The short answer
Applied locally in the mouth, ozone therapy (Ozontherapie) is considered a low-risk supportive measure. The gas is directed at one tooth, one gum pocket or one small area of soft tissue for a very short time, and it decomposes again into ordinary oxygen. The side effects patients report are mild and short-lived: a metallic taste, a dry feeling, brief sensitivity in the treated tooth. The real technical safety issue is not the tooth but the airway — ozone should not be inhaled, which is why it is applied through a sealing applicator with suction running. And the biggest risk of all is a decision rather than a substance: using ozone instead of the filling, the cleaning or the periodontal treatment a tooth actually needs. Ozone is an adjunct. It is also a private service, and the statutory health insurance (gesetzliche Krankenversicherung, GKV) does not pay for it.
What ozone actually is, and why the question comes up at all
Ozone is oxygen with a third atom attached. That third atom is loosely held, which makes the molecule reactive: it breaks down readily, and in doing so oxidises what it touches. On a tooth surface or in a pocket, that action reduces the bacteria, fungal cells and viral particles present — and within a short time the gas has fallen apart into ordinary oxygen.
Most people’s mental image of ozone comes from somewhere else: summer smog warnings, the ozone hole, air purifiers with a bad reputation. That is why safety is usually the first thing patients ask about. It is a fair question, but the comparison does not hold. A smog alert describes a population breathing a diluted gas for hours. Dental ozone means a metered amount held against a few square millimetres of tooth or gum for seconds, with suction running beside it.
Where the actual risk sits: the airway, not the tooth
Ozone is a respiratory irritant. Breathed in over time, it irritates the lining of the nose, throat and lungs — that is well established, and it is exactly why the delivery method in dentistry matters more than the substance itself.
In practice, the containment is the treatment protocol:
- A sealing applicator. A soft cup or a fine tip sits against the tooth or slides into the pocket or root canal, so the gas goes where it is aimed.
- Suction. High-volume suction stays in the mouth throughout, so escaping gas is drawn away rather than rising past your nose.
- A short, metered dose. The device delivers a defined amount for a defined, brief period. It is not left running.
- Nose breathing. You keep breathing normally through your nose. That is not a comfort instruction, it is part of the protocol.
Handled that way, throat irritation and coughing are unusual. If you notice a sharp smell or start to cough, say so — the application stops in a second, and the gas dissipates by itself.
The side effects that are actually reported
Because the exposure is brief and local, the list is short and unglamorous — which is the point.
- Taste and smell. A sharp, slightly metallic note during the application and for a minute or two after. It fades.
- A dry feeling. Oxidising gas dries what it touches. Some people notice a dry patch of gum or lip for an hour or so.
- Short-term tooth sensitivity. On an exposed tooth neck or in a deep cavity, the tooth can be briefly cold-sensitive, usually settling within a day or two.
- Mild gum irritation. A pale or slightly tender patch where the applicator sat, generally recovering within a day.
- Throat or airway irritation. Uncommon with a sealed local application, more likely where containment slips.
Nothing on that list needs treatment, and nothing on it should still be there a week later.
The contraindication lists — and where they come from
Search for ozone contraindications and you will find long, alarming lists: glucose-6-phosphate dehydrogenase deficiency (favism), untreated hyperthyroidism, a recent heart attack, clotting disorders, pregnancy. Almost nobody explains where those lists come from.
They come from systemic medical ozone therapy — ozone introduced into the body as a whole, most often by treating a quantity of the patient’s own blood and returning it (Eigenbluttherapie). Different dose, different route, different risk profile. It is not what happens when a dentist puts an applicator on a molar: local dental ozone is a surface application, acting where it is placed and then breaking down rather than circulating in your bloodstream. The systemic list does not transfer one-to-one to a tooth.
That does not make your medical history irrelevant. We still ask — and you should still tell us — about:
- Pregnancy. There is no evidence of harm from a brief local application, but little research in pregnancy either. Out of caution, elective add-ons are often postponed to the second trimester or until after the birth. Nothing urgent is postponed.
- Asthma, COPD or a very reactive airway. Not an automatic exclusion, but tell us beforehand — including about inhalers and about attacks triggered by cold air or strong smells.
- A known reaction to ozone. Genuine hypersensitivity is rare, but if you have ever reacted to ozone in a medical setting, that settles it.
- Systemic ozone therapy you are already having elsewhere, so nothing is duplicated unknowingly.
- Children. Local ozone is generally well tolerated by children, precisely because it needs no injection — but it stays a decision taken with the parents, never a silent extra.
The risk that matters most: treating ozone as a replacement
This is the part of the subject where honesty is worth more than enthusiasm.
Ozone reduces germs on the surface it reaches. It does not remove anything. It does not dissolve the sticky bacterial film (Biofilm) that has organised itself on a tooth, it does not lift off tartar (Zahnstein), it does not remove softened, decayed dentine, and it does not rebuild lost bone. A tooth that needs a filling still needs a filling after an ozone application. A mouth that needs periodontal treatment (Parodontitis-Behandlung) still needs it. A patient overdue for a professional cleaning (professionelle Zahnreinigung, PZR) is not cleaned by a gas.
The evidence position is best stated plainly: studies on dental ozone are mostly small, use varied protocols and devices, and follow patients for short periods. Reviews of that work tend to land in the same place — promising as a supportive measure, not strong enough to replace established treatment. German professional dental bodies treat it the same way: an adjunct alongside conventional care, not a therapy in its own right. Anyone who tells you ozone alone will reverse advanced decay or cure gum disease has left what is known behind.
So the honest ranking is this: the substance is a small risk, the delivery a manageable one, and the expectation is the big one. Postponing real treatment because something gentler was offered instead is how a small problem becomes an expensive one.
What is normal afterwards — and when to contact us
Outside our opening hours, the out-of-hours dental service (zahnärztlicher Notdienst) covers acute problems — swelling with fever, breathing difficulty or severe pain should never wait for the next working day.
If you have just moved to Germany, or your German is limited
Ozone therapy is not standard practice everywhere, and its scope is described differently from country to country. If you have come from the UK, the US or India, you may never have been offered it — or may have been offered something with the same name and a very different remit.
Two things are worth knowing. In Germany you are entitled to understand what you are agreeing to before treatment starts, including what a supportive measure is not expected to achieve. And you can have that conversation in English: questions about risk are the last ones you should have to translate under pressure in the chair. English-Speaking Dentist in NRW sets out how appointments, plans and paperwork run here in English.
Because ozone is private, you will also see it costed separately. It is charged under the fee schedule for dentists (GOZ) — meaning the amount belongs on an estimate you see beforehand, not on an invoice afterwards. If you are unsure what you are approving, ask for it line by line. That is a normal request here.
A brief whiff during a sealed application is unlikely to cause more than a momentary throat tickle or a cough. Ozone is an airway irritant, so the whole protocol is built around not inhaling it. If you cough or your throat feels raw, tell us straight away — we stop, and the gas breaks down on its own.
At the concentrations and exposure times used in dentistry, ozone is not known to damage enamel, dentine or standard restorative materials, and it does not corrode titanium implants. It is a reactive gas all the same, so the application stays short and targeted. If you have extensive cosmetic work, mention it beforehand.
Discuss it rather than deciding in advance. A brief local application is a small intervention, but research in pregnancy is thin, so many clinicians postpone elective add-ons — often to the second trimester or until after the birth. Anything urgent is treated regardless: untreated infection is the greater risk in pregnancy.
None has been established for brief local dental use, and the reason is simple: the gas breaks down into oxygen and does not accumulate in the body. The reverse has not been established either — nobody can promise you a long-term benefit. Honestly stated, both the risks and the benefits sit in a modest range.
Ozone in the dental chair is a small, brief, local application, and its risks are correspondingly small provided the gas is contained rather than inhaled. Side effects are mild and short-lived, and the alarming contraindication lists online mostly describe systemic ozone therapy, not what happens on a tooth. Tell us about asthma, pregnancy and any ozone treatment you are having elsewhere, and the rest is routine. The risk worth taking seriously is a mistaken expectation: ozone supports treatment and does not stand in for it.
Zahnarztpraxis Tsypin · Wuppertal. This article was medically reviewed and is provided for information; it does not replace an examination. Updated August 2026.
