Optimization of chitosan nanoparticle dentin pretreatment with different concentrations and application times to improve bonding at resin-dentin interface.

Abstract

Aim: The aim was to study the effect of various chitosan nanoparticles (CNPs) solution concentrations with different application times on the microtensile bond strength (µTBS) of resin composite to human demineralized dentin.

Materials and methods: Flat dentin occlusal surfaces from 90 extracted premolar teeth were randomly divided into three pretreatment groups (n = 30) before adhesive application: Group I: 0.2% CNPs, Group II: 0.5% CNPs, and Group III: 1% CNPs. Further, samples were divided into three subgroups (n = 10) based on the different durations of application of CNPs (A: 30 s, B: 60 s, and C: 90 s) and prepared accordingly. Subsequently, after self-etch adhesive application, nanohybrid composite buildup was done. Bonded teeth were sectioned into resin-dentin sticks (0.9 mm²) for µTBS analysis. In addition, stereomicroscopic analysis (×25) was performed to evaluate the failure modes as cohesive, adhesive, or mixed. Data were analyzed using repeated measures of ANOVA along with Wilks' lambda test and Dunn-Bonferroni multiple comparison test (P < 0.05).

Results: The highest and lowest values of µTBS were observed with 0.2% CNPs at 60 s and 1% CNPs at 90 s, respectively (P < 0.05). Stereomicroscopic fracture pattern analysis revealed 50-cohesive, 34-mixed, and only 6-adhesive failures.

Conclusion: The 60 s application of 0.2% CNPs to demineralized dentin before dentin adhesive application enhanced the bond strength at the resin-dentin interface. Overall efficiency varied according to CNPs concentration and application time. Clinical significance: CNPs pretreatment improves bonding effectiveness. This approach creates new possibilities to form a functional bonding interface, thereby prolonging the longevity of restorations.