In 1970, four-hundred-and-eighty male employees of tea plantations in Sri Lanka had been examined for the first time by western periodontists in order to start a longitudinal study of the natural history of periodontitis. It was assumed that the cohort, who supposedly lived their entire life on the plantation, had been unaffected by any treatment of periodontitis and professionally recommended or supervised oral hygiene practices.
Several papers had been published already by the mid 1980s. The study went on, and after lots of turmoil and civil war in Sri Lanka, even the tsunami of 2004, an attempt was made in 2010 to contact all participants of 1970 (Ramseier et al. 2017). Seventy-five were still available.
Ramseier et al. (2017) emphasize, in the introduction to their paper that,
[h]ypothetically, studies following subjects over a number of decades may give better insight into undisturbed disease progression, particularly between subjects showing different disease susceptibility. In this context, the untreated Sri Lankan tea labourers provided a unique opportunity to further study periodontal disease progression in humans unaffected by professional or individual oral care. (Emphasis added.)
Hypothetically. In reality, it’s unethical (see below). At least, after new insights into the disease progression had been gained in 1986, participants (human beings after all) should have been offered thorough information about causal agents (then, without doubt, well-known), preventive measures (well established) and, yes, proper treatment.
It is reported that the study by Ramseier et al. (2017) was approved by the local dental school (apparently none of its administration qualified as co-author) and the Institutional Review Board of the University of Hong Kong SAR [sic]. No governmental ethical committee was consulted. As regards the participants (who were between 55 and 70 years of age when re-examined; note that Sri Lankans had, in 2010, a mean life expectancy of 77.9 years at birth), they were, in 2010,
informed in their native language (Tamil) by a medical doctor about the details of the study. They then gave consent by finger printing due to illiteracy.
In 2010, authors report that, fortunately,
[a]ccording to the Medical officer and the administration of the Estates [Dunsinane, Harrow and Sheen in Pundaloya], the subjects’ diet improved over the period of 40 years, and the salaries of the subjects increased continuously. Yet, the older generation analysed in this study did not communicate with the outside world and the majority remained illiterate.
On the other hand, subject interviews confirmed
persistent lack of professional preventive oral health care or cleaning devices other than occasional use of bare fingers and ashes.
In September 1992, I had been invited by the Swiss Society of Periodontology (SSP) to attend the annual meeting in Lugano. Ealier that year, I had submitted a manuscript for the Hans-R. Mühlemann Research Prize which was part of my PhD thesis. I had been informed in summer that I had been selected for the competition, one among four or five finalists, including Peter Galgut and Peter Schüpbach who I considered serious competitors. The jury consisted of (former awardees) Andrea Mombelli and Thomas Hassell, as well as Max Listgarten. Late Hubert Schroeder presented parts of his recent work, a monolithic, roughly 60 printed pages long review article in the International Reviews in Cytology on biological problems of regenerative cementogenesis. Schüpbach’s presentation was about structural and ultrastructural features of healing events between regenerated periodontal ligament and root surface after experimental periodontal disease in dogs. I presented 2-yr data of comprehensive treatment in patients with different types of periodontitis all infected by A. actinomycetemcomitans.
I won the award, and late Hans Mühlemann (he passed in 1997) cordially congratulated me on stage emphasizing the many years of hard work for eventually yielding this tiny piece of research. The Mühlemann Prize was, at that time, one of a few international awards for young periodontists (the other important in Europe was the Jens Waerhaug Prize of the Scandinavian Society of Periodontology) and I still take much pride for actually winning it. What I did not know was that the award had become political that year. There was outrage among the people from Zurich when it became clear that I had won the prize and not Schüpbach. Bernard Guggenheim, co-author of Schüpbach’s paper, later announced that he would leave the SSP in protest. I got this information years later from Klaus Lang, who was cagey not to attended this particular annual meeting but had certainly made sure that his right-hand man Mombelli was in the jury probably with the purpose to prevent any triumph for the people from Zurich. I really felt ashamed.
I vividly remember a particular oral examination in Kuwait when the external examiner, a professor from Sweden, had not shown and I and then chairman of the surgical department, Tryggve Lie from Norway, had to quiz the bright candidate by ourself. It was quite an inspired exam, much about figuring out whether deeper understanding of underlying biological mechanisms of pathogenesis and healing of periodontal disease was present or not .
When we discussed periodontal regeneration, I asked the candidate at one point whether she could recall the cover of the new edition (the fourth, of 2003) of what is still referred to as Lindhe’s textbook. No, she said but we had a copy at hand. It had actually puzzled me for some time, in particular the authors had not mentioned their source. It apparently showed a histological section of an implant which was in touch with two remaining roots. On page 658, in chapter 28 on Regenerative Periodontal Therapy, the image appears again. The legend tells,
” Fig. 28-13. Microphotograph of a titanium implant placed in contact with retained root tips (a). A distinct cementum layer (arrows) and periodontal ligament (PL) in continuity with that on the roots (R) is visible on the implant surface.”
The November 2012 EFP and AAP workshop on systemic health and how it is affected by periodontal disease has resulted in the joint publication of a couple of valuable systematic reviews in both Journal of Clinical Periodontology and Journal of Periodontology. I have expressed my strong opinion here on this blog that, in essence, there was not so much new or surprising. That there is strong evidence for minor effects of periodontitis on, say, cardiovascular disease and that diabetes mellitus is affected by periodontal disease while it is a risk factor for gum disease itself has been known for decades. That, what organizers had claimed, there is now a need for intervention studies to show that the risk for cardiovascular events may be reduced, has been questioned on this blog and elsewhere.
I have criticized the workshop’s Manifesto, a press release which reduced the somewhat difficult to digest information to a message for the public (and I include here in particular most of the dental profession whose members may not be able or willing to read through the pages of documents, be it but systematic reviews let alone the original cohort studies). I have also suggested a brief example (based on a gut feeling of a possible risk ratio) in which the most relevant ethical problem of not treating huge cohorts for periodontal disease was mentioned while probably a great number of patients with periodontitis had to be treated successfully (number needed to treat) in order to prevent a single cardiovascular event (if the effect was causal) which renders the whole exercise probably irrelevant.