Effects of lining materials on the composite resins shrinkage stresses.

Recently, three types of lining materials have been used in dental clinics, conventional powder-liquid glass ionomer cement, light-cured powder-liquid glass ionomer cement and a light-cured single paste type. This study compared the effects of these lining materials on the shrinkage stress of light-cured composite resins during the early setting stage, when polymerization shrinkage occurs. After the second irradiation, the shrinkage stress of composite resins lined with light-cured powder-liquid type cements was approximately 1.0 to 2.2 MPa when the lining application was 1.5 mm and 0.5 mm thick, respectively, demonstrating that a thicker lining application decreased shrinkage stress. The single paste type was only slightly effective in reducing shrinkage stress in composite resins. Although the sample lined with conventional powder-liquid type showed that stresses were less affected by the thickness of the lining, and had the lowest shrinkage stress of all conditions tested, greater exfoliation from the composite resin or the cavity occurred compared to that occurring with other materials.