The BSP 2017 Perio Classification: A Simplified Guide & Calculator

The “Mental Math” Problem

If you are like most dentists, the transition from the 1999 classification (Chronic/Aggressive) to the 2017 World Workshop classification has added a layer of cognitive load to every exam.

While the new system is biologically better, calculating “% Bone Loss ÷ Age” ratios in your head while a patient is waiting isn't easy.

We built the tool below based on the Healthy Gums DO Matter (HGDM) toolkit to automate the math for you.

The Cheat Sheet: How the Logic Works

This tool follows the BSP Implementation of the 2017 classification, which simplifies the complex World Workshop rules for UK General Practice. Here is the evidence-based breakdown of how we determine the diagnosis.

1. Staging (The Severity)

Staging is based on the worst site of interproximal bone loss in the mouth. The HGDM toolkit (Page 16) maps percentage bone loss to the anatomical thirds of the root:

• Stage I (Early/Mild): Bone loss <15% (or <2mm attachment loss).
• Stage II (Moderate): Bone loss in the Coronal Third (15% to 33%).
• Stage III (Severe): Bone loss in the Mid Third (33% to 66%).
• Stage IV (Very Severe): Bone loss in the Apical Third (>66%).

2. Grading (The Speed of Progression)

Grading estimates how susceptible the patient is to disease progression. The BSP implementation uses a simple ratio calculation: % Bone Loss ÷ Patient Age.

• Grade A (Slow): Ratio < 0.5
  (Example: A 60-year-old with 20% bone loss. 20÷60 = 0.33)
• Grade B (Moderate): Ratio 0.5 – 1.0
  (Example: A 50-year-old with 40% bone loss. 40÷50 = 0.8)
• Grade C (Rapid): Ratio > 1.0
  (Example: A 40-year-old with 50% bone loss. 50÷40 = 1.25)

3. Extent (Distribution)

This describes how widespread the disease is (HGDM Page 18):

• Localised: Affecting <30% of teeth.
• Generalised: Affecting >30% of teeth.
• Molar/Incisor Pattern: A specific pattern often seen in Grade C cases.

What About Smokers and Diabetics?

In the BSP implementation, risk factors like smoking and diabetes are documented alongside the diagnosis, rather than changing the Grade calculation directly (HGDM Page 18).

A complete diagnosis statement should look like this (HGDM Page 19):

Need a Full Periodontal Assessment?

This calculator is great for a quick radiographic check. However, a full periodontal assessment requires tracking Plaque Scores, Bleeding Scores, and Patient Engagement.

The Dentistry Dashboard automates the entire Healthy Gums DO Matter pathway, including:

• Modified Plaque & Bleeding Scores (Ramfjord teeth).
• Engagement Tracking: Automatically determines if a patient qualifies for Root Surface Debridement based on their OHI improvements.
• Stability Status: Tracks if the disease is Stable, In Remission, or Unstable.

Start your free trial today and eliminate the guesswork from your perio assessments.