Abstract
When a single bulk-fill resin composite mass is placed in a large occlusal cavity using the conventional bulk filling technique, the surrounding cavity walls around the composite mass act as external restraint, resulting in restrained shrinkage. This paper addresses the diagonal gap in semi-split bulk filling as a crucial key to minimizing external restraint and allowing favorable unrestrained shrinkage in large posterior bulk-fill resin composite restorations. The unrestrained shrinkage results in minimal stress, and prevents internal debonding, marginal gap formation, and cuspal deflection, as well as enamel micro-cracking.
Keywords: Bulk composite; Delayed closure; Diagonal gap; Direct posterior restoration; External restraint; Occlusal cavity; Restrained shrinkage; Segment; Semi-split; Unrestrained shrinkage