Repair Bond Strength of Self-Cure Bulk-Fill Composites: Influence of Substrate Composition, Surface Conditioning, and Repair Material Type.

Authors

Esra Yildirim-Manav, Sema Yazici-Akbiyik, Sedanur Sakalli, Simge Canatan-Keskin, Sıla Nur Usta

Published in

Journal of esthetic and restorative dentistry : official publication of the American Academy of Esthetic Dentistry ... [et al.]. Jul 27, 2026. Epub Jul 27, 2026.

Abstract

This in vitro study aimed to evaluate the effects of substrate composition, surface conditioning protocol, and repair material type on the repair shear bond strength (SBS) of an aged self-cure bulk-fill resin composite.
A total of 80 specimens were fabricated using two substrate compositions of a self-cure bulk-fill composite (Stela; Automix and Capsule). After initial aging by thermocycling, specimens were repaired according to a 2 × 2 × 2 factorial design based on surface conditioning (mechanical roughening with or without 37% phosphoric acid etching) and repair material type (self-cure composite with proprietary primer or light-cure nanohybrid composite with a universal adhesive). SBS was measured using a universal testing machine. Failure modes were analyzed using a stereomicroscope. Data were analyzed using three-way ANOVA, Tukey's HSD, and Fisher's exact tests (p < 0.05).
Substrate composition, surface conditioning protocol, and repair material type each significantly affected repair bond strength (p < 0.001). Capsule-based substrates showed higher SBS values than Automix substrates. Phosphoric acid etching significantly increased SBS compared with mechanical roughening alone. Repairs performed with the same self-cure composite exhibited significantly higher SBS than those repaired with a light-cure composite. Significant two-way interactions were observed between substrate composition × repair material type (p < 0.001) and surface conditioning × repair material type (p = 0.015). The highest SBS was observed in the Capsule + acid etching + self-cure repair group. Failure mode analysis revealed predominantly cohesive or mixed failures in self-cure repair groups, whereas light-cure repair groups showed a higher frequency of adhesive failures.
Repair bond strength of a self-cure bulk-fill composite is highly material- and protocol-dependent. Utilizing a chemically compatible self-cure material system combined with adjunctive phosphoric acid etching significantly optimizes repair longevity, especially when applied to mechanically triturated capsule-based substrates.
The selection of repair material and surface conditioning protocol significantly influences the repair bond strength of aged self-cure bulk-fill composites. When the original restorative material is known, repair with the same composite system following phosphoric acid conditioning may provide more durable bonding.

PMID:
42504695
Bibliographic data and abstract were imported from PubMed on 27 Jul 2026.

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