One of the great microbiologists among us periodontists has passed away in October this year, Dr. Walter J. Loesche. An obituary by Richard Ellen and Dennis Lopatin is being published in Journal of Dental Research and for those who have access to JDR‘s web page the respective online version may be found here. One of Dr. Loesche’s papers [pdf] (together with current Editor of Journal of Periodontology, Kenneth Kornman), which had been published just after I had received my Dr. med. dent. degree, had dealt with the possible substitution of essential growth factor vitamin K (or an analogue menadione) for Bacteroides melaninogenicus subsp. intermedius (now Prevotella intermedia or rather P. nigrescens, as has recently been shown by Gürsoy et al.) by largely increased progesterone and estradiol in gingival crevice fluid during pregnancy providing an ecological advantage for this potential periodontal pathogen and similar bacteria such as B. melaninogenicus subsp. melaninogenicus (now P. melaninogenica) in the subgingival environment. Specific and ecological plaque hypothesis elegantly united.
The short series of articles by Kornman and Loesche on pregnancy gingivitis has always fascinated me as well-conducted multidisciplinary piece of research which seemingly shed bright light on a mystery well-known for millenniums in any culture: Why do pregnant women lose teeth? And still, I like entertaining the idea that this single paper may have sparked my interest in science.
However, I doubt whether Dr. Loesche had ever used a scaler or curette other than for taking bacterial samples. While working in his lab at University of Michigan in Ann Arbor, the Department of Periodontology had gained international reputation when chaired by Professor Sigurd Ramfjord from 1963 till 1981. Ramfjord’s clinical studies laid the foundation of indications for periodontal treatment modalities, non-surgical and surgical, for in fact decades to come. But notably, Loesche challenged these indications. As Ellen and Lopatin write in their obituary,
[H]is latter metronidazole trials included a new outcome variable – ‘the reduction in the need for surgery’ – one of the earliest examples of a patientbased outcome in a periodontal therapy trial. Though his conclusions inflamed some specialists whose treatments were surgery intensive, Walter’s longitudinal trials of metronidazole were exemplary, and the notoriety was welcome. Today, the use of antimicrobial strategies is a common component of dental practice, and patients’ quality-of-life issues are routinely included in clinical research. (Emphasis added.)
The new outcome, reduction in the need for surgery, is still being considered in contemporary clinical trials. A surrogate outcome, more attachment gain, is also still of interest; see, for example, a recent post here on this blog. Since then, though, rather than but systemic metronidazole a combination of amoxicillin and metronidazole (if not contraindicated) had been advocated and many designate this broad-spectrum combination of antibiotics which, contrary to early claims, does not target specific periodontal pathogens such as Aggregatibacter actinomycetemcomitans, “van Winkelhoff ‘s cocktail” after this microbiologist and his coworkers had introduced it in 1989 in a series of cases.
It is somewhat conspicuous that proponents of adjunct antibiotic therapy, be it for the sake of parts of a millimeter more attachment gain, or reduction of treatment need for periodontal surgery, are frequently non-clinicians or not even dentists. Well-established indications for periodontal surgery such as deep infrabony lesions around in particular multi-rooted teeth, including furcation involvement, must not be expected to vanish just because adjunct antibiotics had been prescribed; nor would up to several tenths of a millimeter thick subgingival biofilm which, in certain areas, had not mechanically been disrupted due to operator’s access problems.
Almost all clinical studies of the 1970s and 1980s had unequivocally shown that properly done subgingival scaling would be able to solve most periodontal problems at suprabony periodontal lesions, in particular around easy-to-access single-rooted teeth, provided excellent oral hygiene can be maintained. Since proper conduction of subgingival scaling cannot be assessed immediately after treatment, it is reasonable to re-evaluate the periodontal situation after a healing period of, say, six weeks: In order to plan further periodontal treatment (be it nonsurgical or surgical), reinforce oral hygiene measures, restore esthetics and function; or schedule for maintenance based on periodontal risk assessment. Adjunct systemic antibiotic might in fact be an additional means in certain cases but it must not substitute an entire phase of periodontal therapy, namely what is known as the corrective, or surgical, phase. Which, if treatment went well, is commonly confined to certain areas with certain access problems. Adjunct systemic antibiotic therapy would require another round of subgingival scaling anyway since dental biofilm has to be disrupted mechanically first. Of course, the question remains, how long would additional benefits of adjunct antibiotics last? That is, how often does one have to repeat the cure, in particular when considering undesired and some serious adverse effects of systemic antibiotics?
Indeed, reduction in need for surgery may be regarded patient-centered. But what is more is definitive outcome and true endpoint, long-term tooth retention. While studies considering this particular true endpoint are cumbersome and quick results cannot be expected, they are in fact overdue.
26 December 2012 @ 1:42 pm.
Last modified December 26, 2012.