Evaluation of microtensile bond strength to dentin and adhesive layer thickness of a new generation two-bottle universal adhesive

Purpose: This study aimed to evaluate and compare the immediate and aged microtensile bond strengths (μTBS) and pre-aging adhesive layer thicknesses of G2-Bond Universal, a novel two-bottle universal adhesive, with those of the gold-standard two-step self-etch adhesive (Clearfil SE Bond) and one-step universal adhesive (G-Premio Bond). Materials and Methods: Thirty extracted human molars were randomly assigned to three adhesive systems (n=10 teeth per group). After standardized dentin surface preparation, adhesives were applied according to manufacturers' protocols, followed by incremental composite build-up. Specimens were sectioned to obtain rectangular prism-shaped sticks (1 mm² cross-sectional area), which were allocated to immediate and 6-month water aging subgroups (n=90each). μTBS was measured using a universal testing machine. Adhesive layer thickness was assessed on 90 pre-aging sticks via scanning electron microscopy, with measurements performed using ImageJ software. Data were analyzed using two-way ANOVA for μTBS and one-way ANOVA for adhesive thickness, followed by Tukey's HSD. Results: Aging showed no statistically significant effect on μTBS (p>0.05). Clearfil SE Bond exhibited the highest µTBS values, significantly outperforming G-Premio Bond (p0.05). G2-Bond demonstrated the thickest adhesive layer. Conclusion: The thicker adhesive layer of G2-Bond may enhance its mechanical resilience and clinical durability under functional stresses.