Chairside vs. labside ceramic inlays: effect of temporary restoration and adhesive luting on enamel cracks and marginal integrity

Abstract

Objectives: To assess the influence of different temporary restorations and luting techniques of labside and chairside ceramic inlays on enamel defects and marginal integrity.

Methods: 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.

Results: 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).

Significance: 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.