The short answer
For a small or medium cavity, a well-placed composite filling (Füllung) is the sensible choice and there is nothing second-rate about it. An inlay (Inlay) becomes the better option when the cavity is large, when the walls of the tooth are thin, when the damage runs deep between the teeth, or when the tooth has already been repaired several times. The decision is not about which material is “nicer” — it is about how much healthy tooth is left to work with and how much force that tooth has to take. Statutory health insurance (gesetzliche Krankenversicherung, GKV) covers the filling and not the inlay, so you are also choosing whether a private top-up is worth it for this particular tooth.
What you are actually choosing between
A filling is built directly in your mouth: soft composite placed in layers, hardened with a light, shaped by hand. An inlay is made outside the mouth from ceramic or a gold alloy and then bonded into the prepared cavity — which is why it usually needs two appointments and a temporary (Provisorium) in between. The step-by-step version of that process is in How a dental inlay is fitted — the appointments step by step (EN).
Everything below is about which of the two your particular tooth needs.
The five things that actually decide
1. How much tooth is left standing
This is the single biggest factor. A filling is held by the tooth around it; the more tooth wall there is, the better it works. Once a cavity spreads across the chewing surface and down between the teeth, the remaining walls become thin and unsupported — and a large block of composite inside a weakened tooth does not reinforce it the way people assume.
A rough rule from the chair: if the cavity is narrow and the cusps are solid, a filling. If the cavity is wide, the walls are thin and you can see light through them, the case for a laboratory-made restoration grows.
2. Where the cavity ends
A cavity that stops on the visible chewing surface is easy to fill well. A cavity that runs down between the teeth and finishes at or below the gum line is a different job entirely: the dentist has to rebuild a wall, a contact point and a margin in a space that is wet, tight and hard to see.
That is precisely the situation in which the indirect route helps — the shape is built on a model, where it can be checked from every angle. It is also the situation in which a hurried filling causes trouble later: an overhanging margin between two molars is a plaque trap that no amount of brushing solves.
3. Whether the tooth has had root canal treatment
A root-treated tooth (after Wurzelbehandlung) has usually lost a lot of substance before treatment even began, and the access cavity removes more. Such teeth are more prone to fracture, and they typically need a restoration that holds the remaining cusps together rather than one that simply plugs the hole. Here the discussion often moves past inlays altogether, towards a partial crown or a crown.
4. What your bite does — particularly at night
If you grind or clench (Bruxismus), the forces on your back teeth are far higher than in ordinary chewing, and they arrive in the wrong direction. That changes the calculation in both directions: heavy grinders can chip ceramic, but they also wear through and fracture large composite fillings. What usually matters more than the material choice is whether the grinding itself is addressed — a night guard (Knirscherschiene) protects whatever restoration you end up with.
Tell your dentist if your partner says you grind, if you wake with tight jaw muscles, or if you have flattened front teeth. It genuinely changes the plan.
5. Your budget, your time and what you will actually maintain
An inlay costs more, takes an extra appointment and requires you to come back. That is not a footnote — a treatment you postpone is worse than a treatment you complete. If the choice is between a good composite filling now and an inlay “sometime next quarter when things calm down”, take the filling.
The reverse is also true. If a tooth has been patched three times in five years and each repair has been slightly bigger than the last, spending once on a restoration built to last is usually the more economical decision.
Side by side
| Composite filling | Laboratory inlay | |
|---|---|---|
| Appointments | One | Usually two, with a temporary in between |
| Made | In the mouth, layer by layer | Outside the mouth, on a model |
| Best suited to | Small and medium cavities with solid walls | Large cavities, thin walls, deep interdental damage |
| Shaping the contact point | Freehand, in a tight wet space | On the bench, checked before fitting |
| Material | Tooth-coloured composite | Ceramic or gold alloy |
| Paid by GKV | Yes, as standard care | No — the fund pays only the filling-level amount |
| What you sign | Nothing extra in standard cases | A written additional-cost agreement (Mehrkostenvereinbarung) |
| Repairable | Yes, often directly | Small repairs possible; larger failures usually mean remaking |
When a filling is the right answer
It is worth saying plainly, because patients are sometimes told the opposite: most cavities in Germany are treated with composite fillings, and that is clinically appropriate. A filling is the better choice when:
- the cavity is small or moderate and the surrounding walls are intact
- the tooth is otherwise untouched and you want to preserve the option of doing more later
- the damage is on a front tooth or a visible surface where composite can be layered and blended
- you need the tooth sorted today — one appointment, done
- the tooth is under observation for another reason and the plan may change
A filling done well by an unhurried dentist under a dry field outperforms a compromised inlay every time. The technique matters more than the category.
When an inlay earns what it costs
The case for an inlay is strongest when:
- the cavity is wide, the walls are thin, and a direct filling would be mostly filling and very little tooth
- the damage extends deep between the teeth, where building a good contact point freehand is difficult
- previous fillings in the same tooth have repeatedly failed at the margins
- the tooth carries heavy chewing load and needs a hard-wearing, precisely shaped surface
- you want the restoration to be shaped and polished outside the mouth, with the fit checked before it is fixed in place
The option that often gets skipped: the partial crown
Between “filling” and “inlay” there is a third answer that changes the money question completely.
An inlay sits inside the tooth, held by the surrounding walls. A partial crown (Teilkrone) goes a step further and covers over one or more weakened cusps, taking the load off them. When a cusp is cracked or badly undermined, that protection is the whole point — and no inlay, however well made, provides it.
Why it matters financially: in the German system an inlay is classed as a filling, so there is no fixed subsidy (Festzuschuss) for it. A partial crown is classed as denture work (Zahnersatz), which means a treatment and cost plan (Heil- und Kostenplan, HKP), a Festzuschuss from your fund, and a subsidy that rises with your bonus booklet (Bonusheft) — from 60 % of standard care with no stamps, to 70 % after five complete years and 75 % after ten. Two similar-looking restorations, two completely different bills. The detail is in What does an inlay cost in Germany? (EN).
So if your dentist says “this cusp will not survive an inlay”, that is not an upsell. Ask which category the proposed restoration falls into and why — the answer is clinical, and it should be explainable in one sentence.
Questions worth asking before you agree
Take these into the appointment. They are the questions that make the difference between an informed decision and a nod.
1. How much healthy tooth wall is left? Ask to see it on the intraoral camera or the screen. 2. Is any cusp cracked or undermined? If yes, ask whether a partial crown is the more honest option. 3. What would you do if this were your tooth? Dentists answer this question surprisingly directly. 4. If we do a filling now, what is the realistic next step if it fails? A plan with a stated plan B is a good sign. 5. What exactly does my fund pay towards each option? For an inlay, the answer is “the amount of the comparable filling” — and you should get that in writing. 6. Can this tooth be isolated properly? Deep margins below the gum can make a dry field difficult, and that affects which option works.
When the decision can wait — and when it cannot
Delay rarely keeps the choice open. Cavities that are borderline between filling and inlay tend, after a few months, to become clear cases for the more extensive option.
If you have just moved to Germany
Two things routinely surprise new arrivals.
First, the paperwork is the mechanism, not bureaucracy for its own sake. Choosing an inlay over the filling your fund covers means signing an additional-cost agreement (Mehrkostenvereinbarung) beforehand. It states what you pay privately. Signing it after treatment is not how the system works, and a practice that hands it to you afterwards has done it in the wrong order.
Second, you can have this conversation in English. Deciding between a filling, an inlay and a partial crown involves nuance, and nuance is what gets lost in a language you are still learning. We treat patients in English; English-Speaking Dentist in NRW sets out what to look for if you are searching more widely. Patients from Düsseldorf, Cologne or Bonn generally reach us in 20 to 30 minutes — for most expats a normal distance for a dentist they can actually talk to.
No. For a small cavity in an otherwise healthy tooth, an inlay means removing more tooth structure to create the shape the restoration needs — which is the opposite of what you want. The advantage appears with size, not automatically with price.
Often yes, and it is a reasonable strategy for a borderline tooth. Be aware that each replacement removes a little more tooth, so this works best as a considered plan rather than an indefinite loop of repairs.
Your statutory fund pays the amount that the comparable, least expensive filling would have cost, and you pay the difference. Supplementary dental insurance often covers a share on top — check your tariff and any waiting period before treatment starts, not after.
On a back tooth, appearance alone is a weak reason to replace an intact, well-sealing filling. Every replacement removes a little more tooth. If the filling is sound, leaving it in place is usually the more conservative decision.
The clinical limits are ours to explain; the choice within those limits is yours. If two options are genuinely defensible for your tooth, you should hear both, with the reasons, before anyone reaches for a drill.
Ask how much tooth is left, not which material sounds better. Small cavity with solid walls: a filling, done carefully, is the right answer and the one your fund covers. Large cavity, thin walls, damage deep between the teeth, or a tooth that has been repaired repeatedly: an inlay is worth the extra appointment and the extra cost. A cracked or undermined cusp belongs in a third category altogether — and that one comes with a Festzuschuss, which is worth knowing before you sign anything.
Zahnarztpraxis Tsypin · Wuppertal. This article was medically reviewed and is provided for information; it does not replace an examination. Updated August 2026.
