Adhesion of bulk-fill resin composites as core and intraradicular post materials only versus the use of glass-fiber posts in different regions of root dentin

Abstract

This study assessed adhesion of bulk-fill resin-composites as core and post materials only versus the use of fiber resin composite (FRC) posts. Human teeth (N = 84) were cut at the CEJ and endodontically treated and randomly divided into seven groups: TP: Titanium post (Flat Head T); SFRC: S2-glass FRC (Pinpost); EFRC1: E-glass FRC (GC Everstick) directly bonded; GFRC: E-glass FRC (Glassix Nordin); EFRC2: E-glass FRC (Everstick); BF1: Bulk-fill resin (Surefill SDR); BF2: Bulk-fill resin (SonicFill). Groups TP, SFRC, EFRC and GFRC were cemented (Panavia 21), while other groups were bonded directly to the intraradicular dentin. The core parts were constructed using a resin composite (G-aenial) except for Groups BF1 and BF2. The core-cervical dentin interface was loaded under shear forces. Push-out tests were performed in a Universal Testing Machine (1 mm/min). Data (MPa) were analyzed using two-way ANOVA and Tukey`s tests (α = 0.05). Not the root level (p > 0.05) but the type of core and post material significantly affected shear and push-out bond results (p < 0.001). BF1 (9.2 ± 2.1) and BF2 (9.3 ± 3.1) showed significantly lower bond strength to the cervical dentin (p < 0.05) compared to other groups (11.6 ± 2.5–19 ± 6.8). FRC post types did not show significant difference being higher than those of TP, BF1 and BF2 (0.57 ± 0.37–2.34 ± 1.98) (p > 0.05). Partial cohesive core fracture was more common while BF1 and BF2 showed exclusively adhesive failures. Cohesive failure in the cement was frequent in Group TP (53%) compared to other groups (3–24%). BF1 and BF2 presented exclusively complete adhesive failure of the bulk-fill material.

Keywords:

• Adhesion
• bulk-fill-composite
• dentin
• fiber-reinforced-composite posts
• push-out test
• resin composite

Acknowledgements

The authors are grateful for the assistance of Mr. A. Trottmann and Mrs. B. Sener from University of Zürich, Center for Dental and Oral Medicine (Zürich, Switzerland) with the specimen preparation and microscopical analysis. We also acknowledge Dentsply (Konstanz, Germany) and KaVo Kerr Group (Biberach/Riss, Germany) for generous provision of the bulk-fill resin composites and the applicator.

Disclosure statement

The authors did not have any commercial interest in any of the materials used in this study.