Update on How to Measure Attachment Loss

As I have reported in my previous post, in the current controversy with authors of a recent update of prevalence of periodontal disease in the U.S. as observed in the 2009-2010 NHANES, the editor of Journal of Dental Research, Professor W. Giannobile, had expressed regrets that he has declined to publish either an Erratum or my letter [pdf]. According to Dr. Giannobile, authors had conceded that

“[T]he algorithm used to calculate attachment loss (AL) in NHANES can intuitively be misunderstood because it is stated that subtraction measures of gingival recession from measures of pocket depth PD (and not added as one would expect intuitively). However, mathematically this is correct. The recession is called out as a negative number by the examiner and is subtracted from the PD i.e., PD – (-recession) = PD + recession (if the FGM is below the CEJ) which adds up to the sum of the recession plus the PD. If the FGM is above the CEJ, then it is the direct sum of the recession (which is positive) and PD. Thus in NHANES, AL is calculated from three anatomical points versus a direct measure from the CEJ to the bottom of the pocket as may be done clinically (Clinical attachment loss). There is a long history behind why NCHS [National Center of Health Statistics] has used this approach, however this is how AL has been determined for all previous NHANES including NHANES III (the dataset used by Albandar 1999), NHANES 1999-2004 and NHANES 2009 – 2010.”

Honestly, I had not expected anything else. The authors actually claim that they had adopted the “long history” of how attachment loss had been determined, i.e. according to the correct albeit overly complicated approach used by Albandar et al. (1999)  but, for the first time, mention “recession” rather than the distance between the cemento-enamel junction and the free gingival margin (which got a minus sign in case of exposed root surface). In my response I wrote,

“[I]f the ways how attachment loss have been determined had been identical in NHANES III and the 2009-2010 NHANES (and indeed any NHANES), one would expect either an apt quotation or a correct reference.

Note that Albandar et al. (1999) did not use the term “recession” at all in their description of what had been considered attachment loss. I find it very awkward that recession (from Latin recessus, retreat) can have a minus sign. I am afraid that future investigators outside the U.S. might refer to Eke et al. (2012) when falsely calculating attachment loss by intuitively and erroneously adding (rather than subtracting) recession and periodontal probing depth. See also the description, apparently written for lay people, of what is meant by recession and attachment loss in Dye et al. (2007) on p. 102 who compare NHANES III and 1999-2004 NHANES data:

“Recession: the presence of exposed [sic!] dental root, which is typically measured in millimeters from the free gingival margin (FGM) to the cemento-enamel junction (CEJ). The FGM is located along the top of the gum and the CEJ is the place on a tooth where the root and the tooth “crown” meet.
“Attachment loss (AL): the amount of connective tissue loss measured in millimeters (mm) from the CEJ to the sulcus base.”

I still would find a brief Corrigendum or Erratum or, say, Note regarding the paper by Eke et al. appropriate and helpful, which might state that attachment loss had been determined in an identical way as had been described by Albandar et al. (1999).

As regards my final suggestion, I am aware that case definitions by Albandar et al. (1999) did include furcation involvement which has not been assessed by Eke et al. (2012). So, direct comparison in order to conclude whether the situation has improved, is stable, or has actually deteriorated will in fact hardly be possible.” (Emphasis as such.)

Well, it is not clear why Dr. Giannobile does not want to publish a short clarifying Note as I had suggested. Yesterday, he briefly answered,

“Thank you for your thoughtful feedback and understanding. I am glad this clarification was helpful. I will pass your suggestions to the authors on the consideration of these issues for their future work.”

I suppose that he has understood that Eke et al. (2012) are not clear but rather misleading and there is apparently need for “consideration of these issues for their future work.”

There is a sneaking suspicion, though (and that is nurtured by the observation that, for the first time in NHANES, prevalence of attachment loss beyond certain thresholds has in all age groups been higher than prevalence of probing depths beyond respective thresholds), that those who had examined the subjects (registered dental hygienists) had just added recession and probing depth, as I had argued in the accompanying email to my letter to the editor.

13 January 2013 @ 5:35 pm.

Last modified January 13, 2013.



  1. Lynne Slim

    Thank you for taking the time by carefully reading the METHODOLOGY section of the Eke et al. paper. I am aware that a much higher prevalence of periodontal disease (PD) was reported than had been reported in the past. It would be nice if the research team went back and re-calculated and am wondering if that would be possible. I’m guessing not and it’s a shame that your letter wasn’t published. In the U.S. not only is the prevalence of PD sensationalized, so too are the perio/systemic links.

    Lynne H. Slim, RDH, MS U.S.A.


    • Muller

      Thanks indeed, Lynne. I suppose, Dr. Giannobile would actually be urged to publish at least sort of a rectifying Note by the authors if more periodontists had pointed to this apparent error. Since he hesitates to do that one gets the impression that there is something to hide. I am afraid that my first impression, i.e. attachment loss had been determined by just adding recession and probing depth, was right.

      Best, Hans-Peter


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