We agree with Dr. Simon, and the American Dental Association’s policy states that evidence is one piece of information that should be integrated with information on patient preferences and the clinical experience of the dentist. We also agree with all his cautionary notes on the use and abuse of evidence-based dentistry.
However, we disagree with Dr. Simon regarding his implied definition of the term "evidence." In evidence-based health care, "evidence" is classified by the level of bias. Randomized controlled clinical trials provide the least biased (but not unbiased) evidence for or against a treatment modality.
In the case of the occlusal adjustment and temporomandibular disorders, we agree with Dr. Simon that many patients are treated with these appliances and do show benefits. However, neither we nor Dr. Simon can discern the source of the benefit. Is it the occlusal adjustment, the caring environment provided by an experienced dentist, or characteristics of patients? What are the outcomes without providing occlusal adjustments? What are the harms associated with this treatment?
Like clinical practice, clinical research is a difficult and complicated venture. The "lack of standards" that Dr. Simon refers to is a problem in all fields of clinical research, as well as in clinical practice. However, standards are continuing to evolve to better protect against bias, and new research projects are expected to adhere to them. In fact, research designs are maturing to the point that Dr. Simon’s observations are wrong concerning the inability of the evidence-based approach to assess effectiveness of surgical interventions.
A recent randomized, controlled trial of arthroscopic knee surgery, wherein a much vaunted surgical procedure was tested against placebo, found no beneficial effect.1 It is this level of evidence that is needed to successfully control the inherent bias in case studies and reports on success of a therapy that do not present the failed cases and do not evaluate potential damage to patients’ health that a treatment modality may have caused. Scientific studies should report all these findings; anecdotal case reports, textbooks and continuing education courses tend to focus only on the successes.
The state of knowledge on the issue of occlusion and TMD is not conclusive and is controversial. The differences between the systematic review we cited and Dr. Simon’s views on the effectiveness of occlusal adjustment on TMD are an excellent illustration of these differences. However, that does not mean that dentists should not provide this treatment for the right patient at the right time, if they have the skills and experience to do so. In the absence of good research-based evidence, we need to convene a workshop to reach consensus on when, how and what bite splints are to be recommended. However, in order to do so, we need to shed our biases and beliefs that clinical practice is only an art. When we go to our dentists, we wish to be treated by the best science and art available.
The American Dental Association’s policy on evidence-based dentistry incorporates dentists’ clinical experiences and patients’ preferences with scientific evidence to make the best possible treatment decisions. This approach is the right one for dentistry and all health-care fields. The lack of unbiased evidence does not mean there is no evidence, or that a treatment is not effective. We need to document, in an unbiased manner, the impact of any treatment modality. Hence, we concur with Dr. Simon that we need clinical research that follows current standards to resolve his concerns.
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