Shear Bond Strength of Different Fifth-Generation Dentin Bonding Agents: An In Vitro Comparative Analysis

Fifth-generation dentin bonding agents (DBAs) are widely used in restorative dentistry to achieve reliable adhesion to dentin for composite restorations. This study aimed to compare the shear bond strength (SBS) of four commercially available fifth-generation DBAs to human dentin in an in vitro setting.

This in vitro study was conducted in the Department of Conservative Dentistry and Endodontics on 120 extracted human premolars. The teeth were collected, cleaned, and prepared by sectioning the enamel to create 5 × 5 mm dentin blocks and polished with 600-grit silicon carbide paper. The dentin surfaces were etched with 37% phosphoric acid for 15 s, rinsed, and blot-dried. Samples were randomly divided into four groups (n = 30, 25% each) for the application of different bonding agents: in Group 1, Prime Restorite Bond 5G (Prime Dental Products Private Ltd, Maharashtra, India) was used; it was applied in two coats for 15 s, air-dried for 5 s, and light-cured for 10 s; in Group 2, Prevest DenPro Fusion Bond 5 (Prevest DenPro Ltd, Jammu & Kashmir, India) was used; it was applied similarly but light-cured for 20 s. In Group 3, DentGist Nano-Bond (Rident Denpro Pvt. Ltd., New Delhi, India) was used; it was applied as Group 2 but light-cured for 30 s. In Group 4, Coltene One Coat Bond SL (Coltene, Altstätten, Switzerland) was used; it was applied in one coat for 20 s, air-dried for 5 s, and light-cured for 30 s. Filtek Z250 XT composite resin (3M ESPE, St. Paul, USA) was placed incrementally (2 mm layers, each cured for 20 s) in a 6 × 7 mm polyethylene tube matrix. The samples were mounted in self-curing acrylic resin and tested for SBS using a universal testing machine (Instron, PSI, India) at a crosshead speed of 1 mm/min. Data were analyzed using one-way analysis of variance (ANOVA) and post-hoc tests.

Group 4 (19.92 ± 2.80 MPa) and Group 3 (19.81 ± 2.36 MPa) had the highest SBS, followed by Group 1 (18.63 ± 1.25 MPa), while Group 2 (16.05 ± 0.73 MPa) had significantly lower SBS (p = 0.001). Group 1 showed significantly higher SBS compared to Group 2 (mean difference = 2.58 MPa, p = 0.001), but no significant difference was observed between Groups 3 and 4. Group 2 demonstrated significantly lower values when compared to both Group 3 (mean difference = 3.76 MPa, p = 0.001) and Group 4 (mean difference = 3.87 MPa, p = 0.001).

In conclusion, adhesive composition, particularly solvent type and monomer content, significantly influenced SBS, with DentGist Nano-Bond and Coltene One Coat Bond SL, demonstrating superior performance, guiding clinical adhesive selection for durable restorations.