Periodontitis Stages and Grades: What Does the 2017 Classification Tell You?

Periodontitis is a chronic inflammatory disease, driven by bacterial plaque, of the tissues that surround and support the teeth (the gums, connective tissue and jawbone). The current classification adopted in 2017 does not simply describe this disease as "present" or "absent"; it expresses how far the disease has progressed with a stage and how quickly it tends to progress with a grade. In this article, we explain what terms such as "Stage III, Grade B" that you may see in your examination report mean.

What is the 2017 classification of periodontal diseases?

The 2017 classification is the current classification of periodontal diseases, developed at a joint workshop of the American Academy of Periodontology (AAP) and the European Federation of Periodontology (EFP) and published in 2018. It removed the previously used distinction between "chronic periodontitis" and "aggressive periodontitis," bringing the disease together under a single heading.

In the current system, periodontitis is described in three dimensions:

• Stage (I–IV): The severity of the disease and how complex its treatment will be,
• Grade (A–C): The rate of progression of the disease and its risk factors,
• Extent: How the disease is distributed in the mouth.

Much like the staging systems used in other areas of medicine, this approach provides both the current status of the disease and a prediction of its future course.

What are the stages of periodontitis?

The stage indicates the severity of the disease and the complexity of treatment. It is determined by considering clinical attachment loss between the teeth (how far the gum and connective tissue have separated from the tooth), bone loss seen on X-rays, the number of teeth lost due to periodontitis, and factors that complicate treatment.

Stage I: Initial periodontitis

Interdental attachment loss is 1–2 mm; bone loss is within the coronal (upper) third of the root length and below 15 percent. There is no tooth loss due to periodontitis; probing depths generally do not exceed 4 mm, and bone loss is mostly horizontal.

Stage II: Moderate periodontitis

Attachment loss is 3–4 mm; bone loss is within the coronal third of the root, in the range of 15–33 percent. There is no tooth loss; probing depths are generally up to 5 mm, and bone loss is mostly horizontal.

Stage III: Severe periodontitis with potential for additional tooth loss

Attachment loss is 5 mm or more; bone loss extends to the middle third of the root or beyond. Four or fewer teeth may have been lost due to periodontitis. Pockets of 6 mm or more, vertical bone loss of 3 mm or more, or involvement of the area between the roots of molars (furcation) complicate treatment.

Stage IV: Severe periodontitis with potential for loss of most of the teeth

In addition to tissue loss similar to Stage III, 5 or more teeth have been lost due to periodontitis. Comprehensive oral rehabilitation is needed because of problems such as impaired chewing function, marked tooth mobility and drifting, bite collapse, or fewer than 20 remaining teeth.

What do periodontitis grades tell you?

The grade helps predict the rate of progression of the disease and the expected response to treatment. There are three grades:

• Grade A – slow progression: No additional bone or attachment loss over the past 5 years; little tissue destruction despite heavy plaque buildup.
• Grade B – moderate progression: Less than 2 mm of loss over 5 years; tissue destruction is consistent with the amount of plaque.
• Grade C – rapid progression: 2 mm or more of loss over 5 years; tissue destruction exceeds what would be expected from the amount of plaque, or the disease began at an early age.

Because previous records are not always available, the grade is often estimated indirectly: the percentage of bone loss at the most affected tooth is divided by the person's age. If this ratio is below 0.25, Grade A is considered; between 0.25 and 1.0, Grade B; and above 1.0, Grade C. Grade B is assumed at the outset and then shifted to A or C based on the findings.

Smoking and diabetes can change the grade

In the classification, two important risk factors can raise the grade:

• Smoking: Fewer than 10 cigarettes a day can raise the grade to at least B, and 10 or more a day to C.
• Diabetes: In people with diabetes whose HbA1c is below 7.0 percent, the grade can be raised to at least B; in those at 7.0 percent or above, to C.

We cover these topics in detail in our articles on smoking and gum disease and gum disease and general health.

How is the extent of periodontitis described?

Extent refers to how the disease is distributed in the mouth. If fewer than 30 percent of the teeth are affected, it is described as localized periodontitis; if 30 percent or more are affected, as generalized periodontitis. When the disease is concentrated in the first molars and incisors, the term molar-incisor pattern is used; this pattern is seen more often in young people and in rapidly progressing forms.

How do stage and grade affect treatment?

Stage and grade help determine the scope of treatment and how often check-ups are needed. The EFP's S3-level clinical practice guideline describes the treatment of Stage I–III periodontitis as a stepwise approach:

1. Step one: Explaining the disease, oral hygiene instruction, removal of plaque and tartar above the gumline, and control of risk factors such as smoking and diabetes.
2. Step two: Non-surgical treatment in which tartar and bacterial deposits below the gumline are removed.
3. Step three: Repeated or surgical treatment, when needed, for deep pockets that have not responded adequately.
4. Step four: Supportive periodontal care at regular intervals to maintain the improvement achieved.

In Stage IV periodontitis, in addition to these steps, multidisciplinary treatment involving fields such as orthodontics, prosthodontics and implants may be needed. In Grade C, controlling risk factors and frequent check-ups become even more important. For the treatment process, see our gum disease treatment page.

When should you see a dentist?

If you notice bleeding gums, bad breath, gum recession, or loose or shifting teeth, you should see a dentist or a periodontist. Stage and grade can only be determined through a clinical examination, gum pocket measurements and X-ray evaluation; it is not possible for a person to estimate their own stage based on symptoms.

The doctoral thesis of periodontist Dr. Nadin Gemrekoğlu, DDS, PhD, focused on the effects of initial periodontal therapy on clinical and biochemical parameters. Examination findings are explained to the patient within the framework of this classification, and treatment is planned individually. To make an appointment, please visit the contact page.