Alexander came in with a broken old filling on his lower molar. The tooth was vital, the nerve intact, but the damage covered nearly half the chewing surface. A standard filling in this situation would last 3-5 years before chipping again. A crown would be excessive: the tooth was still structurally sound. Between a filling and a crown, there is an intermediate solution that is often the ideal choice.
An inlay fills the cavity within the cusps of the tooth. An onlay covers one or more cusps. Both are fabricated in a dental laboratory from an individual impression and bonded to the tooth with special adhesive cement.
Why ceramic, not composite?
A direct composite filling is shaped right in the mouth. This is quick, but the material has limitations: it shrinks during curing, absorbs stains over time, and loses its shape under chewing forces.
A ceramic inlay is made outside the mouth, either in a dental lab or using a CAD/CAM system (CEREC). It precisely replicates the tooth anatomy, does not shrink, and maintains its colour throughout its lifespan. The average lifespan of a ceramic inlay is 10-15 years, and with good hygiene it can last even longer.
Inlay, onlay, or crown?
Inlay: suitable when the defect is limited to the area between the cusps.
Onlay: needed when one or more cusps are damaged, but the tooth walls remain intact.
Crown: necessary when the tooth is more than 60-70% destroyed or the nerve has been removed.
How the procedure works
The treatment requires two appointments. At the first, the dentist removes the damaged tissue, shapes the cavity, and takes an impression (traditional or digital). A temporary filling is placed.
After 5-10 days the inlay is ready. At the second appointment the dentist checks the fit, colour, and bite, then bonds it with adhesive cement. The bonding process takes about 30 minutes.
If the practice has a CEREC system, both steps can be completed in a single visit: scanning, milling, and bonding on the same day.
Insurance coverage in Germany
The GKV (statutory health insurance) covers standard treatment: an amalgam filling or a composite filling for front teeth. Ceramic inlays are considered a Privatleistung (private service). The GKV pays a fixed subsidy (Festzuschuss) equal to the cost of an amalgam filling, and the patient covers the difference.
A good Zahnzusatzversicherung can reimburse 70-90% of the inlay/onlay cost. If you have many molars with large fillings, the insurance often pays for itself after just one inlay.