Introduction
Ceramic inlays are intracoronal restorations made outside the mouth – in the laboratory or chairside by CAD/CAM – and bonded into the cavity with resin cement. They are the most esthetic and wear-resistant tooth-coloured option for medium to large posterior cavities, but ceramic is brittle: it survives only if the preparation gives it enough bulk and the adhesive cementation is done without error. The inlay preparation rules shared with composite inlays belong to topic 29; this note covers what is specific to ceramics.
Ceramic materials
Inlay ceramics are either glass-ceramics (crystals in a glass matrix – translucent and etchable with hydrofluoric acid) or polycrystalline zirconia (no glass phase – very strong but opaque and not etchable).
Glass-ceramic inlays gain their strength from the bond to the tooth: they are etched, silanised and luted with resin cement – never with zinc phosphate or glass-ionomer cement.
Indications, advantages and disadvantages
Indications and contraindications
- Medium to large Class I and II cavities in premolars and molars, where a direct composite would suffer from shrinkage, poor contacts and wear.
- High esthetic demand, replacement of large amalgam or gold restorations, metal allergy.
- Margins in enamel, supragingival or at the gingiva, where a rubber dam can be placed.
- Bruxism, clenching, heavy occlusal load – fracture.
- Deep subgingival margins – no isolation, no enamel to bond to, poor impression or scan.
- Small cavities (direct composite is better), shallow cavities or short crowns without room for 1.5 mm of ceramic, thin weakened cusps (cover them – onlay); poor hygiene, high caries risk.
Advantages and disadvantages
- Esthetics: enamel-like translucency and colour stability – no staining or ageing as in composite.
- Wear resistance close to enamel; smooth glazed surface with little plaque; biocompatible and chemically inert.
- Polymerisation shrinkage limited to the thin cement layer; contacts and anatomy shaped outside the mouth; the bonded inlay stiffens the remaining cusps.
- Brittle: fractures when thin, notched or loaded before it is bonded.
- Wears opposing teeth – mostly feldspathic porcelain left rough after adjustment.
- Cost, technique-sensitive cementation, two visits and a provisional in the laboratory route; difficult to adjust, repair and remove; resin cement wears at the margins (marginal ditching).