What the practice measures before the cleaning

Good prevention begins with measuring. Without findings, every recommendation would be guesswork — and every interval the same for everyone. The values recorded are easy to understand, and it is worth asking about them: they are the only objective information about whether anything is improving.

Pocket depth and PSI

Between tooth and gum lies a groove. With healthy gums it is one to two millimetres deep. If it becomes deeper, one speaks of a pocket: the gum has detached from the tooth, and the area can no longer be reached with a brush.

Measuring is done with a blunt probe bearing a millimetre scale. The Periodontal Screening Index summarises the result in grades from 0 to 4, for each of six sections of the jaw:

• 0 — no findings. No bleeding, no increased depth.
• 1 — bleeding on probing. A gum inflammation that can recede completely.
• 2 — in addition hard deposits or a rough filling margin.
• 3 — pockets of 3.5 to 5.5 millimetres. Here the suspicion of periodontitis.
• 4 — pockets deeper than 5.5 millimetres. Treatment required.

Grades 0 to 2 can be managed with cleaning and better oral hygiene. From grade 3 an X-ray is taken and a full periodontal status recorded, because it then has to be established how much bone has already been lost.

Bleeding is the earliest sign

If the gums bleed on light contact, they are inflamed. That is not a matter of interpretation — healthy gums do not bleed, not even during brushing. This is recorded as the bleeding index: the proportion of examined sites at which it bleeds.

The value is particularly useful because it reacts quickly. Anyone who seriously changes their interdental care sees a markedly lower value at the next session — often within two to three weeks. No other finding gives feedback so rapidly.

Plaque: the plaque index

After staining, the number of sites where plaque lies is counted, particularly in the interdental spaces. A percentage follows from this. It says less about the current state than the bleeding does, but it shows very precisely where the technique is failing. Usually it is the inner surfaces of the lower molars and the back of the last teeth.

Caries history

The DMF-T value counts how many teeth are decayed, filled or lost because of caries. It describes the past, not the future — but the past is the best available indication of future risk. Anyone who has had new caries sites in the last three years belongs in the group with increased risk, regardless of age.

In addition there are saliva tests: flow rate, buffering capacity and bacterial count. They are not routine but can help where someone keeps getting caries despite good oral hygiene.

How numbers turn into an interval

The practice puts the findings together and assigns a risk from them — usually in three grades. The interval to the next session follows from the grade:

• Low: no bleeding, no pockets deeper than 3.5 millimetres, no new caries for years. Check-ups as scheduled, cleaning roughly annually.
• Medium: isolated bleeding sites or isolated deeper pockets. Cleaning roughly every six months.
• High: treated periodontitis, several deep pockets, new caries sites, smoking, diabetes. Follow-up care every three to four months.

Two questions are therefore worth asking at the end of every session: which value did I have this time, and which last time? Anyone who takes that away can judge for themselves whether the effort at home is paying off.