Influence of compliance of the substrate materials on polymerization contraction stress in thin resin composite layers.

The present study determined in a laboratory set-up the influence of compliance of the substrate material on polymerisation contraction stress for various thicknesses of bonded dental resin composite films. When the compliance of the tensilometer set-up was increased from 0.029 micron MPa-1 to 0.150 micron MPa-1, the contraction stress in films with a thickness of 100 microns and a diameter of 5.35 mm decreased from 22 to 7 MPa. For the 700 microns samples the stress decreased from 12 to 11 MPa. It was concluded that if compliance from the substrate materials is possible, a thinner resin composite film may effect a more reliable bond.