AAP staging and grading of periodontitis (2018): four stages by attachment loss, bone loss and complexity, three grades by rate of progression, with smoking and HbA1c as the modifiers

What it says#

The chart is the AAP's two-page condensation of the classification of periodontitis adopted at the 2017 World Workshop, which the AAP co-presented with the European Federation of Periodontology. Its tables are taken, as the chart says, from Tonetti, Greenwell and Kornman's framework paper in the June 2018 supplement of the Journal of Periodontology, and it points readers to perio.org/2017wwdc for the full suite of reviews, case definition papers and consensus reports. The workshop's consensus report on periodontitis (Papapanou and colleagues, in the same supplement) states the change in one sentence: the forms previously recognized as chronic or aggressive are now grouped under a single category, periodontitis, and are further characterized by a multidimensional staging and grading system.

Staging, the chart says, classifies the severity and extent of a patient's disease from the measurable amount of destroyed tissue and assesses the factors that make long-term management complex. The initial stage is set with clinical attachment loss; if CAL is not available, radiographic bone loss is used. Tooth loss due to periodontitis may modify the stage, and one or more complexity factors may shift it higher. The severity rows: interdental CAL at the site of greatest loss of 1 to 2 mm (Stage I), 3 to 4 mm (Stage II), or 5 mm or more (Stages III and IV); radiographic bone loss in the coronal third at under 15% (I) or 15% to 33% (II), or extending to the middle third of the root and beyond (III and IV); and no tooth loss (I and II), up to 4 teeth lost to periodontitis (III), or 5 or more (IV). The complexity rows: a maximum probing depth of 4 mm or less with mostly horizontal bone loss (I); 5 mm or less with mostly horizontal loss (II); in addition to Stage II complexity, probing depths of 6 mm or more, vertical bone loss of 3 mm or more, class II or III furcation involvement and moderate ridge defects (III); and in addition to Stage III complexity, a need for complex rehabilitation because of masticatory dysfunction, secondary occlusal trauma with tooth mobility of degree 2 or more, severe ridge defects, bite collapse, drifting or flaring, or fewer than 20 remaining teeth (10 opposing pairs) (IV). For each stage the extent is described as localized (under 30% of teeth involved), generalized, or molar/incisor pattern.

Grading aims to indicate the rate of progression, responsiveness to standard therapy and potential impact on systemic health, and the chart instructs clinicians to assume Grade B and seek specific evidence to shift to A or C. The primary criterion is direct evidence: radiographic bone loss or CAL over 5 years of none (Grade A, slow), under 2 mm (Grade B, moderate) or 2 mm or more (Grade C, rapid); whenever available, direct evidence should be used. The indirect criterion is percent bone loss divided by age: under 0.25, 0.25 to 1.0, or over 1.0. A case phenotype row describes heavy biofilm with little destruction (A), destruction commensurate with deposits (B), and destruction exceeding what the deposits explain, with patterns suggesting rapid progression or early onset (C). Two grade modifiers follow: smoking, as non-smoker, under 10 cigarettes a day, or 10 or more a day; and diabetes, as normoglycemic or no diagnosis, HbA1c under 7.0% in a patient with diabetes, or HbA1c of 7.0% or more.

The AAP's FAQ adds the working rules. The most severe area determines the stage. Teeth planned for extraction because of periodontitis count as teeth lost to periodontitis, so a patient who has lost two teeth and needs three more removed is Stage IV. Only one grade is assigned per patient, and a modifier does not move the grade automatically; the FAQ gives the example of a Grade B patient with an HbA1c of 7.2% who may stay at B if the clinician judges the diabetes is not driving the disease, while an HbA1c of 9% would prompt a C. A treated, stable patient is described as having periodontal stability, and the stage typically does not regress, with one exception: a Stage III case whose vertical defect or class II furcation is successfully regenerated can be reclassified as Stage II.

Who it applies to#

Any patient who meets the case definition, which the EFP's guidance sets out from the same framework paper: interdental CAL detectable at 2 or more non-adjacent teeth, or buccal or oral CAL of 3 mm or more with pocketing over 3 mm at 2 or more teeth, provided the loss cannot be ascribed to a non-periodontal cause such as recession of traumatic origin, cervical caries, the distal of a second molar next to a malpositioned or extracted third molar, a draining endodontic lesion, or a vertical root fracture. Every such patient receives one stage, one grade and one extent descriptor for the whole mouth.

It does not make the diagnosis. The AAP's FAQ is explicit that staging and grading do not help the practitioner arrive at a diagnosis; periodontitis is determined first, and the stage and grade supplement it. Gingivitis, periodontal health on a reduced periodontium and the peri-implant diseases have their own categories in the 2018 classification. Necrotizing periodontitis and periodontitis as a direct manifestation of systemic disease are separate forms; the EFP guidance says the latter should be classified by the primary disease's ICD code. And the chart is not a payment document: the FAQ reports that the carriers the AAP met with all said the classification would not affect reimbursement, which continues to rest on the documentation for the treatment rendered.

What changed#

Against the 1999 classification, three things. Chronic and aggressive periodontitis, once treated as different diseases, are one category; the FAQ says research since 1999 failed to document sufficiently distinct biologic features. The severity-only labels of slight, moderate and severe, which could be split by region so a patient had generalized moderate with localized severe disease, gave way to a full-mouth stage that adds tooth loss and complexity of management, and cannot be subdivided. And grading is new: a history-based or estimated rate of progression, with risk factors and systemic impact built in, which the FAQ calls, together with the stage, the guiding stars for difficulty of treatment, prognosis and expectations in maintenance. The consensus statement the FAQ explains, that a periodontitis patient is a periodontitis patient for life, is the practical consequence: a treated, stable patient does not return to the evaluation and maintenance schedule of someone who never had the disease.

Where the source is#

The link under the title opens the AAP's two-page chart, Staging and Grading Periodontitis, whose tables are credited to Tonetti, Greenwell and Kornman, Journal of Periodontology 2018, volume 89, supplement 1, pages S159 to S172. The full papers sit on the Wiley platform, which refused automated access when this entry was written, so the framework and consensus papers were read from their PubMed abstracts and the case definition and workshop history from the EFP's March 2019 guidance notes by Sanz and Tonetti. The AAP's FAQ and its 2017 classification page are listed above. Both societies' documents are free to read; the journal supplement may require a subscription.