Bad breath is perhaps the last major taboo in social interaction. Paradoxically, those affected often do not notice the problem themselves—our sense of smell quickly adapts to our own body odors—while people around them do. The result is often withdrawal accompanied by shame.
Yet bad breath is not a question of “fault,” but usually a clear medical symptom with a biological cause. As dental professionals, we want to help you address the problem at its source. The first step is an accurate diagnosis: where does the odor actually originate?
The “nose test”: the medical distinction
In clinical terminology, we differentiate precisely how the exhaled air is affected. This distinction provides the crucial clue to the underlying cause.
1. Foetor ex ore (local origin)
This is by far the most common form (approx. 90% of cases).
- Symptom: The odor is noticeable only when you exhale through your mouth or when speaking. If you exhale through your nose with your mouth closed, nothing can be detected.
- Cause: Das Problem liegt lokal in der Mundhöhle oder im Rachenraum (dazu unten mehr).
2. Halitosis (systemic origin)
This form is significantly less common (approx. 10% of cases).
- Symptom: The odor is noticeable even when you exhale through your nose with your mouth closed.
- Cause: Since the exhaled air originates from the lungs and paranasal sinuses, causes are often found in the ENT field (chronic sinusitis), the respiratory tract, or rarely in metabolic disorders. Note: the stomach, which is often suspected, is very rarely the cause.
The biochemistry of odor: what actually happens?
Let us focus on the most common case, foetor ex ore.Billions of microorganisms live in our mouths—a completely normal ecosystem. Among them are specialized bacteria (anaerobes) that thrive in the absence of oxygen. They metabolize proteins from food debris, saliva, or shed cells. During this decomposition process, gases known as volatile sulfur compounds (VSCs) are produced.Simply put: these sulfur compounds are responsible for the unpleasant odor.
Where the bacteria hide
For these bacteria to become active, they require niches protected from oxygen and from your toothbrush. The most common “odor factories” are:
- The tongue: Particularly the posterior third of the tongue is highly fissured and difficult to clean. About 60–80% of odor-causing bacteria reside here.
- Periodontal pockets: n periodontitis (inflammation of the supporting structures of the teeth), deep pockets form that cannot be cleaned at home.
- Defective margins: Overhanging crown margins or old fillings provide ideal niches for decomposition processes.
- Dentures: The rough underside of dental prostheses is an ideal surface for biofilm adhesion.
Saliva: your natural mouthwash
Saliva is far more than just water. It is rich in oxygen and enzymes that inhibit bacterial growth and neutralize sulfur compounds. When saliva production decreases, bacteria gain the upper hand. This also explains typical “morning breath”: during the night, saliva production drops almost to zero. Be cautious with dry mouth (xerostomia): certain medications (e.g., for hypertension or depression), stress, or insufficient fluid intake can lead to persistent bad breath because the natural cleansing function is reduced.
Our conclusion
Bad breath is almost always a local, oral problem—and therefore treatable. You do not have to accept it or mask it with mints. A precise diagnosis in our halitosis consultation determines whether it is foetor ex ore. or Halitosis and which therapy will provide you with lasting fresh breath.
We are happy to advise you personally in our dental practice..