The numbers called out during periodontal charting are pocket depths, measured in millimetres, recording how far a fine probe slides into the space between the gum and the tooth. They are one part of a larger record, and no single number on its own decides what treatment is needed.
Hearing a clinician call out a string of numbers can be unsettling, particularly when one of them is higher than the rest. Knowing what is being measured makes the whole appointment easier to sit through.
If numbers were read out at your last visit and nobody explained them, it is entirely reasonable to ask.
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What is the probe actually doing?
A periodontal probe is a thin, blunt-ended instrument marked with millimetre graduations, rather like a very small ruler. It is walked gently around each tooth and slid into the natural crevice between the gum and the tooth surface.
The depth at which it stops is the pocket depth. In health, the gum is attached close to the top of the root and the probe stops shallow. Where inflammation has broken down attachment and bone, the probe travels further before it meets resistance.
Six sites are usually recorded per tooth, three on the cheek side and three on the tongue side, which is why so many numbers get called out. A full chart is a map, not a verdict.
What do the depths broadly indicate?
As a rough guide, 1–3mm is generally consistent with health, 4–5mm suggests early to moderate disease, and 6mm or more indicates more advanced breakdown around that tooth.
Those ranges are a starting point for a conversation, not a diagnosis. A number can be deeper because the gum is swollen rather than because bone has been lost. It can be affected by how firmly the probe was used, by a large filling edge, or by where the tooth sits in the arch.
So please do not self-diagnose from a number overheard across the room. A pocket depth is interpreted alongside the X-rays, the bleeding pattern, the gum level and the patient's history. On its own it means considerably less than it appears to.
What else is recorded?
- Bleeding on probing — whether the site bleeds when the probe is placed.
- Recession — how far the gum margin has moved down the root, which changes what a given pocket depth means.
- Mobility — whether a tooth moves when tested, graded on a simple scale.
- Furcation involvement — whether bone loss has reached the point where the roots of a multi-rooted tooth divide.
- Plaque score — how much plaque is present and, importantly, where it is being missed.
Photographs of the front teeth are often taken alongside the chart so that progress can be seen rather than described.
Why does bleeding on probing matter more than the depth?
A pocket depth is a measure of damage that has already happened. Bleeding on probing is a measure of what is happening now.
A 5mm pocket that does not bleed is generally a stable, treated site: the depth is historical, and the tissue at the bottom of it is no longer inflamed. A 4mm pocket that bleeds at every visit is an active site, and it is the one that will keep deteriorating if nothing changes.
That is why a clinician often seems more interested in the bleeding pattern than in the largest number on the chart. Reducing bleeding is the practical goal of treatment. Background on gum disease generally is available from healthdirect.
A chart takes one appointment and gives you a baseline you can be measured against later.
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Why keep a full chart at all?
Because gum disease is judged by change over time, not by a snapshot. A full chart recorded today is the record that next year's chart is compared against.
Without it, there is no way to tell whether a 5mm pocket has been 5mm for a decade or arrived in the past eight months. Those two situations call for very different responses, and only a record distinguishes them. What is easy to miss without one is set out in perio analysis and what can be missed.
Is charting an extra cost?
A periodontal screening, known as a PSR, is included in the $250 check-up, X-rays and clean, and in the $120 consultation. It is a quick screen that indicates whether a full chart is warranted.
A full periodontal chart is included within the $1,600 initial phase of periodontal treatment. It is valued at $150, and that figure describes its value rather than an additional fee. It is not an add-on and it is not billed separately.
All of these figures assume no health-fund contribution. A fund may contribute depending on the policy and its limits, and a written quotation is provided before treatment begins. The full list is on the fees page, and the treatment itself is described under deep cleaning.
When does a referral to a specialist happen?
Not at a pocket depth. This is worth stating plainly, because the assumption that a particular number triggers a referral is common and wrong.
Referral is considered after roughly twelve months without stabilisation, or sooner if the disease is clearly progressing despite treatment. If a tooth becomes loose, the clinician assesses it and refers as required, and genuinely extreme cases are referred straight away.
Berala Dental is a general dental practice with no specialist on site. Dentists and oral health therapists are trained to treat most cases of periodontal disease, and refer when a case genuinely needs specialist care. What a specialist does, and when one is the right choice, is covered in do you need a periodontist.
Quick answers
Does charting hurt?
Inflamed sites can feel tender and may bleed, while healthy sites usually feel like light pressure. Tell the clinician if anything is uncomfortable, because the pace and technique can be adjusted.
Is a 4mm pocket bad?
It depends entirely on context: whether it bleeds, whether there is recession, what the X-ray shows and whether it was 3mm last year. That is exactly why a single number is not treated as an answer.
How often should a chart be repeated?
Commonly once a year for someone stable, and more frequently during and after active treatment. The interval is set by what the previous chart showed.
What happens after the chart?
The findings are explained, options are discussed, and any recommended treatment is quoted in writing before it starts. Follow-up intervals are covered in why maintenance is every three months.
Where to go from here
If gums bleed regularly, or a number has been mentioned and never explained, a proper chart is the way to replace guesswork with a record. Related reading: periodontal deep cleaning, do you need a periodontist, the three-month maintenance interval and the fees page.
Understanding your own chart makes every later decision about your gums simpler, and the team is happy to walk through it.
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Written and reviewed by Humzah Aly, Oral Health Therapist. This article is general information only and is not a substitute for personalised dental advice. Please see a dental practitioner to discuss what is right for you.
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