Applying the new periodontal disease classification (2017) in general dental practice

A new perio classification… What? another one?

Hasn’t it always felt like there is a new perio disease classification, or a new one coming soon?

Although this is not exactly endodontics, it is still relevant. Apart from anything else, to communicate effectively we all need to talk the same dialect and it looks like this new 2017 classification, produced jointly by the AAP and ESE is here to stay!

Initial impressions are that it looks complicated and, although admittedly it is comprehensive, I don’t think the original publication in the Journal of Clinical Periodontology makes understanding very easy or helps much with incorporating it into the average general dental practice. I dare say there will be many explanatory article along in the near future (Update Jan 2019, look at this article from the BDJ and this article from Dental Update) which will make it easier to understand, but in the mean time this is my take on how to make it easy to use in practice.

Bear in mind that this is a classification of periodontal disease, not a system of diagnosis. So, for it all to make sense in clinical practice you will need to supplement it with a bit more information… specifically your probing depths and bleeding indices.

What has changed?

The classification incorporates various categories of gingival/periodontal health (because you can have a reduced periodontium that is healthy), gingival diseases, periodontal diseases and a classification of peri-implant health and disease. 

There are no longer chronic or aggressive periodontitis categories. These are no longer treated as separate entities as they have been subsumed into a new staging and grading of periontitis.

What does a periodontitis diagnosis look like now?

Using the new classification, various elements of the patient’s disease are built up into a diagnosis. Before explaining the process, it will help you to see an example of a diagnosis based on the new classification, so you can see where we are going with this….

Generalised | Periodontitis | Stage 3, Grade 3 | currently unstable | with risk factors of smoking (20/day) and poorly controlled diabetes.

So, keeping that in mind, let’s start with an abridged overview of the classification. For a more comprehensive version see this article in the Journal of Periodontology.

  • Periodontal Health and Gingival Diseases Periodontal health (intact or reduced periodontium), Gingival Diseases (biofilm induced), Gingival diseases (non-biofilm induced)
  • Periodontitis Periodontitis, Necrotising periodontal disease, Periodontitis, Periodontitis as manifestation of systemic disease
  • Other conditions of the Periodontium Systemic diseases affecting periodontium, Periodontal abscess, Endo-Perio lesions, Mucogingival deformities/conditions, Traumatic occlusion, Tooth/prosthesis related factors
  • Peri-Implant Dieases (which I am ignoring for now)

In practice, once you’ve screened your patient (that is, done a BPE) and consequently decided you need to do a full periodontal assessment, you may well have decided they have a diagnosis of periodontitis. With the new classification, once you have arrived at a periodontitis diagnosis, you then need to look at the stage and grade, which quantify the historical severity of disease and the historical rate of disease progression. The extent of the disease is classified as localised, generalised or a molar-incisor pattern. Then, the current disease activity is classified as stable, in remmision or unstable. Finally, an assessment of risk factors is required.

How exactly does this work in practice?

With regards to a diagnosis of periodontitis, I suggest that a logical and doable implementation in general dental practice will go along the lines of….

1. BPE

Start with a BPE and also broadly assess interdental bone loss (either radiographically or clinical attachment loss)…

  • Code 0,1,2 = Gingivitis
  • Code 3 with no evidence of bone loss = Gingivitis (false pocketing)
  • Code 3 with evidence of bone loss = Periodontitis
  • Code 4 = Periodontitis

There is a little gotcha here with the code 3 – if it is a Code 3 with no evidence of interdental bone loss (e.g. gingivitis with false pocketing) do a round of OHI / debridement. Redo the pocket chart at 3/12 and if all pockets are <4mm with no loss of attachment then the classification is gingivitis otherwise it is periodontitis.

If the patient has periodontitis they need a full perio assessment, CAL, radiographs, indices. Then…….

2. Extent

Establish the extent of the problem…

  • localised (<30% teeth involved)
  • generalised (≥30% teeth involved)
  • molar-incisor pattern

3. Stage and Grade

Now, establish the Stage (historical severity of bone loss) and Grade (historical rate of progression)…

Remember these are just assessments of historical disease progress. The stage and grade are established at presentation and do not change, even after succesful treatment. The improvement in the patient’s disease status becomes encapsulated in a change of (for example) currently unstable to currently stable (see later).

Stage is ideally assessed by measuring clinical attachment loss (CAL), that is pocket depth+gingival margin position OR by assessing interdental radiographic bone loss (RBL) OR number of missing teeth.

In terms of RBL:

  • Stage 1 (<15%)
  • Stage 2 (In coronal 1/3 but more than 15%, that is 15-33%)
  • Stage 3 (>33%)
  • Stage 4 (>33%)

In terms of CAL:

  • Stage 1 (1-2mm)
  • Stage 2 (3-4mm)
  • Stage 3 (≥5mm)
  • Stage 4 (≥5mm)

In terms of tooth loss (due to periodontitis only, so this is only possible if you have a reliable history):

  • Stage 1 or 2 (no tooth loss)
  • Stage 3 (≤4 teeth)
  • Stage 4 (5 or more teeth)

The divider between Stage 3 and Stage 4 seems to have more than one definition, depending on what you read. Either, Stage four is actually >66% RBL, or it is designated as anything that is Stage 3 with complex management issues such as occlusal factors, severe splaying of teeth, severe ridge defects, less than 10 opposing pairs of teeth remaining. Essentially, you can probably subjectively tell a Stage 3 from Stage 4 just by looking at it!

Grade is assessed by looking at the historical rate of progression, either from sequential CAL, or radiographic records or by doing a quick calculation of the maximum percentage of bone loss / age. To make it easy for you, asssume a patient is Grade B, unless there is evidence that they are Grade A or C.

In terms of progressive bone loss or CAL:

  • Grade A (none)
  • Grade B (<2mm/5 years)
  • Grade C (≥2mm/5 years).

In terms of ratio of maximum % bone loss / age:

  • Grade A (<0.25)
  • Grade B (0.25-1.0)
  • Grade C (>1).

So, that is the assessment of the position the tissues which, as I said, is based on historical data.

4. Current Activity

For a full diagnosis we also need to know the current disease activity…

For that we need to turn to the probing depths and bleeding indices, giving us Stable / In Remission/ Unstable.

  • If BoP index is <10% and PPD ≤4mm and there is no BoP at the 4mm sites then the disease is Currently Stable
  • If BoP index is ≥10% and PPD is ≤4mm and there is no BoP at the 4mm sites then the disease is Currently In Remission
  • If PPD is ≥5mm or PPD is ≥4mm with BoP at these sites then the disease is Currently Unstable

5. Risk Factors

Nearly there now. We just need to do a risk factors assessment…

Are they a smoker?

  • No
  • <10/day
  • ≥10 day

Are they diabetic?

  • No
  • HbA1c <7%
  • HbA1c ≥7% (sub-optimal control)

Unlike what is implied in the AAP literature, the diabetes and smoking risk assessments do not “trump” the grading category (provided by assessing the rate of bone loss or % bone loss/age ratio), they form a coda to the grading.

So, returning to where we started, a diagnosis may well be….

Generalised | Periodontitis | Stage3, Grade3 | currently unstable | with risk factors of smoking (20/day) and poorly controlled diabetes.

…… Easy!


Dietrich, T., Ower, P., Tank, M., West, N.X., Walter, C., Needleman, I., Hughes, F.J., Wadia, R., Milward, M.R., Hodge, P.J. and Chapple, I.L.C., 2019. Periodontal diagnosis in the context of the 2017 classification system of periodontal diseases and conditions–implementation in clinical practice. British dental journal226(1), p.16

G. Caton, J., Armitage, G., Berglundh, T., Chapple, I.L., Jepsen, S., S. Kornman, K., L. Mealey, B., Papapanou, P.N., Sanz, M. and S. Tonetti, M., 2018. A new classification scheme for periodontal and peri‐implant diseases and conditions–Introduction and key changes from the 1999 classification. Journal of periodontology89, pp.S1-S8.

Ower, P., 2019. New classification system for periodontal and peri-implant diseases. Dental Update, 46(1), p.8-11

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