Surface Treatments of Quartz Fiber Post: Influence on Adhesion and Flexural Properties

Howard E. Strassler, DMD

Cheleus N, Sharrock P, Degrange M. Am J Dent. 2007;20: 375-379.

Abstract

PURPOSE: To evaluate (1) the effect of various surface treatments to optimize post adhesion, and (2) if there surface treatments had any adverse effect on the overall mechanical and chemical properties of the posts. METHODS: Six experimental batches were set according to the nature of the surface treatments which were followed or not by post silanization. Post surface treatment were: control, chloroform (CHCl₃), and sandblasting (sand) with Al₂O₃ 50 µm. The silane (sil) used was Silane Coupling Agent Calibra. In all cases, a dual-cure bonding agent was applied: Prime and Bond NT + Self Cure Activator. The groups were 1 (control), 2 (sil), 3 (CHCl₃), 4 (CHCl₃ + sil) 5 (sand), 6 (sand + sil). Following surface treatments the posts were embedded in resin composite and the composite-post interfacial strength was investigated with a push-out test. Flexural and fatigue tests were performed to control the mechanical performances of the treated posts. Push-out data were analyzed using two-way ANOVA and Scheffë’s multiple means comparisons test (á = 0.05). SEM observations revealed the topographical modifications induced by sandblasting and the solvent. RESULTS: Sandblasting or surface treatment with chloroform increased the bond strength (P < .001). The best values were obtained with the combination of sandblasting followed by post silanization. The flexural properties were not modified by the surface treatment (P = .072) and all the posts reached 3,000,000 cycles without breaking.

COMMENTARY

Fiber posts used to restore endodontically treated teeth have become a well-accepted treatment modality. While cementation of metal posts is very straightforward—mix the cement, apply the cement within the root canal, and cement the post—fiber posts have potential benefits beyond adding additional retention to the restorative core being placed. Fiber posts can offer the additional benefits of root reinforcement and sealing of the root canal with a resin adhesive cement. To optimize these effects, a resin-based adhesive is used with a dual-cure or self-cure resin cement, or the post is cemented with a self-adhesive resin cement. In almost all of the manufacturer’s instructions with fiber posts, little guidance is given to the clinician how best to optimize the resin-fiber post surface for adhesion with the resin cement.

This research paper investigated a variety of surface treatments to include no treatment, treatment with chloroform, sandblasting, and silane (ceramic primer) of a fiber post and their effect on adhesion and the flexural properties of the post. Based on this study, a combination of sandblasting followed by silane and bonding agent application provided for the best results for increasing fiber post retention to the composite core without modifying the mechanical properties of the quartz fiber post.

About the Author

Howard E. Strassler, DMD Professor and Director of Operative Dentistry Department of Endodontics, Prosthodontics, and Operative Dentistry University of Maryland Dental School, Baltimore, Maryland