Comparing the effectiveness of desensitizing toothpastes on the dentin bond strength of a new self-cured universal adhesive

Purpose This study aims to evaluate the shear bond strength (SBS) of dentin using a new self-cured universal adhesive after the application of various desensitizing toothpastes. Materials and Methods Fifty permanent third molar teeth were prepared by removing roots and enamel surfaces to expose the buccal and lingual dentin surfaces mesiodistally. Specimens were then randomly divided into five groups: Sensodyne Repair & Protect (Group 1), Ipana Pro-Expert (Group 2), Colgate Sensitive Pro-Relief (Group 3), Prevdent (Group 4), and Group 5 served as the control group where no toothpaste was applied. An electric toothbrush was used to brush the teeth twice daily for 14 days, each session lasting 15 seconds. Each group was further divided into two subgroups for bonding procedures using Clearfil SE-Bond (CSB) and Tokuyama Universal Bond (TUB). Composite resin was applied to all sample surfaces following the adhesive procedures. After undergoing 5,000 thermal cycles, the SBS test was conducted. Data were analyzed using two-way ANOVA and post hoc Tukey test (p<0.05). Scanning electron microscopy (SEM) was employed to assess the toothpaste's ability to occlude dentinal tubules, while stereomicroscopy (x40) was used for failure analysis. Results The data indicated that the highest mean SBS value among all groups was observed in CSB/Group-5 (13.83 MPa), while the lowest mean SBS value was recorded in TUB/ Group-4 (5.21 MPa). SEM analysis showed significant tubule occlusion in the group treated with nanohydroxyapatite-containing toothpaste. Conclusion The study found that toothpaste containing nanohydroxyapatite effectively occludes dentin tubules. Therefore, two-step self-etch adhesive systems might be preferred over self-curing universal adhesives.The selection of adhesive procedures should consider the desensitizing toothpaste's composition.