Looking Forward to a New Classification System? Or Rather Not

It was tempting to write another post in the Periodontal Myths and Mystery Series – Clinical Measurements in Periodontal Disease. Guesswork whenever it comes to submarginal landmarks such as the cemento-enamel junction and bottom of the pocket; or, even worse, an assumed “tangent to the prominences of two roots” to “measure” furcation involvement. After having introduced and refined case definitions of mild, moderate and severe periodontitis for epidemiological surveys in the past decade, the same authors representing the American Academy of Periodontology and the U.S. Centers for Disease Control and Prevention had to concede, in a recent article in the Journal of Periodontology, that,

[t]hese subgroups [mild and moderate periodontitis] are not truly ordinal [sic] as the label suggests because many ‘moderate’ cases had insufficient pocket depth to qualify as ‘mild’ and we have therefore combined them and used the label ‘other‘ periodontitis,

adding even more confusion [1]. When the paper went online earlier this year, I had contacted one of the authors, Dr. Wenche Borgnakke, to explain that sentence. I had even suggested,

So, in some cases there was >= 4mm CAL but no deep pockets of >=5mm, only 4mm. So, if CAL would have been 3mm, one would have assigned it to ‘mild’, but since it was 4+mm, it had been ‘moderate,’

asking her whether I was possibly right. Unfortunately, she did not respond.

It may be the right time to inform readers of this blog that clinical instructors at Tromsø University student clinic have long identified respective problems with these case definitions while students had tried hard over the years to apply them correctly. As a matter of fact, there is usually no time to measure full-mouth attachment levels (necessary for properly assignment to respective categories), and even the OPUS system does not allow for respective recordings. Having realized the confusion, I had added some common sense descriptors in the Standard of Care, for instance, that cases with furcation involvement, infrabony lesions and/or loss of alveolar bone of more than 1/3 of the root length are usually to be classified as advanced periodontitis. Clinically, deep periodontal pockets may be associated with recession and increased tooth mobility. And that radiographs in cases of moderate periodontitis show usually loss of alveolar bone up to one third of the root length while clinically periodontal pockets and loss of clinical attachment of up to 6 mm may be found; and mild periodontitis may be related to radiologically determined loss of the lamina dura.

Now, earlier this week, a preliminary update on the 1999 Classification of Periodontal Diseases and Conditions by the AAP Task Force went online. Most interesting was the announcement that a definite update of the Classification would commence in 2017. Another surprise related to the differentiation between chronic and aggressive periodontitis. The Task Force writes,

After reviewing the original 1999 workshop proceedings and updated published literature on periodontal disease diagnosis (i.e., case definitions), epidemiology, and diagnostic markers,6-13 the Task Force affirmed the use of the terms ‘chronic periodontitis’ and ‘aggressive periodontitis’ as separate, distinct clinical entities, both presenting with sign of periodontal destruction and inflammation.

Well, the numerous problems with these “distinct entities” have been detailed in quite a large number of publications since 1999. Utterly awkward, essentialist, thinking assigning the descriptor “aggressive” to a chronic disease (yes, it is) which does not put the life of the patient at risk has been criticized as well. There had been failed attempts of omitting both terms, chronic and aggressive. And attempts to re-introduce “juvenile periodontitis” for periodontitis in adolescents. And further attempts to verify claimed diagnostic markers, microbes, genes and host response. That, as Baelum and Lopez wrote in 2003, “periodontitis is a syndrome, the clinical manifestations of which may come in all sizes,” and comes at almost any age seems to be a strange idea which does not cross the AAP Task Force’s mind.

While the 1999 Classification workshop participants tried to omit age of onset from the strong descriptors for “aggressive periodontitis”, it was quickly realized that this does not make to much sense. Now, the Task Force acknowledges the recent initiative by Albandar in the 2014 volume of Periodontology 2000 to re-introduce age and recommends “that patient age, younger than 25 years at the time of disease onset, be used  along with other signs or criteria to support a diagnosis of aggressive periodontitis.” It is stated later in the document that,

After reviewing the level of evidence on microbial and host markers, the Task Force concluded that there are no definitive biomarkers that can currently differentiate between aggressive versus chronic periodontitis or between localized versus generalized aggressive periodontitis. Hence, the clinician must base these diagnostic decisions on history, clinical, and radiographic signs.

Family history is more important here, I suppose. And what about ethnicity? Data have shown that, at least in the U.S., among black people prevalence of aggressive periodontitis is 20 times higher than among whites. It also seems to be much more prevalent in Africa. This seems to be the most convincing risk factor.

Another interesting paragraph in the Task Force’s preliminary update relates to the well-known but underreported fact that “measuring” attachment loss requires a precise location of the cemento-enamel junction, which may be lost due to abrasion or a dental restoration, hidden within the gingival sulcus or pocket, obscured by calculus, etc. pp. Amazingly, the Task Force speaks of “some guesswork” involved in attachment loss measurement. Any clinician would certainly concede that the CEJ can be clinically detected with certainty in just a minority of clinical situations in a given patient. Indeed, in numerous studies reliability of educated guesses has been reported which may even be reasonably high, but has not anything to do with a valid attachment level measurement. The Task Force writes,

Another common error occurs when gingival margin measures [sic] are charted as ‘0 mm’ when in fact the gingival margin is not right at the CEJ, resulting in attachment levels that are incorrectly charted as being equal to probing depth.

That is in fact an important concession [2]. There are hints that erroneous and misleading perceptions about probing depths equals attachment levels in the absence of recession have already found their way into the scientific literature, see, for example a recent study by my former colleagues in Kuwait.

When the Task Force makes another odd suggestion to further describe extent and severity of the disease (beyond the 30% criterion for localized versus generalized disease), for instance, “chronic periodontitis localized to maxillary molars with severe lesions on the premolars,” this may in fact lead to a more nominalistic approach demanded by several scientists for some time.

What can we expect from the upcoming new Classification Workshop in 2017? Well, as the AAP Task Force seems to stick to the distinction between aggressive and chronic periodontitis, I hope for more constructive discussions with scientists who have provided conclusive arguments against it.


[1] One reason for my letter of December 2012 to the editor of the Journal of Dental Research, Professor William Giannobile, was the conspicuous finding in the 2009-2010 continuous NHANES (published by Eke et al. in 2012) that moderate periodontitis was much more prevalent than mild periodontitis, something which may be unique within the large group of chronic noncommunicable diseases. Attachment loss was strangely defined in that report (for the first time in the long history of NHANES, by the way) by employing measurements for pocket depth and recession. The latter was to be “subtracted” from the former, not mentioning that recession had to get a minus sign when ever present (note that the term stems from Latin recessus, retreat; so, a negative measurement would rather make sense if the CEJ was located subgingivally). My letter to the editor, which can be found here, was answered in an email by the authors (who explained the procedure to me) but it was unfortunately not published in the Journal of Dental Research. I have reported on that here and here. Eke et al. nevertheless may have noticed that more moderate than mild periodontitis in a population won’t make too much sense and may have perceived need for some analytical effort. Since case definitions for mild and moderate periodontitis were not so straightforward, they reported that fact in their 2015 update of NHANES data (and actually abandoned the differentiation between mild ad moderate periodontitis). I am not sure whether many colleagues find time to trace these decisions of  our thought leaders and are willing to take them serious. There seems to be largely political motivation of the AAP (I suppose EFP politicians are motivated as well) for exaggerating prevalence, extent and severity of periodontal disease in western populations. The latest update on periodontitis prevalence in the U.S. had already to be attenuated to 45% (from slightly more than 47% which was reported also as “Half of American Adults”).

[2] In my letter [pdf] I had explicitly pointed to the conspicuous finding that, in general, prevalence and extent of attachment loss was higher than that of pocket depths which may be a hint for assuming pocket depth is attachment level whenever there was no recession. I had written,

When analyzing the Figure in the paper by Eke et al. (2012a), what immediately hits the eye is that there seems to be higher prevalence of attachment loss at different thresholds (a) than of pocket depth at respective thresholds (b) in all age groups. Such a pattern may actually be a result of how attachment loss had erroneously been redefined, most probably due to convenience. Just as a trivial example, a 4 mm probing depth without recession may be associated with either 0, 1, 2, 3, or 4 mm attachment loss, but the NHANES oral health data management program would have “instantly calculated” 4 mm.

As a matter of fact, identifying the CEJ within a pocket is a more than tricky task for any clinician. Now, at least that was recognized by the AAP Task Force. Does this render recent NHANES data unrealible? Well, it can’t be ruled out at the moment.

31 May 2015 @ 9:03 am.

Last modified May 31, 2015.


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