Evidence-Based Dentistry: How Good is the Evidence?

The goal of dental education is to help dentists offer patients appropriate treatment options to address the clinical concerns unique to each person. To determine what treatment options may be most appropriate, dentists use PubMed or Google Scholar to search for published papers for guidance and insight into what might be best for the patient.

The assumption is if a paper is published in a peer-reviewed journal, the information in the paper has been examined by expert reviewers and the information is deemed acceptable in the scientific community. The real question is how reliable is the information in the published literature?

The sobering reality is the literature we depend on may be flawed. The Lancet is the world's leading independent general medical journal. The journal's coverage is international in focus and extends to all aspects of human health.

The Lancet publishes the original primary research and review articles of the highest standard. It's stringently edited and peer-reviewed to ensure the scientific merit and clinical relevance of its diverse content. Drawing on an international network of advisers and contributors, The Lancet meets the needs of physicians by adding to their clinical knowledge and alerting them to current issues affecting the practice of medicine worldwide.

In 2015, Dr. Richard Horton, The Lancet's editor-in-chief, wrote an essay outlining the issues seen today when trying to practice evidence-based dentistry. He writes:

“The case against science is straightforward: much of the scientific literature, perhaps half, may simply be untrue. Affected by studies with small sample sizes, tiny effect, invalid exploratory analyses, and flagrant conflicts of interest, together with an obsession for pursuing fashionable trends of dubious importance, science has taken a turn toward darkness. As one participant put it, 'poor methods get results.'

“The Academy of Medical Sciences, Medical Research Council and Biotechnology and Biological Sciences Research Council have now put their reputation weight behind an investigation into these questionable research practices. The apparent endemicity of bad research behavior is alarming. In their quest to tell a compelling story, scientists too often sculpt data to fit their preferred theory of the world. Or they retrofit hypotheses to fit their data.

“Journal editors deserve their fair share of criticism too. We aid and abet the worst behaviors. Our acquiescence to the impact factor fuels an unhealthy competition to win a place in the select few journals. Our love of 'significance' pollutes the literature with many a statistical fairy tale. We reject important confirmations.

“Journals are not the only miscreants. Universities are in a perpetual struggle for money and talent, endpoints that foster reductive metrics, such as high-impact publication. National assessment procedures incentivize bad practices. And individual scientists, including their most senior leaders, do little to alter a research culture that occasionally veers close to misconduct.”

Dr. Horton continued by asking, “Can bad scientific practices can be fixed?”

“Part of the problem,” he wrote, “is that no one is incentivised to be right. Instead, scientists are incentivized to be productive and innovative... Instead of changing incentives, perhaps one could remove incentives altogether. Or insist on replicability statements in grant applications and research papers. Or emphasize collaboration, not competition. Or insist on preregistration of protocols. Or reward better pre and post publication peer review. Or improve research training and mentorship.”

Occlusion and TMD literature

Since 2012, I've had the good fortune of writing the review of literature in the disciplines of occlusion and TMD for the American Academy of Restorative Dentistry. This review is published annually in The Journal of Prosthetic Dentistry. I have read the occlusion and TMD literature extensively and Dr. Horton's comments accurately reflect the quality of the literature in the field of occlusion and TMD.

Many of the concepts taught in occlusion and TMD are unsupported in the literature and are in direct conflict with literature in peer-reviewed journals. The reality is not everything in the literature is correct and not everything correct is in the literature.

The challenge is for each practitioner to have a sound clinical thought process balanced with a good understanding of the literature.

Jim McKee, D.D.S., is a member of Spear Resident Faculty.

References

Horton R. Offline: What is medicine's 5 sigma? The Lancet. 2015;385(9976):1380.