Stages of tooth decay: white spot, enamel, dentine, root

Decay is not a yes-or-no matter. It goes through several stages, and treatment looks different at each one: from toothpaste and fluoridation to a filling, then to root canals and a crown. The gap in cost between the first and the last stage is more than tenfold — and the gap in time between them is often less than a year. Here is how the stages differ, what the dentist does at each, and why a small painless cavity is the best moment to come rather than a reason to wait.

Four stages, and only the first needs no drill

Decay destroys a tooth layer by layer, following the density of the tissue. First minerals leave the enamel, then the enamel collapses, then the process moves into dentine — the softer tissue underneath — and finally reaches the pulp, the nerve.

• White-spot stage — the enamel has lost minerals but is still intact. No cavity yet. Treated without drilling.
• Enamel decay — a defect confined to the enamel. Minimal preparation and a small filling.
• Moderate decay — the process has entered the dentine. This is what most people arrive with.
• Deep decay — only a thin layer of dentine separates it from the nerve. Next comes pulpitis and root canal treatment.

The key line runs between the first stage and all the rest. At the white-spot stage enamel can still be re-mineralised and the tooth stays whole. Once the enamel has collapsed, the tissue does not grow back — it can only be replaced with a filling.

The white spot: decay that can still be reversed

This is a matt white or chalky patch on the enamel, most often near the gum or between teeth. It does not hurt and a probe does not catch on it, so people almost never notice it themselves. The dentist finds it during an examination, sometimes with a dye or by drying the surface: demineralised enamel turns noticeably whiter than healthy enamel when dry.

At this stage the tooth is not drilled. The enamel is saturated with minerals and strengthened with fluoride. At the same time the cause is addressed: how the person brushes, whether plaque collects in that area, how often they snack. Without that the spot comes back in the same place.

Fluoridation is a separate procedure and is not included in the price of hygiene. Worth knowing in advance so the figure at reception is not a surprise.

The other half of the work is removing the plaque under which the spot appeared. That is why an appointment like this almost always goes together with professional hygiene: while the biofilm is in place, remineralisation works worse.

Enamel decay and superficial decay

The spot has collapsed and a defect has formed, still within the enamel. The tooth may react briefly to sweet or cold and settle immediately. Many people put this down to sensitivity and keep waiting.

Treatment now requires preparation, but a minimal one: the dentist removes the affected enamel and places a small restoration. Working under a microscope makes a real difference here — the exact border of affected tissue is visible, so healthy enamel is not cut away «just in case».

Decay between teeth is a separate case. You cannot see it in a mirror and often not even on examination: the contact surface is covered by the neighbouring tooth. It is found on an X-ray, which is exactly why a check-up every six months makes sense even when everything looks fine.

Moderate and deep decay: when a filling is needed

The process has entered the dentine, which is softer than enamel and breaks down faster. So a cavity behind a small hole in the enamel often turns out to be far larger than it looks from outside. Hence the familiar complaint: «it was a pinhole and the dentist took away half the tooth» — in reality the tooth was already hollow inside.

Symptoms appear: reaction to cold, sweet or sour, food packing, sometimes a bad smell from one specific spot. The pain is still brief and stops as soon as the trigger is removed.

Treatment is a filling-restoration: anaesthesia, isolation with a rubber dam, removal of affected tissue, layered rebuilding of the shape and polishing. At Houston restorative work is done under a microscope.

Deep decay adds a risk: only a thin layer of dentine remains above the pulp, and the dentist cannot always say in advance whether the nerve will hold. Sometimes the tooth is treated in two visits with a temporary filling, to give the pulp time to respond. If the nerve does not hold, that is pulpitis and root canal treatment.

Root decay: why it appears in adults

The root of a tooth has no enamel — it is covered by cementum, a much softer tissue. While the root sits under the gum it is protected. But with age, and especially with periodontitis, the gums recede and expose the neck of the tooth.

From there things move faster than on the crown: cementum and dentine break down more easily than enamel, and the area next to the gum is harder to clean. Root decay is therefore almost always a companion to a gum problem rather than a story of its own.

It is also harder to treat: the cavity sits close to the gum and is difficult to isolate from moisture, and no composite bonds properly without a dry field. Sometimes the gums have to be treated before the restoration.

What helps in advance: if you notice bleeding gums or feel that your teeth have «got longer», that is a reason to come before decay appears.

Decay under a filling and under a crown

Secondary decay develops at the border between an old restoration and the tooth. The reason is not that «the filling was bad» — over the years any bond fatigues, a microscopic gap appears and bacteria get in.

The catch is that everything looks intact from above. The filling is in place, nothing falls out, and the tissue underneath is breaking down. Such decay is found on an X-ray, or when the filling suddenly sinks or part of the tooth chips off.

The same happens under a crown: if the margin is not tight, decay spreads along the stump unnoticed. That is why every check-up includes inspecting old work, not only looking for new holes.

What it costs at each stage

The clearest argument for coming early is not medical but arithmetical.

• Consultation with examination and a plan — UAH 690.
• White-spot stage — remineralisation and fluoridation, no preparation. The cheapest and quickest stage.
• Superficial, moderate and deep decay — a filling-restoration from UAH 2,350; the exact figure depends on the size of the cavity and how many surfaces have to be rebuilt.
• Cosmetic restoration of a front tooth — from UAH 6,800: shade matching and layered work.
• Pulpitis — root canal treatment from UAH 7,100, plus rebuilding the crown part and often a crown from UAH 7,200.

The difference between the first and the last item is more than tenfold — with possibly less than a year between them.

Frequently asked questions

Dmytro Kobozev

Head doctor · endodontist

Chief doctor at Houston clinic. Restorative dentistry and endodontics under a microscope, treatment of canals, cysts and granulomas, cosmetic restoration.

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