# Influence of Dimethyl Sulfoxide Pretreatment on the Push-Out Bond Strength of Fiber Posts Using Total-Etch and Self-Etch Adhesives: An In Vitro Study

## TL;DR

This study found that using dimethyl sulfoxide (DMSO) with certain dental adhesives significantly improves the bond strength of fiber posts in treated teeth.

## Contribution

The study demonstrates that DMSO pretreatment enhances fiber post bond strength when used with multistep adhesives, but not with universal adhesives.

## Key findings

- Group II using FL Bond II System with DMSO showed the highest bond strength (2.34 MPa).
- DMSO pretreatment with multistep adhesives significantly improved bond strength compared to universal adhesives.
- No significant bond strength improvement was observed with universal adhesives regardless of DMSO use.

## Abstract

Background and aim

Endodontically treated teeth often require post placement to reinforce structural integrity. Fiber posts are preferred over metallic ones due to their elastic modulus, which is closer to that of dentin. Dimethyl sulfoxide (DMSO), known for its tissue penetration and solvent properties, has recently been explored as a dentin pretreatment to enhance adhesive performance. This study aimed to evaluate the effect of DMSO pretreatment on the push-out bond strength of fiber posts luted with different adhesive protocols, including self-etch and total-etch systems.

Materials and methods

Forty extracted human teeth were standardized and subjected to root canal treatment. Following post space preparation, the teeth were randomly divided into four groups (n = 10) based on adhesive protocols: Group I, total-etch + DMSO + single-step, seventh-generation universal adhesive (Palfique, Tokuyama Dental Corp., Tokyo, Japan); Group II, total-etch + primer + DMSO + three-step, fourth-generation adhesive (FL Bond II System, Shofu Inc., Kyoto, Japan); Group III, total-etch + DMSO + primer + three-step, fourth-generation adhesive (FL Bond II System, Shofu Inc.); and Group IV, self-etch + DMSO + single-step, seventh-generation universal adhesive (Palfique, Tokuyama Dental Corp.). Fiber posts were cemented using Estecem Plus resin cement and light-cured. All specimens were sectioned and subjected to push-out bond strength testing using a universal testing machine. Data were analyzed using IBM SPSS Statistics for Windows, Version 25.0 (Released 2017; IBM Corp., Armonk, NY, USA). One-way ANOVA was used for intergroup comparisons, Tukey’s post hoc test for multiple pairwise comparisons, and repeated-measures ANOVA for intragroup comparisons. Statistical significance was set at p < 0.05.

Results

Group II (2.34 MPa) showed the highest mean push-out bond strength. Statistically significant differences were observed between Groups II (2.34 MPa) and IV (1.39 MPa), III (2.24 MPa) and IV (1.39 MPa), I (0.68 MPa) and II (2.34 MPa), and I (0.68 MPa) and III (2.24 MPa). No significant differences were found between Groups II (2.34 MPa) and III (2.24 MPa) or between Groups I (0.68 MPa) and IV (1.39 MPa).

Conclusions

The application of DMSO in combination with the FL Bond II System, either before or after primer application, significantly enhanced the bond strength of fiber posts. Universal adhesives showed lower bond strength regardless of the etching protocol, suggesting that DMSO pretreatment is more effective when used with multistep adhesive systems.