My coauthors and I thank Drs. Hayes, Peterson and Ostreicher for their interest in our article. Their letters express concern regarding the findings of our systematic review on the relationship between periodontal health and orthodontic therapy.
Dr. Peterson suggests that the systematic review regarding orthodontic therapy and periodontal health is an example of useless research and that the efforts would be better spent on real research projects and real patients. This systematic review was commissioned and funded by the ADA Foundation. This organization identified the most pressing questions to be addressed with systematic reviews based on a survey of more than 5,000 general practitioners and specialists.
An unbiased review of all available studies is the most objective way to find ‘the truth,’ even if the results are not what we thought they should be or what we would have liked to see.
The ADA also organized a symposium to identify these pressing questions, at which professional organizations, insurance companies and government agencies were present. On the basis of this work, four topics were selected and requests for proposals were publicized. The ADA Council on Scientific Affairs selected the most meritorious applications.
Even if one agrees with Dr. Peterson’s viewpoint that the identified evidence is arcane, an important goal was nonetheless achieved: there is an absence of controlled evidence to support the common claim that orthodontic therapy provides periodontal benefits.
We agree that the quality of the studies included in the review was not as high as one may have liked, a weakness we addressed thoroughly in our discussion. However, using strict inclusion criteria, we have included all available studies on this topic, which reported on more than 1,670 patients on four continents. This needs to be compared with the "evidence" that convinced Dr. Hayes that orthodontics can help with periodontal issues (a pilot study, which is not mentioned in his cited reference1).
Dr. Hayes’ comment that the answer to some questions can be intuitive ("Ask a dentist about crowded incisors and plaque accumulation") indicates a lack of understanding of the question our systematic review addressed: the relationship between periodontal health and orthodontic therapy. This is different from the relationship between crowding and plaque accumulation. Dr. Ostreicher also fails to make this distinction and bases his statement that "frequently orthodontic treatment is of great benefit to periodontal health" on a study that reports worse periodontal health in malpositioned and crowded incisors.2 The other four references he cites also relate malocclusions to periodontal health and do not evaluate the effects of orthodontic treatment. While it makes sense to "assume" that straightening teeth would have to improve periodontal conditions, this does not provide evidence; it only provides biological plausibility, the lowest level of evidence.
We disagree with Dr. Ostreicher that we failed to disclose the entire truth. We believe an unbiased review of all available studies is the most objective way to find "the truth," even if the results are not what we thought they should be or what we would have liked to see. Interestingly, another recent review reported the same results as we did.3 If the need for scientific evidence regarding the positive periodontal effects of orthodontic therapy is important, then we hope that the profession will follow Dr. Peterson’s suggestion and initiate new research with the confidence that the existing evidence is inadequate.
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