Influence of Surface Conditioning Protocols on Glass-Fiber Post Adhesion Performance After Aging and Flexural Strength

Abstract

The effect of surface-conditioning of fiber-posts on the flexural strength of the post and on the adhesion between the root dentin and cement and between the fiber-post and the composite core were assessed. The fiber-posts were subjected to cleaning with alcohol (AL), treatment with AL + silane (SIL), sandblasting with Al₂O₃ particles + SIL, H₂O₂ etching + SIL, hydrofluoric acid etching + SIL, and H₃PO₄ etching + SIL. For comparison, another group of specimens was left unconditioned (control group). The conditioned fiber-posts were cemented to bovine roots, and standardized cylindrical resin cores were fabricated. The specimens were subjected to 10⁶ mechanical pulses and then sectioned perpendicular to the long axis of the root. Push-out tests were conducted on the sliced root sections, and microtensile testing was applied to the trimmed sliced core sections. The posts were also subjected to three-point bending tests. The surface-conditioning did not have any significant effect on the push-out strength. However, silanization increased the microtensile strength at the resin core. Sandblasting significantly decreased the flexural strength as compared to other surface treatments. Our study indicates that post surface-conditioning did not improve the post retention in the root canal, although silanization enhanced the adhesion to the core resin. Sandblasting with 125-µm alumina particles should be avoided.

KEYWORDS:

• Adhesion promoter
• Aging
• Flexural strength
• Interface

ACKNOWLEDGMENTS

The authors thank the National Council of Technological and Scientific Development for financial support (process numbers 133343/2009-0 and 470365/2009-9), FGM Dental Products for donating materials, and Special Program for International Publications/PRPGP/UFSM for language support.

Notes

a) Cleaning with 96° alcohol.

b) Application of silane coupling agent (Ceramic Primer, 3 M/ESPE) followed by 5 min of rest for drying.

c) Sandblasting with 125-µm Al₂O₃ (distance = 10 mm, perpendicular to surface, for 20 s, pressure of 2.8 bar).

d) Immersion in 10% H₂O₂ for 20 min, rinsing, and drying.

e) Etching with 10% hydrofluoric acid (HF) for 1 min, rinsing, and drying.

f) Etching with 37% phosphoric acid (H₃PO₄) for 1 min, rinsing, and drying.

*Adhes CD: Adhesive failure between cement and dentin.

Adhes PC: Adhesive failure between post and cement.

Cohes P: Cohesive failure of the post.

Cohes PD: Cohesive failure of post and dentin.