How to Measure Attachment Loss

As I have mentioned in a previous post I had sent a letter to the editor of Journal of Dental Research, Professor W. Giannobile, in which I had asked the authors of a recent article on the periodontal findings of the 2009-2010 NHANES for some clarification regarding the quite confusing definition of attachment loss. There, Eke et al. (2012) wrote in the Material and Methods section,

“All periodontal examinations were conducted in a mobile examination center (MEC) by dental hygienists registered in at least one U.S. state. Gingival recession [= the distance between the free gingival margin (FGM) and the cemento-enamel junction (CEJ)] and pocket depth (PD) (= the distance from FGM to the bottom of the  sulcus or periodontal pocket) were measured at 6 sites per tooth (mesio-, mid-, and disto-buccal; mesio-, mid-, and disto-lingual) for all teeth, excluding third molars. For measurements at each site, a periodontal probe (Hu-Friedy PVP 2TM, Chicago, IL, USA) with 2-, 4-, 6-, 8-, 10-, and 12-mm graduations was positioned parallel to the long axis of the tooth at each site. Data were recorded directly into an NHANES oral health data management program that instantly calculated attachment loss (AL) as the difference between probing depth and recession. Bleeding from probing and the presence of dental furcations were not assessed.” (Emphasis added.)

In my letter [pdf] I had pointed to (1) a possible glitch when calculating attachment loss as the difference, rather than the sum, between probing depth and recession; and (2) the fact that in the absence of any recession, periodontal probing depth must not automatically be regarded as attachment loss as the above description of the method suggested. I had provided a most trivial example regarding a 4 mm probing depth without recession which may be associated with either 0, 1, 2, 3, or 4 mm attachment loss, but it seems that the NHANES oral health data management program would have “instantly calculated” 4 mm. Then, (3) I had expressed my concern that either observation that attachment loss at certain thresholds was consistently higher than periodontal probing depth at respective thresholds in all age groups of the adult population of the United States, and the rather conspicuous finding that moderate periodontitis occurred at much higher prevalence than mild periodontal disease may in part be due to the apparently amended definition of attachment loss. And finally, as a constructive suggestion, (4) I asked the authors to compare the new 2009-2010 data with those of 1988-1994 by using the previous case definition (solely based on probing depth) by Albandar et al. (1999) in order to be able to  “forget what I was told”, namely that prevalence, extent and severity of periodontal disease had in fact not decreased since NHANES III.

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How to Teach Epidemiology to Undergraduates: Forget What You Were Told

I had been quite comfortable with teaching the results obtained in NHANES III (the population-based 3rd National Health and Nutrition Examination Survey the data of which had been collected between 1988 and 1994) for a long time. In a nutshell, for the adult, dentate (those with teeth) population of the United States Albandar and Kingman (1999) had reported that,

  • gingival inflammation (as assessed by bleeding on probing) is widespread with increasing prevalence (at least one bleeding site) from 40-50% in 30 to 39-yr-olds to around 60% in 80-plus-yr-olds, as well as increasing extent (mean % teeth with gingival bleeding) from about 13 to 23%;
  • likewise, calculus is widespread with prevalence in 90-95% of subjects and increasing, with age, extent from 40-50% to more than 60% teeth; and
  • while males had significantly more gingival bleeding, more subgingival calculus and more teeth with either supra and subgingival calculus than females, non-hispanic blacks had the highest prevalence and extent of dental calculus.

When it comes to periodontitis, Albandar et al. (1999) observed that,

  • at least 35% of the adult population were affected by the disease, but most cases (22%) were mild;
  • moderate and advanced periodontitis affected not more than 13%;
  • not surprisingly, prevalence and extent of attachment loss increased with age while in the oldest age group (80 yr and older), prevalence of deep pockets decreased because of tooth loss and recession; and,
  • severe forms of the disease affected more men and more African Americans and Hispanics than Whites.

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