In the current age of adhesive dentistry or microdentistry, conservation of tooth structure is paramount. Rather than using extension for prevention as a treatment guideline, emphasis now is placed on restriction with conviction. The marginal integrity of tooth and restoration interface is dependent upon several factors,including the type of restorative materials, their physical properties, interactions between the materials, physical properties of tissue interface and interaction with oral environment.The relationship between marginal leakage in restoration & type of restorative materials used has been extensively studied both in clinical & laboratory experiments. In the absence of definitive clinical data, laboratory microleakage studies are a well accepted method of screening adhesive restorative materials for marginal seal. The purpose of this, in vitro study, is to compare the sealing ability of the most innovative restorative materials being used in clinical practice; including Conventional Glass Ionomer Cements, Resin Modified GIC, Microfilled Composites, Packable Composites, Nanofilled Composites and Compomer.