In a recent editorial in Quintessence’s Oral Health & Preventive Dentistry, Kocher & Holtfreter (2017) had asked, “Is the prevalence of periodontitis declining or not?” and had referred to the “landmark paper” by Kassebaum et al. (2014) in which the “global burden of severe periodontitis” was estimated at about 11%, or 743 million. The first Kassebaum paper had sparked considerable interest claiming that severe periodontitis was, in 2010, “the sixth most prevalent condition in the world.”
- Static prevalence and incidence rate estimates in 1990 and 2010 by Kassebaum et al. (2014)
As with all Global Burden of Disease (GBD) reports, in the paper by Kassebaum et al. (2014) data of a large number of very heterogenous epidemiological studies was used from all over the world and metaregression done. Published studies were supplemented with hand searches of reference lists of relevant publications and textbooks, government and international health organizations web pages, even conference reports, theses, government reports and unpublished survey data (gray literature).
Based on 65 prevalence studies, but only 2 (or 3; reported numbers differ in the flow chart describing selection of studies, and text) incidence studies as well as 5 (or 6) mortality (sic!) studies, Kassebaum et al. (2014) were able to estimate prevalence patterns in 1990 and 2010 (which strangely appear to be static) and made the strong claim (based on 2 or 3 studies) that incidence of severe periodontitis peaks at about age 38 years with more than 2000 new cases per year among 100,000.
Garbage in, garbage out?
A few words on heterogeneity of data. Kassebaum et al. (2014) had “identified 3 comparable quantitative indicators” of severe periodontitis, i.e. CPITN score of 4, attachment loss of >6 mm, and pocket depth of >5 mm. Taken as a singular observation, none of these indicators, per se, would actually point to “severe periodontitis” which would be considered a much more serious disease. Extent of the disease is of importance when describing periodontal disease, something which periodontists are or should be aware of. Mixing partial and full-mouth probing in the various studies considered is another caveat (or flaw) in Kassebaum’s analysis. One might instantly think, garbage in – garbage out.
Earlier this year, delegates of the European Federation of Periodontology (EFP) and the International Diabetes Federation (IDF) had met in Madrid for a joint workshop on an update of the Perio-Diabetes link. I had reported on the event and some key findings, quickly posted on the EFP web page, here.
Already on and after 24 August 2017, a Consensus Report by the two organizations was prematurely published, and quickly (temporarily) withdrawn, in the EFP’s Journal of Clinical Periodontology and the IDF’s Diabetes Research and Clinical Practice. I had managed to get a print-out of the not-yet edited (and later withdrawn) draft version published on the JCP Accepted Articles page and had noticed that most of the evidence presented was derived of yet-to-be published review articles based on the workshop proceedings.
The final version of the Consensus Report (Sanz et al. 2017, Early View Articles), including guidelines for patients and health professionals dealing with patients suffering from diabetes and periodontal disease, went online this week, but still references to review papers presented on the occasion of the workshop have a 2017 assignment and are not paginated which may make it more difficult for scientists and clinicians outside periodontology or dentistry to locate the final papers.
To be clear, when it comes to keeping our medical collegues, and in particular diabetologists, interested in the very long-known link between periodontitis and metabolic diseases, proving beneficial effects of periodontal treatment on diabetic control is crucial. All was fine as long as numerous published, small-scale, mostly single-center, and often poorly executed, trials apparently showed that thorough subgingival scaling in patients with both periodontitis and diabetes led to an about 0.4% reduction of glycated hemoglobin (HbA1c), at least after three or four months. As that would in effect spare an additional antidiabetic drug, diabetologists stayed interested. Although results in a few trials indicated that the effect was not long-lasting, i.e., no longer discernable after, say, six months.
Another edition of a joint EFP/AAP workshop has just closed in Chicago, and periodontal scientists and teachers all over the world are eagerly awaiting the proceedings to be published in our core scientific journals, the Journal of Periodontology and the Journal of Clinical Periodontology. The workshop’s agenda had been announced on the EFP website on Thursday this week.
Hallmarks of the previous Classification of Periodontal Diseases and Conditions of 1999 had included a thorough classification of gingival diseases and renaming, once more, juvenile/early-onset periodontitis as “aggressive”, and the more common “adult” form of periodontitis as “chronic”. Many scientists, in particular epidemiologists had considered the latter achievement as highly problematic. Not only that disease definitions included some laboratory tests not available to the common practitioner; progression rates were to be assessed as well. Both is utterly difficult, if impossible, in epidemiological research.
And, as assumed microbiological cause and pathogenesis of either chronic or aggressive periodontitis do not differ fundamentally, does a differentiation even make sense? What comes to one’s mind is, of course, diabetes where types I and II have different causation and can easily be differentiated despite common clinical signs and symptoms.
The above is the conclusion of a recent retrospective evaluation of root-resected molars during a time-span of 30 years in a private practice. I would like to draw attention in particular to the last part of the sentence which is of utmost importance. I shall explain below what I think is necessary when reporting research findings in an honest way.
When has root resection been reported first?
Root resection, or amputation, is an old story. According to common wisdom, it had been Dr. John N. Farrar from Brooklyn, NY, who had reported first on so-called “radical and heroic treatment” of alveolar abscesses by amputation of roots of teeth , “in order to enable nature to have a better chance for cure.” Dr. Farrar correctly stated that, “if an entire tooth should be extracted from a diseased socket, the treatment might be termed highly radical.” He considered that such a treatment might not only unwise and unnecessary but “absolutely wrong and unscientific [sic].”
It is amazing that, some 130 years ago, reporting couple of cases was considered “science”. The times they are a changin’. Maybe in 100 years our current approach to what is still regarded scholarship and science will be ridiculed as well.
What can be achieved
Root resection or hemisection of furcation-involved molars are still common treatment options based on more rigorous research in the past 45 years. There may be also other indications, endodontic and iatrogenic. Implant dentistry is of course an interesting alternative, and a not so recent case series of patients attending a single private practice by Fugazzotto (2001) from Milton, MA, had shown comparable results regarding successful treatment of either root resection of molars (n=701) or placing implants in molar locations (n=1472) after 15 and more years and 13 years, respectively. Indeed remarkable results, namely success rates of 96.8% for root resected molars and 97% for implants.
Shortly before recent updates of the Global Burden of Disease (GBD) studies (supported by the Bill & Melinda Gates Foundation) sparked considerable attention in the news, dubious metrics like disability-adjusted life years (DALY) and years lived with disability (YLD) had been calculated for a number of oral diseases and conditions such as (severe) periodontitis. These metrics are basically derived from estimates of incidence (and, recently also, prevalence) of the disease, and a disability weighing factor; but interpretation must be regarded spurious. One may intuitively ask the important question, cui bono?
In its recent update on the global burden of oral diseases, Kassebaum et al. (2017) claimed 538 million cases of severe periodontitis worldwide in 2015, 231 million more than estimated for 1990. Disability-adjusted life years (DALY) for severe periodontitis were calculated at 3.518 million. In a recent white paper by Tonetti et al. (2017), this latter figure was emphasized, “3.5 million years lived with disability.” These authors further their arguments about the “Impact of global burden of periodontal diseases on health, nutrition and wellbeing of mankind” by adding estimates provided by Listl et al. (2015) on the global cost of lost productivity from severe periodontitis alone (54 billion USD/yr). Productivity loss values 1 DALY as 1 yr of per capita gross domestic product.