Comparison of polymerization behaviors, microhardness and compressive strength between bulk-fill resin and dual-cured core resin.

OBJECTIVES

This study aimed to investigate the polymerization shrinkage, microhardness, DOC, and compressive strength of composite resin materials employed for core restoration, encompassing dual-cured core resin composites and LC bulk-fill composites.

METHODS

Bulk-fill resin composites [Filtek One Bulk fill (BFO), Bulk Fill Base (BBB), Metafil Bulkfill One (BMF)] and dual-cured core resin composites (Luxacore Z, Any-Core) served as the experimental group, while two conventional LC resin composites [Filtek Z350 (FTZ), metafil flo (FMF)] served as the control group. Two dual-cured core resin composites were named as follows, CLD, CLS (Luxacore Z, in dual-cured mode and self-cured (SC) mode); CAD and CAS (Any-Core, in dual-cured mode and SC mode). Linear polymerization shrinkage, depth of cure (DOC) using microhardness, and compressive strength were evaluated for each experimental group. The results were analyzed using one-way ANOVA, and a post-hoc test (Duncan's test) was performed at a 95% confidence level.

RESULTS

The linear polymerization shrinkage rate was higher in the dual-pol9ymerization core resin group than in the control group FTZ and bulk-fill resin groups, and in each dual-cured core resin, the dual-cured group was higher than the SC group. The DOC was higher in the bulk-fill resin group than in the control group, and the DOC of the dual-cured core resin group showed a significant variation depending on the product. The compressive strength of the bulk-fill resin group showed a significant variation depending on the product. The compressive strength in the bulk-fill resin group was higher as the filler content increased in the dual-cured mode than the SC mode in the dual-cured core resin group.

CONCLUSIONS

Bulk-fill resins showed superior polymerization shrinkage and DOC compared to conventional resin composites and dual-cured core resins. At 4 mm depth, Bulk-fill resin composites achieved an appropriate DOC, but for dual-cured core resins, the DOC varied depending on the product.

CLINICAL SIGNIFICANCE

Highly filled bulk-fill resins could be a predictable restorative material for deep cavities and post-endodontic core material, considering its polymerization shrinkage, DOC, and mechanical properties.