 9 were described as having moderately strong evidence. No randomized controlled trials were identified.
The 9 trials (cohort, case-control and case series), consistently, could not identify a relationship between malocclusion or orthodontic treatment and TMD.
The authors concluded that an association could not be verified between malocclusion and development of TMD.
Source of Funding:
Swedish Council on Technology Assessment in Health Care.
Importance and Context:
Moderate-severe or severe TMD is estimated to affect 7% of the U.S. population.1 If there is a cause-effect relationship between malocclusion and TMD, then addressing the underlying cause (i.e.: malocclusion) may alleviate the effect (TMD).
Strengths and Weaknesses of the Systematic Review:
This review implemented accepted and established approaches for searching and evaluating the reported trials. Because of substantial differences in the types of clinical trials, the authors qualitatively, not quantitatively, summarized the results.
Strengths and Weaknesses of the Evidence:
Because cohort, case-control and case series trials were identified, but not randomized controlled trials, the strength of the current best evidence is limited. However, a consistent outcome was found among all the trials.
Implications for Dental Practice:
This review provides no support for an association between malocclusion and TMD. Similarly, there is no evidence that orthodontic treatment may cause TMD. This review, therefore, suggests that clinicians exercise caution when prescribing orthodontics or reconstruction to treat TMD. In addition, prospective diagnostic trials have found only a modest relationship between occlusion and TMD. 2, 3
1. Lipton JA, Ship JA, Larach-Robinson D. Estimated prevalence and distribution of reported orofacial pain in the United States. J Am Dent Assoc. 1993; 124:115-21.
2. Landi N, Manfredini D, Tognini F, Romagnoli M, Bosco M. Quantification of the relative risk of multiple occlusal variables for muscle disorders of the stomatognathic system. J Prosthet Dent. 2004; 92:190-5.
3. Schmitter M, Balke Z, Hassel A, Ohlmann B, Rammelsberg P. The prevalence of myofascial pain and its association with occlusal factors in a threshold country non-patient population. Clin Oral Investig. 2007;11:277-81.