Fracture strength of flowable bulk-fill resin composites from different dental manufacturers for occluso-proximal...

To investigate the fracture strength of occluso-proximal restorations in primary teeth using different commercial brands of flowable bulk-fill resin composites (as an intermediate layer or entire restoration) in comparison with conventional resin composite (incremental technique).

Two standardized occluso-proximal cavities (4 mm cervico-occlusal height, 4 mm bucco-lingual/palatal width and 2 mm disto-mesial width) were prepared in 90 sound primary molars. The teeth were randomly divided into nine groups (n=10) according to the resin composites (Z350 XT, Filtek Bulk-Fill Flowable, Beautifil II, Beautifil Bulk Flowable, Opallis, Opus Bulk Fill Plus), number of increments of flowable bulk-fill resin composite [2 mm (intermediate layer) or 4 mm (entire restoration)] and control - conventional resin composite (incremental technique). All restored teeth were subjected to pH cycling prior to fracture strength test. The mean fracture strength values were analyzed using one-way ANOVA and Tukey's post-hoc tests. (α= 5%). The failure mode of each specimen was categorized as adhesive, cohesive, or mixed and analyzed descriptively.

No significant difference in fracture strength was found among the groups (P= 1.00). Mixed failures prevailed (range of 60-90%) in all groups.

Based on fracture strength data, contemporary flowable bulk-fill resin composites that have high filler content may be an option for restoring entire conservative occluso-proximal cavities in primary molars, regardless of the commercial brand, promoting the simplification of restorative procedures in pediatric dental practice.