Relationship between Polymerization Shrinkage of Matrix-Monomers and Marginal Leakage of Composite Resins

The purpose of the present investigation was to clarify the relationship between polymerization shrinkage of the matrix-monomer of the composite resins and marginal leakage. Eight matrix-monomers differing in polymerization shrinkage (2.7 to 11.4%) were experimentally prepared. Experimental composite resins were made from these monomers filling with 0.2μm spherical silica particles with a constant volume of 54.5 percent. Standardized Class V cavities were prepared on the labial surface of freshly extracted bovine teeth. Before placement of each restoration, the cavities were conditioned and primed with an experimentally prepared bonding agent in which consisted of the Bis-GMA-TGDMA system.The marginal leakage was evaluated by the scores depending on the depth of the dye penetration. As a result, an S-shaped curve of correlation showed a clear transition at the point of 7 percent of the polymerization shrinkage of the matrix-monomer.