COMMENTARY Many Questions Are Unanswerable; Many Answers Are Questionable Anthony DiAngelis, DMD, MPH Some 20 years ago, the above title presented itself to me in the form of a message tucked in a fortune cookie. It could not have appeared at a more propitious moment, as I was struggling to prepare a presentation for a dental society meeting. The struggle was not an issue of content or desire, but rather one of challenging myself to present a subject that I had often presented in a manner that rekindled a level of enthusiasm so necessary for holding an audience’s interest. The subject was HIV, AIDS, and the profession’s responsibility for providing dental care to infected patients while protecting patients and providers alike. For those who recall that time, we were short on science, long on fear, and awash in moral, ethical, and legal dilemmas. To make a long story short, I gave an hourlong lecture using but one slide: that of the fortune cookie and its profound message. As the years passed, the message has retained both its currency and relevance to the inexorable evolution of clinical practice and dental research. At the clinical level, the focus now is clearly on cosmetics, implants, digital technology, and evidence-based practice. At the research level, inflammation is the driver—more specifically, the relationship between oral infections (primarily periodontal disease), their mediated inflammatory response, and their subsequent relation to systemic diseases such as cardiovascular disease, peripheral artery disease, stroke, diabetes, pancreatic cancer, and adverse birth outcomes. The literature of the past 10þ years has suggested an association between periodontal disease (PD) and preterm birth (PTB), preterm low birth weight, low birth weight (LBW), pre-eclampsia, miscarriage or stillbirth, and intrauterine growth restriction. Given that PTB in the United States costs $26 billion annually and that children born prematurely carry with them into adulthood higher rates of respiratory, cardiovascular, and neurodevelopmental problems, and given the fact that PD is both preventable and treatable in a cost-effective manner, confirmation of PD as an independent risk factor for adverse birth outcomes would be highly desirable from a public health perspective. To date, the preponderance of literature consists of case– control, cohort, and cross-sectional studies with but a handful of interventional studies. Although epidemiological
studies favor an association by a margin of two to one, it is instructive to examine the limitations of this literature more closely. First, one must agree that the etiology of preterm birth is multifactorial, complex, and associated with multiple confounding variables. Second, it is generally accepted that infections are associated with 30% to 50% of all premature deliveries. This latter factor gives biological plausibility to periodontal infection as a possible independent risk factor for preterm birth and other aforementioned adverse birth outcomes. The studies to date, however, are significantly hampered by differing definitions and clinical measures of periodontal disease and adverse birth outcomes, as well as widely varying treatment protocols. Many studies suffer from lack of sufficient numbers of subjects and controls, others fail to control for confounding variables recognized as risks factors for PTB and other adverse birth outcomes. Still others reflect results limited to specific populations. For example, most European, Asian, and Canadian studies show no association between PD and adverse birth outcomes, whereas many studies from the United States and Latin America demonstrate varying degrees of association. Randomized, controlled interventional studies represent the gold standard when determining causality. Additionally, proving causality and treatment efficacy may or may not occur in tandem. For example, there is a strong association between bacterial vaginosis, an infection of the lower genital tract, and PTB; however, treatment with antibiotics in controlled clinical trials failed to reduce the risk of PTB from bacterial vaginosis.1 Reported interventional studies, of which there are but a few, demonstrate mixed results. The largest (N = 823) multicenter randomized controlled interventional study to date, the Obstetrics and Periodontal Treatment trial showed no association between PD treatment and reduction in rates of PTB, LBW, fetal growth restriction, or preeclampsia. However, it did show a trend of earlier preterm births (ie, spontaneous abortion and stillbirths) in the control group compared with the treatment group. Additionally and surprisingly, the study demonstrated that treatment of periodontitis in pregnant women is both safe and effective in improving periodontal health.2
For some, the results of this study are either vexing or disappointing. In 2004, the American Association of Periodontists (www.perio.org) issued a statement recommending that pregnant women or women planning to become pregnant should undergo periodontal examinations and receive preventive or therapeutic services to reduce the risk of delivering preterm or LBW babies. The evidence is now somewhat less clear regarding the aforementioned advice. Much as ‘‘a single sparrow doth not a spring make,’’ the Obstetrics and Periodontal Treatment trial is the largest multicenter study to examine this association in a diverse population. For the moment, we can neither determine causality nor conclude that treatment of periodontal disease during pregnancy will reduce adverse birth outcomes despite strong evidence of association between PD and increased risk of PTB and LBW primarily in economically disadvantaged women. Results, however, go where results go, not necessarily where we believe they should go. We are beyond relying on further observational studies; larger and methodologically rigorous multicenter interventional trials are required to answer a multitude of questions regarding this association. Several such studies are now underway. Periodontal infection and its potential for systemic inflammatory effects
might well play a role, or it may just be along for the ride. It may, as suggested in a recent editorial, ‘‘share a common etiological mechanism such as a genetic predisposition for a hyperinflammatory response.’’1 It is well to remember George Tukey’s admonition that ‘‘an approximate answer to the right question is better than a precise answer to the wrong question.’’ We are still sorting out how best to ask and answer the right questions; fortunately, both dentistry and medicine have exceptional scientists researching them. Anthony DiAngelis, DMD, MPH Chief of Dentistry, Hennepin County Medical Center, Professor, University of Minnesota School of Dentistry
References 1. Stamillo DM, Chang JJ, Macone GA: Periodontal disease and preterm birth: do the data have enough teeth to recommend screening and preventive treatment? Am J Obstet Gynecol 296:93-94, 2007. 2. Michalowicz BS, Hodges JS, DiAngelis AJ, et al: Treatment of periodontal disease and the risk of preterm birth. N Engl J Med 355:1885-1894, 2006.
Dental professionalism Background.—Admiral Hyman Rickover stated that professional conduct was based on the obligation to reject direction by lay persons in performing professional duties and the obligation to use professional knowledge and skills only to benefit clients (Box 1). Current practice does not adhere to these 2 obligations. Concerns.—Financial concerns, sometimes expressed by patients, and other outside influences appear to be creeping into the relationship between professional and patient. Decisions are being dictated by lay concerns, not purely professional standards. Treatment recommendations may be based on the patient’s coverage under a dental plan rather than solely on the patient’s perceived benefit. Analysis.—It is up to professionals to promote both innovation and excellence in their practices. Rather than promote mediocrity, professionals must determine the standard of care and create value for services they render. It is important to concentrate on the main thing. Although that main thing may differ among individual practitioners, the goal should be to determine what it is and then follow through until the main thing is accomplished. Doing what is
Professionalism.—To practice a profession, one must have acquired mastery of an academic discipline, as well as a technique for applying this special knowledge to the problems of every life. A profession is, therefore, intellectual in content, practical in application. Professional conduct—professional behavior— is based on two rules. First is the obligation to reject lay direction in the performance of professional work. That is the duty to maintain professional independence. Service ceases to be professional if it has in any way been dictated by the client or employer. Professional independence is not a special privilege, but rather an inner necessity for the true professional man and a safeguard for his employers and the general public. Without it, one negates everything that makes a him a professional person and becomes at best a routine technician or hired hand, at worst, a hack. The second such rule is the obligation to use professional knowledge and techniques solely for the benefit of clients. —Adm. Hyman G. Rickover, U.S. Navy, 1900-1986 ‘ Father of the nuclear navy’’ (Courtesy of Machnowski TJ: An erosion of trust? CDS Review Dec 2006, p 6.)