Available online 13 December 2025

Author links open overlay panelTony Lorey a, Jennifer Woolford a, Markus B. Blatz b, Ulrich Lohbauer a, Renan Belli a, José Ignacio Zorzin aShow moreHighlights•

Fracture mechanics-based adhesion testing.

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Adhesion testing of two different universal resin cements and a gold standard adhesive.

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Evaluation of both modes (one-step self-adhesive and multi-step adhesive) using the same testing methodology.

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Adhesion testing was performed at 24 h and after 6 months.

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A comprehensive review of the literature, a detailed description of the experimental approach, and a discussion of the findings.

AbstractObjective

The purpose of this study was to evaluate the adhesion potential of two universal resin cements compared to a gold standard adhesive system, considering application mode and storage time, using a novel method for interfacial fracture toughness (iFT).

Methods

iFT was measured using the Chevron-Notched Beam (CNB) method with a novel modified split-CNB sandwich specimen design. One hundred human third molars were sectioned into enamel-dentin rods, adhesively conditioned, notched, and cut apart in the dentin area. Specimens were bonded using the universal luting resin in self-adhesive mode or with their corresponding adhesive system/primer (RelyX Universal and Scotchbond Universal Plus, Solventum; GCem One and Adhesive Enhancing Primer, GC Corp.). A gold standard adhesive (OptiBond FL, Kerr) in combination with a flowable resin composite as luting material (x-tra base Universal, VOCO) served as a control. The influence of storage time (24 h vs. 180 days), application mode (adhesive vs. self-adhesive), and the material itself on the iFT measured as fracture toughness in mode I (KIc) according to ASTM C1421–10 was evaluated. Scanning electron microscopy (SEM) was employed to analyze interfacial characteristics and failure modes.

Results

Statistical analysis (Kruskal-Wallis H test with Bonferroni-Holm correction) revealed significant differences in iFT between the groups. Specimens stored for 180 days exhibited lower iFT compared to those stored for 24 h. The adhesive application significantly enhanced iFT relative to the self-adhesive mode. GCem One with Adhesive Enhancing Primer (24 h) exhibited the highest interfacial fracture toughness among all investigated groups. SEM analysis indicated a predominance of adhesive failures at the dentin-resin interface, particularly within the self-adhesive groups.

Conclusions

The application mode and material significantly influence interfacial fracture toughness. The adhesive-assisted application enhances bond stability, while the self-adhesive approach exhibits lower long-term adhesion.

Clinical significance

The use of universal resin cements along with their adhesive system/primer significantly enhances adhesion between the tooth and the restoration, leading to improved long-term clinical success. For restorations without microretention, universal resin cements must be used in combination with their adhesive system/primer.

Keywords

Universal resin cements

Adhesion

Fracture toughness

Dentin

Chevron-notched beam

Self-adhesive

Adhesive

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© 2025 The Authors. Published by Elsevier Inc. on behalf of The Academy of Dental Materials.