Investiagtion of microleakage in CL II composit resin restorations with two-type of Amalgams in open sandwich technique

the aim of this study was to determine the microleakage at the cervical margin of the class II composite resin syntac with and without a cervical amalgam base and to compare microleakage restoration at the occlusal margins of restorations and inferface of amalgam and composite.68 extracted sound permanent premolar were used.68 class II slot cavities were prepared in these teth.the teeth were randomly divided into four groups,and restored as follows :group A: Amalgam(cinalux)+syntac(bonding agent)+ composit(Tetric)( sandwich technique),groupB :Amalgam(luxalloy)+syntac+composite(tetric)(sandwich technique),group C:yntac +composite (control 1).group D:Amalgam(cinalux)(control2).then the teeth were thermocycled,and immersed in the fuchsion.marginal leakage was assessed by the degree of dye penetration on sections of the restored teeth,under stereo microscope at 7.5 maginification.for analysis of data non parametric statistic tests (Kruskal-wallis and mann withney-u)were used.although marginal leakage was not completely eliminated,sandwich technique exhibited significantly less leakage at the cervical margins than conventional method (syntac/tetric composite) and also there was no significant difference between cinallux and luxalloy amalgams,at the cervical and occlusal margins.