Gum Pocket Depth Chart: What the Numbers on a Perio Chart Mean
Key takeaways
- Healthy gum pocket depth is 1–3 mm with no bleeding.
- 4 mm is a warning sign, 5 mm and above usually indicates periodontitis, and 6 mm or more is considered a deep pocket.
- Pocket depth alone doesn’t show bone and attachment loss – you need the gingival margin and CAL too.
- On a perio chart, each tooth has six readings: three on the facial side and three on the lingual side.
What is a gum pocket?
Between the tooth and the gum there is a small space called the gingival sulcus. In health it is shallow. When plaque and inflammation break down the attachment between gum and tooth, the space deepens into a periodontal pocket. Pocket (probing) depth is measured with a periodontal probe from the gingival margin (the edge of the gum) to the base of the sulcus or pocket, in millimeters.
Gum pocket depth chart: what the numbers mean
| Probing depth | What it usually means | Typical next step |
|---|---|---|
| 1–3 mm, no bleeding | Healthy sulcus | Routine preventive care |
| 1–3 mm with bleeding | Gingivitis (inflammation without attachment loss) | Improved home care, professional cleaning, re-evaluate |
| 4 mm | Early warning: inflammation, a pseudo-pocket, or early periodontitis | Check bleeding and CAL; monitor closely |
| 5 mm | Usually periodontitis, especially with bleeding or attachment loss | Periodontal diagnosis and treatment planning |
| 6 mm or more | Deep pocket; typically moderate to severe periodontitis | Active periodontal therapy; possible specialist referral |
These ranges are general guidance. A diagnosis always combines probing depth with bleeding, clinical attachment level, radiographs, and the patient’s history. For the formal framework, see our periodontal staging and grading chart.
Is a 4 mm pocket bad?
Not necessarily, but it deserves attention. A 4 mm reading can be a pseudo-pocket – swollen gum tissue that makes the pocket look deeper without any loss of attachment – or the first sign of periodontitis. Bleeding at that site and the position of the gum relative to the cementoenamel junction (CEJ) tell you which it is.
What about 5 mm and 6 mm pockets?
At 5 mm, plaque and calculus become hard to remove with a toothbrush and floss alone, and bacteria can keep the pocket inflamed. Pockets of 6 mm or more are one of the complexity factors that can place a case in Stage III periodontitis. They usually need active periodontal therapy and closer follow-up.
Why pocket depth isn’t the whole story
Pocket depth is measured from the gum line, and the gum line moves. If the gums recede, the pocket can look shallow even though bone and attachment have been lost. If the gums are swollen, the pocket can look deep even though attachment is intact. That’s why the chart also records the gingival margin and calculates clinical attachment level (CAL):
- Gum margin below the CEJ (recession): CAL = probing depth + recession.
- Gum margin above the CEJ (swelling or overgrowth): CAL = probing depth − the distance from margin to CEJ.
- Gum margin at the CEJ: CAL = probing depth.
Example: a 3 mm pocket with 3 mm of recession means 6 mm of attachment loss – far more serious than the “3” suggests. We cover this in detail in perio chart measurements explained.
How to read the numbers on a perio chart
- Find the tooth. Most US charts use the Universal Numbering System, teeth 1–32, starting with the upper right third molar.
- Read six numbers per tooth. Three facial readings (distal, middle, mesial) and three lingual or palatal readings. Each is the deepest point at that site.
- Look for red marks or dots. These usually indicate bleeding on probing; other symbols may mark suppuration (pus) or plaque.
- Check the gingival margin row. Positive or negative values show where the gum sits relative to the CEJ.
- Look at the totals. Many charts summarize the percentage of bleeding sites and the number of sites at 4 mm, 5 mm and 6 mm or more.
- Compare with the last chart. A pocket that went from 3 mm to 5 mm is more significant than a stable 5 mm pocket.
Want to practice? Try our free online perio chart – enter readings and it calculates CAL, bleeding percentage, and the number of deep sites for you.
Capture every pocket depth without putting down the probe
With Denti.AI Voice Perio, hygienists speak pocket depths, bleeding, recession, furcation and mobility as they probe, and the perio chart fills in on screen. A full-mouth chart takes about 5 minutes, saves straight to your practice management system, and comes with a patient-friendly oral health report. Voice Perio is part of OneStop Clinical, together with Denti.AI Scribe for AI clinical notes.
How often should pocket depths be measured?
A full-mouth periodontal chart is generally recorded at the initial comprehensive exam, then repeated at intervals based on the patient’s periodontal status and risk – commonly at least once a year, and more often for patients in periodontal therapy or maintenance. Many practices chart more often than this because comparing charts over time is the most reliable way to see whether disease is stable or progressing. Follow your practice protocol and current ADA and AAP guidance.
Frequently asked questions
What is a normal gum pocket depth?
A healthy gum pocket (sulcus) is 1–3 mm deep and doesn’t bleed when probed.
Is a 4 mm gum pocket bad?
A 4 mm pocket is a warning sign rather than a diagnosis. It can be a pseudo-pocket caused by swollen tissue or an early sign of periodontitis. Bleeding and clinical attachment level at that site show which it is.
What does a 5 or 6 mm pocket mean?
Pockets of 5 mm usually indicate periodontitis, especially with bleeding or attachment loss. Pockets of 6 mm or more are considered deep, typically indicate moderate to severe periodontitis, and are a complexity factor for Stage III periodontitis.
Why are there six numbers for each tooth on a perio chart?
Each tooth is probed at six sites – three on the facial side (distal, middle, mesial) and three on the lingual or palatal side – and the deepest reading at each site is recorded.
Can gum pockets get shallower?
Yes. With treatment and good home care, inflammation resolves and pockets often become shallower. Comparing charts over time is how clinicians track this.
