To assess the influence of different temporary restorations and luting techniques of labside and chairside ceramic inlays on enamel defects and marginal integrity.
120 extracted human third molars received MOD preparations with one proximal box each limited in either enamel or dentin. 64 Cerec 2 inlays and 56 IPS Empress I inlays were randomly assigned to the following groups (fabrication mode: chairside (CS)=no temporary restoration (TR), labside (LS)=TR with Luxatemp (L) inserted with TempBond NE, or Systemp.inlay (SI) without temporary cement), luting technique: SV=Syntac/Variolink II, RX=RelyX Unicem: A: Cerec inlays were luted with (1) CS/SV. (2) CS/SV/Heliobond separately light-cured. (3) CS/RX. (4) LS/L/SV. (5) LS/L/RX. (6) LS/SI/SV. (7) LS/SI/RX. (8) LS/SI/RX with selective enamel etching. B: Empress. (9) L/SV. (10) L/SV/Heliobond separately light-cured. (11) L/RX. (12) SI/SV. (13) SI/SV, Heliobond separately lightcured. (14) SI/RX. (15) SI/RX after selective enamel etching. Before and after thermomechanical loading (TML: loading time of TR 1000×50N+25 thermocycles (TC) between +5°C and +55°C; clinical simulation: 100,000×50N+2500 TC) luting gaps, enamel cracks, and marginal adaptation to enamel and dentin were determined under an SEM microscope (200×) using replicas.
Loading time of temporary restorations negatively affected enamel integrity and enamel chipping (p<0.05). Luxatemp resulted in less enamel cracks than Systemp.inlay (p<0.05). Syntac/Variolink achieved better marginal enamel quality than RelyX Unicem in all groups (p<0.05). Marginal quality in dentin revealed no differences when no temporary cement was used (p>0.05). Temporary cement negatively affected dentin margins when RelyX Unicem was used (p<0.05).
Chairside-fabricated Cerec inlays reduce the risk of enamel cracks and marginal enamel chipping due to omitted temporary restorations. Syntac/Variolink revealed a significantly better performance than RelyX Unicem.