It may be the last major taboo in interpersonal interaction: bad breath. Paradoxically, it is often not those affected who notice the problem—our sense of smell quickly adapts to our own stimuli—but rather the social environment. The result is often a shame-driven withdrawal.
Bad breath is not a question of “fault”, but usually a clear medical symptom with a biological cause. As dental professionals, we would like to help you tackle the problem at its root. The first step is the correct diagnosis: where does the odour really come from?
The “nose test”: the medical distinction
In technical terminology, we differentiate very precisely which route the exhaled air is affected. This gives us the decisive clue to the cause.
1. Foetor ex ore (the local origin)
This is by far the most common form (approx. 90% of cases).
- The symptom: The odour is only noticeable when you exhale through the mouth or speak. If you exhale through your nose with your mouth closed, there is no smell.
- The cause: The problem is local in the oral cavity or the throat (more on this below).
2. Halitosis (the systemic origin)
This form is significantly rarer (approx. 10% of cases).
- The symptom: The odour is also noticeable when you exhale through the nose with your mouth closed.
- The cause: Because the exhaled air comes from the lungs and the sinuses, the causes here are often in the ENT area (chronic sinusitis), in the airways, or rarely in the metabolism. Note: The stomach, which is often suspected, is extremely rarely the cause.
The biochemistry of the odour: what is actually happening?
Let us focus on the most common case, foetor ex ore. Billions of microorganisms live in our mouths—an entirely normal ecosystem. Among these inhabitants are specialised bacteria (anaerobes) that live without oxygen. They process proteins from food residues, saliva or dead cells. This decomposition process produces gases known as volatile sulphur compounds (VSC). Put simply: it is precisely these sulphur compounds that create the unpleasant odour.
The bacteria’s hiding places
For these bacteria to become active, they need niches where they are protected from oxygen and the toothbrush. The most common “odour factories” are:
- The tongue: The back third of the tongue in particular is heavily fissured and difficult to clean. This is where 60–80% of the bacteria responsible are often found.
- Periodontal pockets: With periodontitis (inflammation of the supporting structures of the teeth), deep pockets form that you cannot clean at home.
- Leaky margins: Overhanging crown margins or old fillings provide perfect niches for putrefaction processes.
- Dentures: The rough underside of dental prostheses is an ideal surface for biofilm to adhere to.
Saliva: your natural mouthwash
Your saliva is far more than just water. It is rich in oxygen and enzymes that inhibit bacterial growth and neutralise sulphur compounds. If saliva production decreases, bacteria have an easy time of it. This also explains the typical “morning breath”: at night, saliva production drops to almost zero. Caution with dry mouth (xerostomia): Certain medications (e.g. for high blood pressure or depression), stress or drinking too little can lead to persistent bad breath because the natural rinsing function is missing.
Our conclusion
Bad breath is almost always a local, oral problem—and therefore treatable. You do not have to accept it or cover it up with peppermint sweets. A precise diagnosis in our halitosis consultation clarifies whether it is foetor ex ore or halitosis, and which treatment will give you lasting fresh breath.
We will be happy to advise you personally at our dental practice.