Bleeding when you floss is not normal, and it is not a sign you flossed too hard. It is the earliest visible sign of an inflammatory response to bacterial plaque. Caught at that stage it reverses completely in a couple of weeks. Left alone it does not.
The two stages, and the line between them
Gingivitis is inflammation of the gum tissue only. Red, puffy, bleeds on brushing or flossing. No bone has been lost. Remove the plaque and biofilm consistently and the tissue returns to normal. This is fully reversible.
Periodontitis is what happens when that inflammation extends below the gum line and the body begins resorbing the bone that anchors the tooth. Bone does not grow back on its own. Treatment can halt the process and in some cases regenerate a small amount surgically, but the baseline you are defending is the bone you have today. That is the whole reason the distinction matters.
The numbers your hygienist calls out
The string of numbers read aloud during a cleaning is probing depth in millimetres at six points around each tooth, measuring the pocket between gum and tooth.
| Depth | Meaning |
|---|---|
| 1 to 3 mm, no bleeding | Healthy |
| 1 to 3 mm with bleeding | Gingivitis |
| 4 to 5 mm | Early periodontitis, usually treated with scaling and root planing |
| 6 mm and above | Moderate to advanced, often referred to a periodontist |
A pocket deeper than about 4 mm cannot be cleaned by a toothbrush, which is the mechanical reason the disease becomes self-sustaining past that point. The National Institute of Dental and Craniofacial Research keeps a plain-language summary of the disease process and current treatment, and it is the best single starting page on the topic.
Risk factors that actually move the needle
- Smoking and vaping. The single largest modifiable risk factor, and it also suppresses bleeding, which masks the disease while it progresses.
- Diabetes. The relationship runs both directions: poor glycaemic control worsens periodontitis, and periodontitis worsens glycaemic control. The CDC's oral health prevention material covers this link and the population-level picture.
- Genetics. A meaningful share of aggressive cases run in families. It is not an excuse, but it does mean some people need three-month recalls rather than six.
- Dry mouth from medication. Saliva is a defence mechanism; hundreds of common drugs reduce it.
What reverses gingivitis: brushing twice daily with fluoride toothpaste, cleaning between the teeth once daily with floss or interdental brushes, and a professional cleaning to remove the calcified deposits you cannot reach. Two weeks of consistency is usually enough to stop the bleeding.
What treatment looks like past that point
Scaling and root planing, sometimes called a deep cleaning, removes deposits from the root surface below the gum line, usually under local anesthetic and often across two visits. It is followed by a periodontal maintenance schedule, typically every three to four months rather than six, because the pocket repopulates with bacteria faster than healthy tissue does. Surgical options, including flap surgery and grafting, come into play when pockets stay deep after non-surgical treatment.
One thing to be clear about: if a practice recommends a deep cleaning on all four quadrants at a first visit with no probing chart shown to you, ask to see the numbers. There should be a recorded chart. If there is not, get a second opinion. Our directory lists periodontists by city if you want an independent read.
Why it matters beyond your mouth
Periodontitis is associated with cardiovascular disease, poorly controlled diabetes, and adverse pregnancy outcomes. Association is not proof of causation and the research is still arguing about mechanism, but the consistency of the association across large populations is why physicians increasingly ask about gum health. MedlinePlus maintains a readable summary of the current evidence with links to the underlying studies.