The Literature That Shaped Modern Periodontology (III)

While all of us eagerly await the promised monthly comments on  eleven themes which have been identified by J Perio’s Editor-in-Chief Dr. Kenneth S. Kornman and colleagues Drs. Paul B. Robertson and Ray C. Williams, your humble blogger will just go ahead sharing with my readers own thoughts which came to my mind when reading the extensive reading list on the Literature That Shaped Modern Periodontology. As the responsible teacher of Perio at The Arctic University of Norway, I feel obliged to put the list somewhat into perspective, in particular since Kornman et al. focus on just highly cited papers (which may frequently represent mainstream) and further consensus papers of importance as suggested by various U.S. postgraduate program directors. And especially as a highly esteemed colleague representing another subject here has put the list on fronter as if it was the best since the invention of chocolate ice cream. Since, for undergraduates, the list inevitably will causes if anything but shock and awe, there is apparent need for some moderation.

4. Periodontitis and Other Systemic Diseases Interact – in Both Directions

First, I want to make sure that I am no heretic. Interaction between periodontal disease and systemic health is, of course, an old story which has only been revived about 25 years ago, undoubtedly to some success for larger parts of our profession. For instance, even before 1990 or so it was well known that diabetes mellitus is associated with considerable periodontal morbidity. On the other hand, when having a look at clinical studies back in the 1970s and 1980s, one frequently reads that periodontitis patients “otherwise healthy” had been enrolled in the trials. After having realized in the meantime that periodontitis is associated with whatever chronic disease or condition is considered, be it lung cancer at one extreme or erectile dysfunction at the other, one can only come to the conclusion that the topic, which gets so much attention nowadays, had in the old days completely been ignored (as had been the effect of smoking on periodontal health). That “bad dentistry” may have, in certain cases, even fatal consequences is, on the other hand, not a new idea but had led, in particular in the United States and later, for instance, in Germany to what was sometimes vilified “Gnathology”, which should not be mistaken just as “occlusal ideology” but rather striving for proper biological function of fixed and removable restorations.

Well, the list under the above theme by Kornman et al. consists of four highly cited papers on by and large cardiovascular issues, three papers on diabetes mellitus, one on preterm low birth weight; and one consensus report on the general issue. Since the papers, which have been chosen by Kornman et al., are those with remarkable numbers of quotation, controversial papers are missing. I have written, in a previous post, on a heated discussion by two groups of scientists who had attempted data mining on NHANES I and follow-up surveys in order to prove or disprove that periodontitis was associated with cardio or cerebrovascular diseases. Resulting papers had been published in highly ranked medical journals but it appeared that one group was only willing to recognize a positive finding of an association, but heavily criticized methodological issues in the data when it came to the negative finding of no association. You may find links to the controversial papers here. Both papers are highly cited as well, Hujoel et al. (2000) is quoted, according to Google Scholar, 402 times; Wu et al. (2000) is quoted 385 times (accessed 2 February 2014).

The highly cited papers in the list are, with one possible exception considering surrogate markers of cardiovascular disease in a periodontal intervention trial, cross-sectional or longitudinal observational studies which cannot prove causality. In the meantime, certain very large intervention studies have been conducted on possible effects of periodontal therapy on true outcomes, glycated hemoglobin in diabetes mellitus and low birth weight, which should have sobered the discussion. (In fact respective results have rather alerted the profession and claims have been made as to possibly poor quality of periodontal therapy provided to the test group participants). The paper by Michalowicz et al. (2006) [pdf] on the effect of periodontal therapy on the risk of preterm birth has, after all, been quoted 347 times, that by Offenbacher et al. (2009) [pdf], who had attempted to challenge Michalowicz et al. but ended up with similar resuts, was quoted 100 times after just 5 years. That periodontal therapy does not lead to relevant decreases of HbA1c in diabetics as observed in a recent huge intervention study by Engebretson et al. (2013) [pdf]  has led to considerable turmoil among AAP officers. I have reported on that here.

So, by and large, the list may mislead undergraduates and general practitioners as well as it features old papers which have been shown to have trumpeted premature results which were never convincing in the long run; and ultimately, if not outrightly refuted, have largely been put into perspective.

2 February 2014 @ 10:20 am.

Last modified February 3, 2014.

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