Fatigue Resistance and Crack Propensity of Novel "Super-Closed" Sandwich Composite Resin Restorations in Large MOD Defects
To asses the influence of conventional glass ionomer cement (GIC) vs resin-modified GIC (RMGIC) as a base material for novel, super-closed sandwich restorations (SCSR) and its effect on shrinkage-induced crack propensity and in vitro accelerated fatigue resistance. A standard MOD slot-type tooth preparation was applied to 30 extracted maxillary molars. A modified sandwich restoration was used, in which the enamel/dentin bonding agent was applied first, followed by a Ketac Molar or Fuji II LC base, leaving 2mm for composite resin material. Shrinkage induced enamel cracks were tracked with photography and transillumination. Samples were loaded until fracture or to a maximum of 185,000 cycles under isometric chewing, starting with a load of 200 N and gradually up to a maximum of 30,000 each...