How to read a periodontal chart

Each tooth is probed at six sites: mesiobuccal, buccal and distobuccal on the cheek side, and distolingual (or distopalatal), lingual and mesiolingual on the inner side. The chart shows the outer (buccal) and inner (palatal or lingual) readings on either side of a row of FDI tooth numbers, laid out as if you are facing the patient.

Above and below each tooth sit the per-tooth readings, mobility and furcation, and the per-site rows: bleeding on probing, plaque, gingival margin and probing depth.

Probing depth is the distance in millimetres from the gingival margin to the base of the pocket. In a healthy, intact periodontium the 2017 consensus describes probing depths of 3 mm or less, with fewer than 10% of sites bleeding.

Deeper readings are pockets. After treatment, the BSP flow chart treats residual pockets of 4 to 5 mm as sites to instrument again, and suggests considering referral for pockets of 6 mm or more. Probing depth alone doesn't tell you how much support has been lost, though; for that you need the gingival margin too.

The gingival margin row records where the gum sits relative to the cementoenamel junction (CEJ). Charts differ in the sign they use, so check which convention a chart follows. A common one, and the one FindClinica's chart uses, records recession (margin below the CEJ) as a positive number and a margin above the CEJ (overgrowth, or a margin covering enamel) as a negative number.

With that convention, clinical attachment level (CAL) = probing depth + gingival margin. CAL is the real measure of attachment lost, because it is measured from a fixed point, the CEJ, rather than from the gum, which moves.

Mark each site that bleeds within a few seconds of probing. The BOP score is the percentage of sites that bled: bleeding sites ÷ sites probed × 100. On a full chart of 28 teeth that's 168 sites, so 17 bleeding sites is about 10%.

Under the 2017 classification, a patient with an intact periodontium and BOP of 10% or more has gingivitis: localised at 10 to 30%, generalised above 30%. Below 10% with shallow pockets is gingival health.

The most useful thing about BOP is what its absence tells you. In Lang's study of maintenance patients, sites that didn't bleed had a negative predictive value of 98% for future attachment loss, while a bleeding site on its own predicted loss in only about 6% of cases. Sites that bled at every visit were far more likely to lose attachment than sites that never bled.

The plaque row marks the surfaces with plaque. O'Leary's plaque control record turns it into a percentage: surfaces with plaque ÷ surfaces examined × 100. It is mainly a teaching tool for the patient: show them the score, then show them the drop at the next visit. The BSP flow chart uses a plaque score of 20% or less as a sign that the patient is engaged with home care.

Mobility is graded 0 to 3: 0 is normal physiological movement, 1 slight, 2 moderate, and 3 severe, where the tooth also moves up and down in its socket.

Furcation involvement is recorded on multi-rooted teeth. Two systems are common.

The 2017 AAP/EFP classification stages periodontitis by severity and complexity, mainly from interdental CAL at the worst site, and grades it by rate of progression.

Chart the full mouth before treatment and again at re-evaluation; the BSP flow chart re-evaluates about three months after the second step of therapy. For patients in maintenance, the BSP recommends recording full probing depths at least once a year, and the European S3 guideline recalls them every 3 to 12 months depending on their risk. Comparing the charts is the point: the same chart type, the same sites, a few months apart.

For a paper chart with exactly these rows, print the free periodontal chart. In FindClinica the same chart is built in: click a site and pick the number, deeper pockets are coloured, and each chart is saved as an initial exam, re-evaluation or maintenance visit on the patient's file, so the next comparison is one click away. Step by step: the perio chart in FindClinica.