The short answer
Inlays are among the longer-lived restorations in dentistry: ceramic and gold inlays that are well made, well bonded and well looked after commonly serve for many years, and frequently for more than a decade. But a lifespan is not a property you buy with the material — it is the result of six or seven variables, and only two of them belong to the laboratory. The bond quality on the day, the amount of healthy tooth left around it, your bite, your cleaning between the teeth and your risk of new decay decide far more than whether the block was lithium disilicate or a gold alloy. That is why the same restoration can fail in three years in one mouth and still be sound after fifteen in another. On average across long-term studies, ceramic inlays and onlays show survival of roughly 92–95 % after five years and about 91 % after ten; cast gold inlays are reported at around 96 % after ten years and 87 % after twenty. For comparison, a direct composite filling in a back tooth has a median service life of about eleven years. As a rule, read all of those as averages across study populations rather than a prediction for one tooth — oral hygiene, the chewing load and how much sound tooth remains around the restoration shift the individual outcome in both directions.
What actually ends an inlay's life
Restorations rarely die of old age. They are ended by one of a handful of specific events, and knowing which ones they are tells you exactly where to spend your attention.
New decay at the margin. This is the most common ending by a distance. The inlay itself does not decay — the tooth next to it does, at the join, usually on the surface between two teeth where a brush never reaches. Everything you do with floss or an interdental brush is aimed at this one failure mode.
A fracture in the ceramic. Uncommon, but it happens: a thin section, an unsupported edge, a bite that loads the restoration unevenly, or years of grinding. Sometimes a small chip can be smoothed and left; sometimes the inlay is remade.
A fracture in the tooth. The restoration survives and a wall of the tooth gives way beside it. This is the failure mode that argues for covering weakened cusps rather than filling around them — and it is why a heavily undermined tooth is often better served by an onlay from the start.
Debonding. The inlay comes out intact. Almost always this points back to the bonding appointment — moisture in the field, a contaminated surface — and it is one reason a dry field and, where the margin is critical, work under a microscope are not fussiness but insurance.
The nerve, later. A tooth that has been drilled several times over its lifetime can eventually need root canal treatment (Wurzelbehandlung), through no fault of the inlay. Depending on where the access is made, the restoration may survive the procedure or may need replacing afterwards.
The cement joint wearing at the edge. A slow process rather than an event: over years, the thin line of cement at the margin can wear or roughen, which gives plaque somewhere to sit and starts the first failure mode above.
The factors you can influence — in order of how much they matter
1. How you clean between your teeth. Not how hard you brush. The margin of an inlay between two molars is cleaned by floss, an interdental brush or a water flosser, and by nothing else. Daily use of one of them is the single most effective thing you can do for the lifespan of any restoration.
2. Your bite. An inlay that carries more load than the teeth around it is under permanent stress. Grinding (Bruxismus) multiplies that, and it usually happens at night, when you cannot notice it. A night guard (Knirscherschiene) for people who grind is not an accessory; it is the difference between a restoration that survives and one that chips.
3. Your risk of new decay. Frequency of sugar matters more than quantity — five sweetened coffees across a working day are harder on a margin than one dessert. Dry mouth is a bigger risk factor than most patients realise: several common medications reduce saliva, and saliva is what neutralises acid and remineralises enamel.
4. Acids. Germany runs on sparkling water, apple spritzer and citrus, and all of them are mildly acidic. None of it is forbidden. But sipping something acidic over two hours at a desk is a different exposure from drinking it with a meal, and over years that pattern shows at restoration margins.
5. Your check-up rhythm. A margin that is beginning to fail can often be polished, sealed or repaired if it is caught early, and needs a full remake if it is caught late. That is the whole argument for regular examinations and professional cleaning (professionelle Zahnreinigung, PZR) at intervals that match your risk, not a fixed number for everyone.
6. The quality of the day it was fitted. Preparation, isolation, bonding protocol, occlusion check. You cannot influence this after the fact — which is why it is worth asking about beforehand.
7. The material and the laboratory work. Real, but last on the list. A gold inlay tolerates deformation better; ceramic tolerates compression well and bending less well. Both are capable of long service. Our comparison of the two goes into detail: Ceramic inlay or gold inlay? (EN).
The signs that an inlay is ageing
Most restorations announce their decline quietly, months before anything hurts. These are the signals worth acting on.
The distinction matters financially as much as clinically. Caught early, a failing margin is often a small intervention. Left for a year, the same tooth may have moved a rung up the ladder — from inlay to partial crown, or from partial crown to crown.
What happens when an inlay does fail
Nothing about this stage is dramatic, and it helps to know the options in advance.
A small chip is often polished smooth and monitored. Not every imperfection needs replacing.
A debonded but intact inlay can sometimes be re-bonded, provided the fit is still perfect and both surfaces can be properly conditioned. Keep the piece and bring it with you — do not attempt to glue it back yourself, and never use household adhesive.
Decay at the margin is treated according to how far it has gone: a localised repair where the damage is small and accessible, a new restoration where it is not.
A fractured cusp normally means moving up to an onlay or a partial crown, because what failed was the tooth, not the restoration.
A remake is the honest answer in a proportion of cases, and it is worth asking two questions when it comes up: why did this one fail, and what will be different next time? A remake that repeats the same conditions tends to repeat the same outcome.
Warranty, insurance and who pays for the second attempt
In Germany, dentures (Zahnersatz) carry a statutory two-year warranty period — and in our practice you have a two-year warranty on dentures made in our own master dental laboratory. Because an inlay is classified under fillings rather than dentures, the arrangements can differ, so ask at the planning appointment what applies to your specific restoration and have the answer noted in writing. That is a fair question and any practice should welcome it.
Two further points. Supplementary dental insurance (Zahnzusatzversicherung) typically reimburses a tariff-dependent share of privately paid treatment depending on the tariff, but policies limit how often the same tooth may be re-treated — worth reading before you need it. And your statutory fund’s contribution towards an inlay is tied to the standard filling on that tooth, whatever number of restorations that tooth has had: the mechanics are set out here: Does health insurance pay for inlays in Germany? (EN).
Does an inlay outlast a filling?
As a rule, yes — particularly in larger cavities, where a direct filling has to carry stresses it was never ideally suited to. That is the main clinical argument for paying the difference at all.
But the comparison is only fair like for like. A small composite filling in a low-risk mouth can serve for many years and cost you nothing beyond your insurance contribution. An inlay in a mouth with untreated gum disease, nightly grinding and no interdental cleaning will not reach its potential either. Longevity is bought with habits at least as much as with materials — and habits are cheaper.
Situations that shorten the odds
Heavy grinders. Design, bite adjustment and a night guard from the start. If you already wake with tight jaw muscles or a dull headache, mention it before planning rather than after a chip.
Dry mouth. Whether from medication, radiotherapy or a medical condition, reduced saliva raises the risk at every margin in your mouth. It changes both what we recommend and how often we want to see you.
Smokers. Smoking affects the gum around the margin and, through gum health, the long-term seal.
Untreated gum disease. A restoration in a mouth with active periodontitis (Parodontitis) is a good restoration in a bad neighbourhood. Treat the gums first — that sequence is not upselling, it is the order that makes the restorative work last.
People who move countries. This one is specific to our patients. If you are likely to leave Germany in a few years, ask for a copy of your X-rays, your findings and your invoices before you go. A new dentist abroad who can see what was done and when will make better decisions than one guessing at a shape in an X-ray.
It is not impossible, but nobody can promise it and you should be sceptical of anyone who does. What is realistic: a well-made, well-maintained inlay is a long-term restoration, and many are still in service after ten years and more. What ends most of them is not wear but new decay at the margin — which is largely in your hands.
Both are durable, with different strengths. Gold deforms slightly rather than fracturing and is kind to the opposing tooth, which is why it retains a following among heavy grinders. Ceramic matches the tooth in appearance and is colour-stable. In most mouths the difference in lifespan is smaller than the difference made by cleaning and bite.
Not usually, but do not leave it. The exposed tooth surface is unprotected and can become sensitive, and neighbouring teeth start drifting into the space surprisingly quickly. Keep the inlay in a clean container, avoid chewing on that side and book an appointment in the next days — sometimes it can be re-bonded.
It is the most effective maintenance available. A cleaning reaches the margins between the teeth where an inlay is most vulnerable, and the person doing it will spot a rough edge or an early gap while it is still small. How often depends on your gums and your decay risk rather than on a rule.
Ceramic itself is colour-stable and does not stain the way a large composite filling can. What can change is the tooth around it, which may darken slightly with age — so a mismatch after many years usually says more about the natural tooth than about the ceramic.
There is, and it is worth acknowledging. Every cycle removes a little more substance, and eventually the sensible answer is a crown, or in some cases a different plan altogether. That is a reason to break the cycle — cleaning, bite, decay risk — rather than a reason to fear the next appointment.
How long an inlay lasts is decided less on the day it is made than on the thousands of ordinary days afterwards. The material matters, the bonding matters a great deal, and then the whole question moves into your bathroom: what you do between the teeth, whether your bite is protected at night, how often the margins are checked by someone who knows what an early gap looks like.
Treat the join between inlay and tooth as the place that decides everything, and you will be doing precisely what the evidence would tell you to do.
Zahnarztpraxis Tsypin · Wuppertal. This article was medically reviewed and is provided for information; it does not replace an examination. Updated August 2026.
