New generation bulk-fill resin composites: Effects on mechanical strength and fracture reliability.

Purpose: To investigate the mechanical performance and fracture reliability of new generation, bulk-fill resin composites of different viscosities.

Methods: Forty sound maxillary premolars were prepared into Class I cavities comprised of 5 mm width × 5 mm length × 5 mm thickness. The teeth were randomly allocated into four groups (n = 10) according to the restorative material: Negative control - without restoration; Positive control - conventional resin composite (Opallis; FGM) was applied using increments of up to 2.