The short answer
Periodontitis (Parodontitis) develops when bacterial plaque is left undisturbed along the gum line long enough for your immune system to mount a permanent defence — and the bone holding your teeth becomes collateral damage in that defence. The bacteria start the process; your own inflammatory response does most of the destruction. It always begins as ordinary gum inflammation (gingivitis, Zahnfleischentzündung), which is fully reversible, and it becomes periodontitis at the point where the attachment fibres and the bone are involved, which is not. Between those two stages sit weeks or months, not days. Whether you cross that line — and how fast — is decided less by how hard you brush than by smoking, diabetes, genetics and how efficiently your immune system overreacts.
The film that rebuilds itself every few hours
Within minutes of a professional cleaning, a thin protein layer from your saliva settles on the enamel. Bacteria attach to it. Within hours there is a living, organised community on the tooth surface — dental plaque, or more precisely a biofilm (Biofilm). This is not dirt on a surface but a structured colony with its own protective matrix, and that matrix is why rinsing does so little to it.
For the first day or two the film is thin, loosely attached and mostly harmless. Left alone, it thickens and matures, and the deeper layers run out of oxygen — which suits a considerably less friendly set of bacteria, because the species associated with gum disease thrive exactly where oxygen does not reach. Within a few days, minerals from saliva harden parts of the film into tartar (Zahnstein), which no toothbrush removes and which gives fresh plaque a rough surface to grip.
So the honest picture is a daily race. You disrupt the film; it rebuilds. Miss the same spot repeatedly — the inside of the lower front teeth, the far side of the last molar, the gaps between teeth — and that spot matures while everywhere else stays young and harmless. Periodontitis is rarely a whole-mouth failure; it is a handful of sites where the film was never disturbed.
Stage one: your gums get inflamed, and it is meant to be reversible
The first response is gingivitis. The gum margin reddens, swells slightly and bleeds when touched — typically when brushing or using an interdental brush. This is your immune system doing its job: blood vessels widen, defence cells flood the area, and the tissue becomes fragile enough to bleed at the slightest pressure.
Two things about this stage matter most.
Firstly, gingivitis is completely reversible. Remove the film properly for one to two weeks and the tissue returns to normal. Nothing is lost. German dental associations describe the removal of the biofilm as the decisive factor at this stage, and everything else — rinses, gels, special toothpastes — as supporting cast.
Secondly, bleeding is the signal, not the problem. Many people react to bleeding gums by brushing that area more gently, which leaves more film in place and increases the inflammation. The area that bleeds is the area that needs cleaning most — the mechanics of that specific symptom are covered in Why do my gums bleed? Causes, warning signs and what helps (EN).
Stage two: the line that turns inflammation into disease
Gingivitis does not automatically become periodontitis. In many people it comes and goes for years. The transition happens when the inflammation stops being confined to the gum margin and reaches the structures underneath — the periodontal ligament fibres that anchor the tooth root, and the alveolar bone that holds the socket.
At that moment two mechanical changes occur:
- The gum detaches slightly from the tooth, and the natural groove around the tooth deepens into a pocket (Zahnfleischtasche).
- The bone level begins to recede, because the inflammatory process activates the cells that break bone down faster than the cells that rebuild it.
The pocket is the turning point. A healthy groove is one to three millimetres deep and you can clean it at home. A pocket of five or six millimetres is beyond any toothbrush, floss or interdental brush, and no mouthwash penetrates a mature biofilm. So it becomes a sheltered space where anaerobic bacteria are safe from both your hygiene and, largely, your immune system. Deeper pocket, better shelter, more inflammation, deeper pocket — a loop that runs quietly and does not switch itself off.
1Bone loss2Loss of attachment (loss of hold)
Why your own immune system does most of the damage
This is the part that surprises people, and it explains almost everything else about the disease. The bacteria in a periodontal pocket do not, for the most part, eat bone. What they do is provoke. Your immune system responds with inflammatory messengers and enzymes designed to destroy invading organisms. Those same enzymes cannot distinguish perfectly between bacterial targets and your own connective tissue. In a short, sharp infection that trade-off is worth it. In an infection that never resolves because the biofilm sits in a place you cannot reach, the defence runs for years — and the tissue it damages is yours.
That is why the intensity of someone’s immune response matters as much as the amount of plaque. Two people with identical brushing habits can end up in entirely different places: one with mild gum inflammation at fifty, the other with loose teeth at forty. It is also why the disease is usually painless. Chronic inflammation of this kind does not generate the sharp pain signals that toothache does, so the body gives you almost no warning that anything is being lost.
What tips the balance
Plaque is necessary for periodontitis to develop. It is rarely sufficient on its own. The following factors decide whether the process starts, how fast it moves and how well it responds to treatment.
| Factor | What it changes | Can you influence it? |
|---|---|---|
| Smoking | Constricts the small blood vessels in the gum, suppresses the local immune response and slows healing. Smokers often bleed less, which hides the disease until it is advanced. | Yes — and stopping measurably improves treatment outcomes |
| Diabetes (poorly controlled) | Raised blood sugar amplifies the inflammatory response and impairs tissue repair. The relationship runs both ways: gum inflammation also makes blood sugar harder to control. | Partly — through blood sugar control |
| Genetics | Influences how strongly your immune system reacts. A family history of early tooth loss is a genuine signal. | No — but it changes how closely you should be monitored |
| Stress | Alters immune regulation and tends to push oral hygiene down the priority list. | Partly |
| Hormonal phases | Pregnancy, puberty and some contraceptives increase the gum’s reaction to the same amount of plaque. | No — but it can be managed |
| Tartar and overhanging fillings | Create rough, uncleanable surfaces that hold biofilm at the gum margin. | Yes — mechanically removable |
| Mouth breathing, dry mouth | Less saliva means less natural rinsing; many medications cause it. | Often, with support |
| Grinding (Bruxismus) | Does not cause periodontitis, but heavy loading on a tooth that has lost bone support accelerates loosening. | Yes — a night guard (Knirscherschiene) helps |
Two entries deserve emphasis. Smoking is the strongest modifiable risk factor for periodontitis — the consistent message from German and international dental bodies alike. And the link with diabetes runs both ways, which is why your dentist may ask about your HbA1c and your diabetologist about your gums.
"But I brush twice a day"
This is the most frequent objection in the treatment room, and it is a fair one. A toothbrush cleans the outer, inner and chewing surfaces. It does not clean between the teeth — and the spaces between teeth are precisely where periodontitis usually begins. Crowding, crown edges and older fillings add further niches a brush physically cannot enter, and a strongly reacting immune system means an amount of plaque another person tolerates is enough to keep your tissue inflamed. Brushing is necessary and not always sufficient.
What is normal — and when to book an appointment
The measurement itself is quick and undramatic: a blunt probe with millimetre markings, walked around each tooth. It is the only way to know whether you have gingivitis or periodontitis, because the two look similar from the outside.
If you are new to Germany
Gum disease is one of the areas where the German system works genuinely well — and where the process is unlike anything you will have met in the UK or the US.
Periodontitis therapy is a statutory benefit (Kassenleistung), but it does not start on the day of diagnosis. Your dentist first records the findings, then draws up a treatment plan and submits it to your health insurance fund for approval. Only after the fund approves does active treatment begin. The plan then runs in stages — an initial phase of instruction and cleaning, the treatment of the pockets themselves, a re-assessment a few months later, and a structured programme of supportive periodontal care (unterstützende Parodontitistherapie, UPT) that continues over the following two years. Those aftercare appointments are part of the approved benefit, not an optional extra, and skipping them is the most common reason a good result quietly unravels. The coverage rules in detail are set out in Does statutory health insurance pay for periodontitis treatment? (EN).
The practical consequence for you: this is a treatment made of many appointments over two years, so being able to discuss it properly matters more than it would for a single filling. English is one of our working languages — see English-Speaking Dentist in NRW. Patients travel to us from across NRW, and for expats living in Düsseldorf, Cologne or Bonn a journey of 20 to 30 minutes to a practice where the whole conversation happens in English is entirely normal.
There is no fixed timetable, and it is not a matter of days. Continuous inflammation over months to years is what allows the process to reach the bone, and in many people it never gets that far. What shortens the timeline is a combination of undisturbed plaque in specific sites plus a risk factor such as smoking or poorly controlled diabetes.
Yes. The disease begins below the gum line, and the visible parts of the teeth can look immaculate while pockets are deepening between and behind them. Straight, white teeth say nothing about the bone that holds them. This is exactly why pocket depths are measured rather than estimated by eye.
The bacteria involved can transfer between people through saliva — sharing cutlery, kissing — and are commonly found in partners and family members. But transferring the bacteria is not the same as developing the disease: that also requires undisturbed biofilm and a susceptible host. Partners of patients with advanced periodontitis are sensibly advised to have their own gums checked.
Stress does not create the biofilm, so it cannot cause periodontitis on its own. It influences immune regulation and, more prosaically, tends to reduce how carefully people clean between their teeth during difficult periods — an accelerator rather than a cause.
Not usefully, and not as a substitute. The reliable way to stop the immune response is to remove what it is reacting to — the biofilm, including the part inside the pocket that you cannot reach. Adjuncts exist, and ozone therapy is one supportive option we offer alongside the mechanical cleaning, but nothing replaces the removal of the biofilm itself.
Periodontitis is not bad luck and it is not poor character. It is a chain: a film forms, the film matures where it is never disturbed, the gum becomes inflamed, the inflammation reaches the fibres and bone, and a pocket forms that you can no longer clean at home. Every link in that chain except the last one can be broken by you. The last one needs a practice — and once it is broken there, the maintenance appointments are what keep it broken. If you take one thing from this article, make it this: bleeding gums are the early warning, and they are worth acting on while the process is still fully reversible.
Zahnarztpraxis Tsypin · Wuppertal. This article was medically reviewed and is provided for information; it does not replace an examination. Updated August 2026.
