that does succeed in relieving head, neck and facial pain. The authors ignore that en- tire body of literature and histo- ry of patient success, and in- stead focus on a weak attempt to fit occlusal treatment into the same category of treatment as giving some patients antibiotics and others sugar pills to see what happens. The only valid evidence- based conclusion that Drs. Ismail, Bader and Forssell can possibly draw is that the studies mentioned were completely void of any standards and are there- fore worthless. There is no valid evidence—just a set of studies in which the exact criteria are not clear and the evidence pro- cedures are nonexistent. The problem is that these supposedly evidence-based stud- ies do not account for the ability and/or any prejudice of the oper- ator. Constructing a bite splint and adjusting the bite or equili- brating teeth is not a standard- ized, off-the-shelf process, like a bottle of pills that can be ran- domized and blinded. I do not think that anyone would argue that these two services require a very high level of technical skill. In addition, unless the exact end point is reached, the results are not conclusive. If you examine the back- grounds of the authors of stud- ies that do not validate the ef- fectiveness of bite splints and occlusal equilibration, are they practitioners who have a history of continuing education and clinical success with bite treat- ment? If they do not, and if one is truly interested in an evidence-based approach, you would have to throw out the en- tire study based on the ques- tionable ability of the operators to, in fact, achieve the required end point that they are profess- ing to study. I am all in favor of many as- pects of evidence-based den- tistry, but I am not in favor of using it as a veil to attack den- tal treatment that has been proven over 75 years by thou- sands of dentists on tens of thousands of patients. Jerry Simon, D.D.S. Stamford, Conn. 1. Forssell H, Kalso E, Koskela P, Vehmanen R, Puukka P, Alanen P. Occlusal treatments in temporomandibular disorders: a qualitative systematic review of randomized controlled trials. Pain 1999;83:549-60. Authors’ response: 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 infor- mation 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 con- trolled clinical trials provide the least biased (but not unbiased) evidence for or against a treat- ment modality. In the case of the occlusal ad- justment and temporomandibu- lar 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 bene- fit. Is it the occlusal adjustment, the caring environment provid- ed 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 com- plicated 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 contin- uing to evolve to better protect against bias, and new research projects are expected to adhere to them. In fact, research de- signs are maturing to the point that Dr. Simon’s observations are wrong concerning the inabil- ity of the evidence-based ap- proach to assess effectiveness of surgical interventions. A recent randomized, con- trolled trial of arthroscopic knee surgery, wherein a much vaunt- ed surgical procedure was test- ed against placebo, found no beneficial effect. 1 It is this level of evidence that is needed to successfully control the inher- ent bias in case studies and re- ports on success of a therapy that do not present the failed cases and do not evaluate po- tential damage to patients’ health that a treatment modali- ty may have caused. Scientific studies should report all these findings; anecdotal case reports, textbooks and continuing educa- tion courses tend to focus only on the successes. The state of knowledge on the issue of occlusion and TMD is not conclusive and is contro- versial. The differences between the systematic review we cited and Dr. Simon’s views on the ef- fectiveness of occlusal adjust- ment on TMD are an excellent illustration of these differences. However, that does not mean that dentists should not provide this treatment for the right pa- tient at the right time, if they 556 JADA, Vol. 135, May 2004 L E T T E R S Copyright ©2004 American Dental Association. All rights reserved.