Perio Classification for the INBDE

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Reviewed by
Dr. Ari Rezaei
Key Takeaway
Table of Contents

    In 2017, an update was made to the perio classification system. These are the current guidelines you should use for the INBDE. At the end of this post, we’ll go through some sample diagnoses using this system. 

    Health vs. Periodontal Disease

    It is important to be able to distinguish between healthy and diseased states. Below are features of normal healthy periodontium compared to gingivitis, periodontitis and peri-implant diseases.

    Healthy Periodontium

    • Absence of clinically detectable inflammation
    • Up to one or two sites with some evidence of clinical gingival inflammation
    • Minimal or no bleeding on probing
    • Normal probing depths

    In this state, we see the above perio conditions on an intact periodontium with no attachment or bone loss OR on a reduced periodontium from previous attachment or bone loss that is now stable.


    • Inflammation
    • Erythema, edema, bleeding on probing
    • Normal probing depths

    Patients with gingivitis will have a stable periodontium and no current progressive attachment or bone loss.


    Loss of periodontal tissue support due to microbially associated, host-mediated inflammation.

    • Associated with deeper probing depths
    • Presence of interproximal attachment loss from current disease state; this does not include attachment loss from a history of disease in patients that are currently stable

    The new system utilizes a multidimensional staging and grading system to classify periodontitis.


    Periodontitis staging is determined by the severity, complexity, extent and distribution of disease at presentation. This is categorized into four stages I to IV shown in the table below. It is a measurement of the presentation at this time point and not a reflection of changes over time. 

    Periodontitis Staging

    Step One: Severity

    Initial stage assignment is based on interdental clinical attachment loss at the worst site. 

    Clinical Attachment Loss

    Factors that can also be included in this assessment are radiographic bone loss and tooth loss attributed to periodontitis. If clinical attachment loss is not available, radiographic bone loss should be used.

    Radiographic Bone Loss

    Tooth loss to periodontitis can modify stage:

    Tooth loss

    Step Two: Complexity

    One or more complexity factors may shift the stage to a higher level. This assessment is primarily based on local factors such as probing depth and type of bone loss.

    • Stage I: Maximum probing depth ≤4 mm, mostly horizontal bone loss
    • Stage II: Maximum probing depth ≤5 mm, mostly horizontal bone loss
    • Stage III: In addition to Stage II complexity factors- probing depths ≥6 mm, vertical bone loss ≥3 mm, furcation involvement Class II or III, moderate ridge defects
    • Stage IV: In addition to Stage III complexity factors- need for complex rehabilitation due to occlusal trauma, bite collapse, etc.

    Step Three: Extent and Distribution

    These factors are added to the stage as a descriptor.

    • Localized (less than 30% of teeth involved)
    • Generalized
    • Molar/incisor pattern


    Periodontitis grading aims to indicate the rate of periodontitis progression, responsiveness to standard therapy, and potential impact on systemic health. This is a longitudinal assessment that reflects how disease is changing over time.

    Periodontitis Grading

    When determining grade, clinicians should initially assume grade B and seek evidence to shift to grade A or grade C. 

    • Grade A: slow progression
    • Grade B: moderate progression
    • Grade C: rapid progression

    The grading classification uses primary criteria that should be in the form of direct evidence when possible. Direct evidence of progression is radiographic bone loss or clinical attachment loss.

    • Grade A: no loss over 5 years
    • Grade B: less than 2mm over 5 years
    • Grade C: ≥2 mm over 5 years

    Indirect evidence of progression includes % bone loss divided by age and case phenotype.

    • Grade A: less than 0.25, heavy biofilm deposits with low levels of destruction
    • Grade B: 0.25 to 1, destruction corresponds to biofilm deposits
    • Grade C: greater than 1, destruction exceeds biofilm deposits, specific patterns indicative of periods of rapid progression or early onset disease

    Grade modifiers include risk factors such as smoking or diabetes;

    • Grade A: non-smoker, normoglycemic/no diagnosis of diabetes
    • Grade B: less than 10 cigarettes per day, HbA1c less than 7% in patients with diabetes
    • Grade C: ≥10 cigarettes per day, HbA1c ≥7.0% in patients with diabetes

    Peri-Implant Diseases and Conditions

    Just like any tooth root, implants have their own surrounding periodontium and peri-implant tissues. They are susceptible to a variety of conditions and diseases, which includes peri-implant mucositis, peri-implantitis and healthy peri-implant periodontium.

    Healthy peri-implant periodontium

    • Absence of visual signs of inflammation and bleeding on probing
    • Health is possible around implants with normal or reduced bone support
    • Isolated timepoint probing depths are not used since normal probing depths are not defined for implants

    Peri-implant mucositis

    • Signs of inflammation and bleeding on probing
    • Absence of progressive bone loss


    • Signs of inflammation and bleeding on probing
    • Increased probing depths compared to baseline
    • Presence of progressive bone loss


    Case 1

    Case 1 Patient Information

    Panoramic radiograph:

    Panoramic Radiograph

    Full mouth series:

    FMX for Case 1
    Periodontal Charting:


    Maxillary Periodontal Charting


    Mandibular Periodontal Charting

    What is the periodontal diagnosis?

    The first step is to determine the stage of periodontitis. 

    Periodontal Stage

    We start by assessing the clinical attachment loss at the worst site. In this patient, we can see clinical attachment loss far greater than 5mm. There is also radiographic bone loss extending to the middle third of the root and beyond. In addition to this, the patient is missing more than 5 teeth. We also need to consider the need for complex rehabilitation due to tooth mobility. 

    This patient’s condition aligns with Stage IV based on the factors listed above. The extent and distribution would be described as generalized since more than 30% of teeth are involved. 

    We then move on to classify the grade of periodontitis. 

    Periodontitis Grading

    To classify grade, we initially assume grade B (moderate rate of progression) and seek evidence to move to either grade A or grade C. We are not provided with direct evidence of progression, so we need to move to other criteria to make our decision. This would include the risk factor of uncontrolled diabetes with a HbA1c of 8.1%.  We can also look at % bone loss over patients' age. This patient is 56 years old. We can look and see that the worst sites have about 90% bone loss. This makes the ratio for this patient greater than one. These factors indicate rapid progression, which is grade C periodontitis.

    Putting our two diagnoses together, this patient has Stage IV, Grade C periodontitis.

    Case 2

    FMX for Case 2

    Full mouth series: 

    Periodontal Charting:



    Mandibular Periodontal Charting

    What is the periodontal diagnosis?

    Once again we start with the assessment of the stage. 

    Periodontal Stage

    The patient has clinical attachment loss that exceeds 5 mm in multiple areas. In terms of radiographic bone loss, we can see bone loss extending to the middle third of the root and beyond. We also need to consider the need for complex rehabilitation due to tooth mobility and flaring. This aligns with a Stage IV diagnosis. We can add a description of molar/incisor pattern for this patient given the severity of loss around these teeth in the radiographs.

    We then continue on to assess the grade of this patient.

    Periodontal Grading

    For this patient, we are not given a history that includes direct evidence of progression. However, we are given the patient’s age. Age 25 suggests early onset of disease. We also know that the destruction far exceeds expectations given biofilm deposits. This supports a rapid rate of progression and a Grade C diagnosis.

    We can conclude that this patient has Stage IV Grade C periodontitis. 


    The two patients in our cases have different presentations and risk factors, and we are provided with different information to make a diagnosis. However, using the new staging and grading system, we arrive at the same classification. It is important to follow the metrics of the system to properly identify the stage and grade.

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