Objectives

In recent years, notable advancements have been made in dental adhesive systems. However, the adhesive interface remains the most vulnerable aspect of tooth-composite restorations. This has created a growing demand for simplified adhesives with enhanced performance, prompting the emergence of universal adhesives.

Material and methods

To evaluate the influence of dentin moisture condition and thermocycling on shear bond strength (SBS), failure modes, and adhesive remnant index (ARI) of two universal adhesives, such as M-TEG-P Yamakin Aquabond (methacryloyloxydecyl tetraethylene glycol phosphate) and MDP One Coat Bond (10-methacryloylo­xydecyl dihydrogen phosphate).

Results

Sixty-four extracted maxillary premolars were divided into two main adhesive groups (n = 32 each): Groups 1-4: Yamakin, and groups 5-8: One Coat Bond. Each group was subdivided by moisture condition: dry vs. moist (n = 16 each), and aging condition: immediate vs. thermocycled (n = 8 each). Bonding was performed according to manufacturer instructions, followed by composite build-up. SBS was measured using a universal testing machine, and failure mode was evaluated by XCAM stereomicroscope with ARI. Data were analyzed using ANOVA and Mann-Whitney U tests (a = 0.05).

Conclusions

Statistically significant differences in SBS were observed among the eight subgroups (p < 0.005). The highest SBS was recorded in the One Coat/wet/immediate group (17.2 ± 1.0 MPa), significantly outperforming all other conditions. Thermocycling reduced SBS in both adhesives, with Yamakin groups exhibiting more pronounced degradations. Failure mode analysis revealed a predominance of adhesive failures in Yamakin groups and mixed failures in One Coat groups, aligning with SBS outcomes.