On the durability of zirconia-reinforced lithium silicate and lithium disilicate dental ceramics under severe contact

Zirconia-reinforced lithium silicates (ZLS) are a novel generation of aesthetic, lithium-based ceramics intended for use in dental restorations at high loads due to their enhanced fracture strength compared to the previous lithium disilicate (LS2) materials. However, under severe dental conditions, material durability in service may be limited by wear from repetitive, frictional contacts. Here, a comparison is made between commercial ZLS and LS2 dental ceramics of their severe wear behavior under sliding contact against hard zirconia antagonists by means of in-vitro pin-on-disk tests. Specific wear rates greater than 10−6 mm3/N⋅m are obtained. The mechanisms responsible for material removal are a combination of deformation and fracture. Results are discussed in terms of the materials’ microstructure and mechanical properties. In combination with analytical modelling, ZLS dental ceramics are estimated to be up to 5 times less durable than LS2 under conditions modelling heavy chewing/bruxism. Finally, implications for the microstructural design of novel lithium silicate/disilicate materials with improved durability are considered. •Wear tests on lithium-based dental materials are conducted with a view to assessing durability under severe chewing conditions.•Wear behavior depends on material microstructure and mechanical properties. Results are analyzed using contact mechanics.•Zirconia-reinforced lithium silicate is estimated to be 5x less durable than lithium disilicate under severe conditions.•Implications for the microstructural design of novel lithium-based dental materials with improved durability are discussed.