What Is Tooth Decay? — Causes and Early Detection

Tooth decay (caries) is the most common dental disease worldwide — and yet almost entirely preventable. To truly understand caries, it helps to look at how it develops step by step: our mouth harbours billions of bacteria, including cariogenic organisms such as Streptococcus mutans. These bacteria metabolise sugars and carbohydrates from our food and in doing so produce organic acids. These acids attack the mineral structure of the tooth enamel — a process known as demineralisation.

The key is the balance between demineralisation and remineralisation: our saliva contains calcium, phosphate and fluoride and can rebuild the attacked enamel during rest periods. If this balance is chronically disrupted by frequent sugar consumption, poor oral hygiene or insufficient fluoride, the breakdown wins — and caries develops.

The critical factor is time: the longer bacteria and acids can act undisturbed on the enamel, the deeper the decay penetrates. This is why early detection is so crucial. Caries in its earliest stage — so-called initial caries — is still reversible and can be treated without drilling. If one waits until the tooth hurts, the damage is often already considerable.

At our dental practice in Munich-Oberföhring we rely on modern diagnostic methods that detect caries long before it becomes visible to the naked eye: intraoral camera, digital X-ray with 90% less radiation, and DIAGNOdent laser fluorescence. This is how we protect your tooth substance — because the best tooth is one that never needs treatment. Book your check-up appointment now on 089 95760618.

Caries is not a sudden disease but a creeping process that develops over months to years. Understanding the four stages is the key to making the right treatment decision — and to appreciating why every dental visit counts.

Stage 1: Initial Caries (White Spot)

In the first stage, demineralisation has begun, but the enamel is still intact. The affected area appears as a dull whitish spot (white spot) — barely noticeable to the layperson, but clearly visible to an experienced dentist with modern tools. The crucial point: Stage 1 is reversible. With professional fluoride application, Icon infiltration (a resin-based method without drilling) and improved oral hygiene, the enamel can remineralise and the caries stops completely. No drilling, no filling — just targeted prevention.

Stage 2: Enamel Caries

Once the decay has penetrated the enamel, we speak of enamel caries. The patient usually feels nothing at this point — pain only arises when the decay reaches the underlying dentine layer. Treatment is, however, already invasive: the decayed tissue must be removed in a minimally invasive manner and the cavity sealed with a small composite filling (tooth-coloured resin material). The procedure is brief, painless under local anaesthesia, and the prognosis is very good.

Stage 3: Dentine Caries

In the third stage the decay has reached the dentine — the softer, more sensitive layer beneath the enamel. Dentine conducts thermal and mechanical stimuli more readily, so patients now frequently report sensitivity to sweet, cold or hot foods. Depending on the extent of the cavity, a larger direct filling or a laboratory-fabricated ceramic inlay is the appropriate solution. Ceramic inlays offer advantages in durability, marginal precision and aesthetics for large defects in the molar region. The prognosis remains good if treatment is not delayed further.

Stage 4: Pulpitis

When the decay has reached the pulp — the nerve and vascular tissue inside the tooth — we speak of pulpitis. The patient often suffers from spontaneous, severe toothache that can also occur at night. A simple filling is no longer sufficient: a root canal treatment is now necessary to save the tooth. Despite the more extensive procedure, the tooth can be preserved in most cases — but the effort, cost and treatment duration are considerably greater than in the early stages.

The key message: Every stage detected and treated earlier means less loss of tooth substance, simpler treatment, lower costs and a better long-term prognosis. Waiting is costly — in every sense.

Caries treatment does not have to be intimidating. With modern anaesthesia, gentle techniques and an experienced team, the procedure is completely comfortable for most patients. Here is exactly what happens at our practice, step by step:

1. Anaesthesia: Before anything is done to the tooth, it is completely numbed. We use articaine — one of the most effective and well-tolerated local anaesthetics in dentistry. Patients with dental anxiety are welcome to ask us about additional relaxation options; conscious sedation or nitrous oxide treatment can also be arranged by prior agreement. You decide how relaxed your treatment experience should be.
2. Minimally invasive caries removal: Using fine rotary instruments and, in certain cases, ultrasound or airflow, only the decayed, bacterially infected tissue is removed. Healthy tooth substance is preserved — minimally invasive treatment is not a marketing term for us but a lived treatment philosophy. The smaller the amount of tooth substance removed, the more stable and durable the tooth will be in the long term.
3. Cavity preparation: The resulting cavity is cleaned, shaped and prepared to receive the filling material. For composite fillings, the dentine surface is conditioned with a primer to ensure a durable chemical bond — the so-called adhesive technique.
4. Filling and restoration: The composite is placed into the cavity in layers, with each layer cured using an LED polymerisation lamp. This layering technique reduces shrinkage stress and ensures optimal material properties. For larger defects, we discuss at this stage whether a ceramic inlay is the better long-term solution.
5. Check and polish: After curing we check the bite with articulating paper — no high point, no pressure sensation. The filling is finely polished until it integrates seamlessly into the natural tooth surface. At the end you leave our practice with a reconstructed, fully functional tooth — and a good feeling.

Do you have questions about the treatment or would you like advice beforehand? Call us on 089 95760618 or conveniently book an appointment online.

Which filling material is right for you? The answer depends on the size of the defect, the position of the tooth, your aesthetic preferences and your budget. The table below provides an objective overview:

Note on EU amalgam regulations: The European Union has progressively restricted the use of dental amalgam. From 2025, amalgam is largely banned in the EU; exceptions exist only in medically justified individual cases. Amalgam fillings will therefore no longer be an option — tooth-coloured alternatives such as composite and ceramic inlays are the future of dental restorations.

In our consultation we recommend the material that best suits your situation clinically, aesthetically and economically — no standard solutions, no over-treatment.

The most effective caries treatment is the one that never becomes necessary. Prevention is more than good advice — it is a proven system. Here are the building blocks of effective caries prevention:

Fluoride — the most important protective factor: Fluoride hardens tooth enamel and inhibits the metabolism of cariogenic bacteria. Brushing twice daily with a fluoride toothpaste (1,000–1,450 ppm for adults) is the foundation. In addition, we offer professional fluoride varnishes at the practice that are applied in concentrated form directly to the tooth surfaces, significantly enhancing protection.

Fissure sealants: The deep grooves (fissures) on the chewing surfaces of the back teeth are difficult to clean and highly susceptible to decay. Professional sealing of these fissures with a resin varnish reliably protects against caries — particularly in children and adolescents. The GKV covers the costs for permanent posterior teeth in children aged 6 to 17 years.

Diet — reducing sugar: What matters is not the quantity of sugar but the frequency. Frequent intake of sugar and fermentable carbohydrates throughout the day keeps the pH level in the mouth chronically low and leaves the saliva no time for remineralisation. Water and unsweetened teas as drinks, no snacks with sweet foods in between — this is often enough to significantly reduce caries risk.

Brushing technique: Brush teeth twice daily for at least two minutes — systematically, not too hard, with a soft toothbrush. The modified Bass technique is particularly effective at cleaning along the gum line, where caries and periodontitis originate. Electric toothbrushes can improve cleaning performance when used correctly.

Interdental cleaning: The toothbrush hardly reaches between the teeth. Dental floss or interdental brushes should be used daily — they remove the biofilm that causes approximal caries in those areas.

Professional dental cleaning: Every 6 to 12 months we recommend a professional dental cleaning at our practice. The PZR (professional teeth cleaning) removes mineralised deposits (tartar) and subgingival build-up that home care cannot reach — and it gives us the opportunity to monitor your dental status regularly and detect caries at an early stage.