Is the application of a silane-based coupling agent necessary to stabilize the fatigue performance of bonded simplified lithium disilicate restorations?

• Published in: Journal of the mechanical behavior of biomedical materials 2022-02, Vol.126, p.104989-104989, Article 104989
• Main Authors: Dapieve, Kiara Serafini, Pilecco, Rafaela Oliveira, Pivetta, Jordana Pavanelo, Machry, Renan Vaz, Werner, Arie, Kleverlaan, Cornelis Johannes, Pereira, Gabriel Kalil Rocha, Valandro, Luiz Felipe
• Format: Article
• Language: English
• Subjects: Acid etching; Cementation; Ceramics; Dental Bonding; Dental Porcelain; Dental Stress Analysis; Hydrofluoric Acid; Materials Testing; Mechanical phenomena; Reproducibility of Results; Resin Cements; Silanes; Surface Properties
• ISSN: 1751-6161; 1878-0180
• DOI: 10.1016/j.jmbbm.2021.104989

This study evaluated the influence of ceramic surface conditioning and storage regimen (baseline vs. aging) on the fatigue performance of simplified lithium disilicate glass-ceramic restorations. A total of 90 ceramic discs (Ø= 10 mm; thickness= 1.0 mm) were allocated into 6 groups (n= 15), considering 2 factors: “ceramic surface treatment” – CA (only silane-based coupling agent, Monobond N), HF (5% hydrofluoric acid etching), or HF+CA (5% HF acid etching plus silane-based coupling agent); and “storage regimen” – baseline (24 hours – 5 days of distilled water at 37 °C), or long-term aging (180 days of distilled water at 37 °C + 25,000 thermal cycles). After intaglio ceramic conditioning, adhesive bonding (Multilink N) was performed onto epoxy resin discs (Ø= 10 mm; thickness= 2.5 mm) and the bonded sets were subjected to step-stress fatigue tests (initial load: 200 N; step-size: 50 N; 10,000 cycles per step; 20 Hz). Fatigue data were analyzed using Kaplan-Meier and Weibull statistical analyses. Fractography and topography analyses were also conducted. The fatigue findings demonstrated that the performance among groups for both baseline and aging conditions maintained a tendency: the CA groups had the worst behavior (baseline: 893 N/143,667 cycles; aging: 639 N/84,179 cycles), while the surface etching with HF (baseline: 1247 N/214,333 cycles; aging: 816.67 N/128,333 cycles) and HF+CA groups (baseline: 1290 N/222,333 cycles; aging: 900 N/145,000 cycles) had no statistically significant difference between them. The aging protocol reduced the performance of all groups. The groups with better fatigue performance (HF and HF+CA) did not have statistical differences regarding structural reliability (Weibull modulus). Most failures were radial cracks from the cementation interface, except for CA aging specimens, with 27% failing from debonding. The HF etching led to noteworthy surface topographical alterations. Micromechanical interlocking resulting from HF acid etching remained prevalent in the fatigue behavior. Thus, the silane-based coupling agent (Monobond N) does not need to be applied after HF etching in terms of fatigue behavior outcomes. •Hydrofluoric acid etching is a must for proper fatigue behavior of lithium disilicate restorations.•The use of silane-based coupling agent alone induces a lower fatigue behavior and high rate of debonding.•Silane-based coupling agent application does not influence the fatigue behavior and can be disconsidered for fatigue