Jyothi
Class II cavities were prepared in 120 intact maxillary premolars, The buccolingual extension of the cavities will be 4
mm and the gingival wall will be located in dentin/cementum (2 mm below the cementum-enamel junction/CEJ);
the internal angles will be rounded and cavosurface margins will be finished with gingival margin trimmer. The
samples were divided into four groups (n = 60), according to the material used; smart dentine replacement (SDR),
SonicFill, X Tra Fill and Z350 XT, restored to a depth of 4 mm. Following thermocycling, samples were sectioned
buccolingually and examined under a stereomicroscope. Seven samples from each group were coated with nail
varnish except for approximately 1 mm around the tooth restoration junction. These samples were examined under
stereomicroscope after staining with 2% buffered methylene blue dye. The remaining samples were examined under a
scanning electron microscope for gap formation. The data were statistically analyzed using one-way ANOVA and posthoc
Bonferroni test.