Staging and Grading Periodontitis

October 12th, 2021 - Christine Woolstenhulme, QCC, QMCS, CPC, CMRS
Categories:   Coding   Dental  

We now understand periodontitis may present itself as a manifestation of systemic diseases in fact; according to DeltaDental, research shows that more than 90 percent of all systemic diseases have oral manifestations, including swollen gums, mouth ulcers, dry mouth, and excessive gum problems. Some of these diseases include:

  • Diabetes
  • Leukemia
  • Oral cancer
  • Pancreatic cancer
  • Heart disease
  • Kidney disease

Baby boomers are especially vulnerable to developing diabetes, osteoporosis, and heart disease, the risks of which increase with age. Researchers believe that symptoms of these conditions can manifest in the mouth, making dentists key in diagnosing the diseases. For example:

  • Bad breath and bleeding gums could be indicators of diabetes.
  • Dental x-rays can show the first stages of bone loss.
  • A sore and painful jaw could foreshadow an oncoming heart attack.

Continued research and findings supporting the association between periodontal disease and systemic disease assists with advancement toward improving outcomes and lowering risk factors.

In 1999 periodontitis was represented as a disease entity as either chronic or aggressive according to the ADA, however, this left out important biologic features to distinctly identify between the two and have since been regrouped simply as "periodontitis". We now classify based on staging the full mouth instead of severity alone.  In addition, we use grading to incorporate history, progression, and use risk factors as a way to determine the impact of a patient's general overall health. 

Staging Periodontitis

The following information on staging is available from the American Academy of Periodontology;

Stage I periodontitis (mild disease) patients will have probing depths ≤4 mm, CAL ≤1-2 mm, horizontal bone loss, and will require non-surgical treatment. No post-treatment tooth loss is expected, indicating the case has a good prognosis going into maintenance.

Stage II periodontitis (moderate disease) patients will have probing depths ≤5 mm, CAL ≤3-4 mm, horizontal bone loss, and will require non-surgical and surgical treatment. No post-treatment tooth loss is expected, indicating the case has a good prognosis going into maintenance.

Stage III periodontitis (severe disease) patients will have probing depths ≥6 mm, CAL ≥5 mm, and may have vertical bone loss and/or furcation involvement of Class II or III. This will require surgical and possibly regenerative treatments. There is the potential for tooth loss from 0 to 4 teeth. The complexity of the implant and/or restorative treatment is increased. The patient may require multi-specialty treatment. The overall case has a fair prognosis going into maintenance.

Stage IV periodontitis (very severe disease) patients will have probing depths ≥6 mm, CAL ≥5 mm, and may have vertical bone loss and/or furcation involvement of Class II or III. Fewer than 20 teeth may be present and there is the potential for tooth loss of 5 or more teeth. Advanced surgical treatment and/or regenerative therapy may be required, including augmentation treatment to facilitate implant therapy. Very complex implant and/or restorative treatment may be needed. The patient will often require multi-specialty treatment. The overall case has a questionable prognosis going into maintenance.

Factors Considered

  • CAL -interdental clinical attachment loss
  • Tooth Loss
  • Stage I and II - probing depths
  • Radiographic bone loss
  • Stage III and IV- furcation involvement, ridge defects, and bite collapse 

Other Considerations for Staging Periodontitis 

  • Staging pertains to the whole mouth and is relative to the area with the highest severity and most complex portion of the mouth.
  • Staging is based on the amount of damage that the disease has already progressed to. 
  • Tooth Loss or planned extractions due to Periodontitis is included as a part of active periodontal therapy. 
  • Each complexity moves the staging to the next higher stage.
  • Once a patient is clinically stable they are considered as having periodontal stability, the staging may develop to a higher stage, but not generally to a lower stage.

    NOTE:   According to the American Academy of Periodontology (AAP), "there is one exception to this rule. For instance, if the case was classified as Stage III due to the presence of a vertical defect ≥3 mm or Class II furcation involvement and those sites were successfully regenerated such that the CAL throughout the dentition is now 3-4 mm, the furcation involvement is a Class I or not clinically detectable, and probing depths are ≤5 mm, the stage could change from Stage III to Stage II."

Periodontitis Staging Table











≤4 mm

≤5 mm

≥6 mm

≥6 mm


≤1-2 mm

≤3-4 mm

≥5 mm

≥5 mm


Coronal third(<15%)

Coronal third(15-33%)

Extends beyond 33% or root

Extends beyond 33% of root







No Tooth Loss

No Tooth Loss

≤4 teeth

≥5 teeth


  • Non-surgical
  • Non-surgical
  • Surgical
  • Surgical
  • Possible regenerative
  • Possible multi-specialty care
  • Advanced surgical
  • Possible regenerative
  • Possible augmentation
  • Complex implant and/or restorative
  • Often multi-specialty care






Grading Periodontitis

The grading system helps us determine further progression and helps to identify at what rate the disease may progress. Grading also plays an important part in determining the anticipated response to treatment as well as the potential impact progression may have on their overall health.  Grading uses indicators of the disease and considers damage from any previous active disease. For example, is the patient a smoker or have diabetes? These are risk factors that will help determine the progression of the disease. There is also direct and indirect evidence of progression which is considered in grading such as the % of bone loss and the patient's age.   

Periodontitis Grading Table

Grade A:


Grade B:


Grade C:



No loss over 5 years

< 2 mm over 5 years

≥ 2 mm over 5 years


< 0.25

0.25 to 1.0

> 1.0


Low levels of destruction with biofilm deposits

Moderate levels of destruction with biofilm deposits

Excessive levels of destruction from biofilm deposits; clinical patterns denote rapid progression and/or early-onset disease



< 10 cigarettes/day

≥10 cigarettes/day


Normoglycemic/no diagnosis of diabetes

HbA1c < 7.0% in patients with diabetes

HbA1c ≥ 7.0% in patients with diabetes

Using both Staging and Grading for the Complete Picture

A patient may be in remission and considered a grade "A", which is an indication of low progression, or a slow rate but also have a stage III indicating previous damage.  Using both the staging and the grading gives a more complete assessment of the patient's risk and the expected progression, using an evidenced-based plan for treatment. 

We can see where a diabetic patient with HbA1c of 8.0% (grade C is HbA1c>7.0%) may be a Stage II but has a Grade C periodontitis.  Therefore, the diagnosis would be Stage II Grade C Periodontitis.


Questions, comments?

If you have questions or comments about this article please contact us.  Comments that provide additional related information may be added here by our Editors.

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