Ceramic inlays: what they do better, and where they reach their limits

Think of it as a made-to-measure component rather than a repair paste. The decayed tissue and the old filling are removed, the cavity is shaped so that it has no undercuts and clean, accessible margins, and that shape is recorded — in our practice with a digital scan (Primescan), which means no impression tray and no material setting in your mouth. From the scan a restoration is designed and then either milled from a ceramic block or pressed, finished and polished by a dental technician (Zahntechniker).

The material is not the porcelain of a teacup. Modern dental ceramics — lithium disilicate above all, and hybrid ceramics with a polymer content — are engineered for the forces of chewing. What arrives back at the second appointment is a solid piece of ceramic that fits your cavity and no other.

The last step is the one that decides everything. The inlay is not cemented in the old sense; it is bonded (adhesive Befestigung). The tooth surface is conditioned, the ceramic is treated on its inner surface, and the two are joined by a thin layer of composite cement that is hardened with light. Done well, the join is a single mechanical unit. Done in a wet field, it is the weak point of the whole restoration — which is why the dam, the suction and the unhurried protocol matter more than the brand of ceramic.

1. No setting shrinkage inside the tooth. A direct composite filling is placed as a paste and cured in the cavity, and every composite shrinks slightly as it hardens. Dentists work around this with layering techniques and it works well in small and medium cavities — but the larger the volume, the more the stresses add up. A ceramic inlay is already fully formed when it goes in. Only the thin cement layer sets in place, so the shrinkage forces are a fraction of those in a large direct filling.

2. A proper contact point. The tightness of the contact to the neighbouring tooth decides whether food packs into the gap after every meal and whether floss shreds or glides. Building that contact freehand deep between two molars is one of the more demanding things in restorative dentistry. Building it on a model, with the tooth accessible from every side, is a different task altogether — and it is one of the most noticeable everyday differences patients report.

3. It stabilises the tooth it sits in. Because the ceramic is bonded rather than wedged, forces are distributed across the bonded surface instead of being pushed outward against thin remaining walls. In a heavily filled tooth that is not a cosmetic detail: it is part of the reason a bonded inlay is often chosen instead of the next step up, a full crown (Krone), which requires the whole tooth to be reduced.

4. It behaves like a tooth. Ceramic conducts heat and cold far less readily than metal, so hot coffee and cold water are less of an event. Its surface, when properly polished and glazed, attracts less plaque than a roughened composite. It does not discolour: the shade you approve at the second appointment is broadly the shade you will still see in five years, while a large composite filling tends to pick up a rim of staining over time.

5. Nothing metallic, nothing that shows. There is no mercury question, no grey shimmer through the enamel, no dark line at the neck of the tooth. For patients who react to metals or simply prefer metal-free dentistry, that is a decision in itself — although it is worth saying plainly that gold remains an excellent material, and preferring ceramic is a legitimate choice rather than a correction of a mistake.

6. It preserves more tooth than a crown. This is the advantage that matters most in ten years’ time. An inlay or onlay replaces the missing part and leaves the healthy part alone. A crown, by contrast, is a new outer surface for the whole tooth — sometimes unavoidable, but never reversible. Where an inlay is genuinely sufficient, choosing it keeps the crown in reserve for later.

An article that only lists advantages is a sales page. These are the honest boundaries.

Brittleness under bending. Ceramic tolerates compression well and bending poorly. In patients who grind heavily (Bruxismus), thin ceramic margins and unsupported edges can chip. It does not mean ceramic is ruled out — it means the design has to be chosen for the grinding, the bite has to be adjusted carefully, and a night guard (Knirscherschiene) becomes part of the treatment rather than an optional extra.

It needs a minimum thickness. Ceramic below a certain thickness fractures, so the cavity must be prepared to give the material room. In practice a ceramic inlay therefore removes a little more substance than a direct composite would in the same tooth. For a large defect that is irrelevant, because the substance is already gone. For a small one it is a genuine argument against.

It needs a dry field. Adhesive bonding fails in the presence of saliva, blood or crevicular fluid. When the cavity margin runs deep below the gum, achieving a reliably dry field is difficult, and honesty about that is part of the planning — sometimes the answer is a different design, sometimes a preliminary step to move the margin, sometimes a different restoration entirely.

Repairs are limited. A chipped composite can often be added to in ten minutes. A fractured ceramic inlay can occasionally be polished or repaired, but in many cases the answer is remaking it. That is not a common event, but it is a different risk profile from a direct filling.

Two appointments and a temporary. Between the preparation and the fitting you wear a temporary restoration (Provisorium), and you treat it with a little care. With our own in-house master dental laboratory (Meisterlabor) the interval is short, but it is still an interval.

It costs more, and the statutory system pays little towards it. Your fund treats an inlay as an upgrade to a filling, not as a denture, so the Festzuschuss and the Bonusheft do not apply. The mechanics — and the paperwork you sign — are set out here: Does health insurance pay for inlays in Germany? (EN).

There is no winner in that table, only a fit. A software engineer who grinds through deadlines and wants nothing visible is a different case from a patient who lost a cusp last week and wants the toughest thing available at the lowest cost. The comparison between the two laboratory materials is a topic in its own right: Ceramic inlay or gold inlay? (EN).

Patients tend to research materials, because materials have names and websites. In practice the outcome of a bonded ceramic restoration rests on four things that rarely appear in brochures.

The preparation — smooth, rounded, no sharp internal angles, margins where they can be seen and cleaned. The isolation during bonding, which is why we work with a dry field and, where the margin is critical, under a microscope. The laboratory work, where the contact point and the chewing surface are shaped; having the technician in the same building means a question is answered in a corridor rather than in a courier note. And the occlusion check at the end: an inlay that sits a fraction high is uncomfortable at first and a fracture risk later.

Ask about those four things rather than about ceramic brands, and you will learn more about the quality you are being offered.

Nothing on the second list is dramatic if it is looked at quickly. All of it becomes harder if you spend three months hoping it will settle.

If you grind your teeth. Tell us before planning, not after a chip. Grinding does not exclude ceramic, but it changes the design, the bite adjustment and the aftercare, and a night guard belongs in the plan from day one.

If you play contact sports. A mouthguard protects bonded restorations as much as it protects the teeth.

If you have several old fillings failing at once. Doing all of them in ceramic in one season is rarely the wisest sequence, financially or biologically. Prioritise the teeth that are structurally at risk and treat the rest in the covered way; nobody is obliged to upgrade every tooth.

If your German is limited. Bonding appointments involve a lot of short instructions — bite, hold, open, do not swallow — and following them in a language you are translating in your head is unnecessarily stressful. We work in English every day alongside German, Russian, Turkish, Ukrainian, Arabic, Kurdish and French, and patients travel to us from across the Bergisches Land, Düsseldorf, Cologne and Bonn for exactly that reason: English-Speaking Dentist in NRW.