Evaluation of Microleakage in Posterior Nanocomposite Restorations with Adhesive Liners

Microleakage is the clinically detectable passage of bacteria, fluids, molecules or ions between a cavity wall and the restorative materials applied to it. This study was conducted to evaluate and compare the microleakage in Class II nanocomposite restorations, with resin-modified glass ionomer liner (group I), nanofilled flowable composite liner (group II)&without liner (group III). Thirty six non carious upper premolar teeth extracted for orthodontic purposes were selected. Standard class II cavities were prepared. The teeth were then randomly&equally divided into three groups with 12 teeth in each group. The teeth were subjected to thermocycling. After that apex of each tooth was sealed with acrylic resin and the teeth were painted with two coats of nail varnish, except for the area of 2mmfrom the periphery of the restorations. The coated teeth were immersed in buffered (pH 7) 0.5% methylene blue dye for 48 hours.Teeth were sectioned& observed under stereomicroscope of 10X magnification. At gingival level, Group I exhibited slightly lesser microleakage than group II but was not statistically significant. Group I showed no significant difference between microleakage at occlusal and gingival level (Z=1.732; P=0.083). However, in Group II and Group III, there was significantly greater microleakage at the gingival level (Z= 2.162 and 3.162; P= 0.002 and 0.002, respectively). Both resin-modified glass ionomer and flowable composite can be used as liners under nano composite restorations as reduction in microleakage was comparable.