Influence of surface treatment on bonding effectiveness of different fiber-posts

Objectives: To evaluate the effect of post pre-treatment on the bond strength of three adhesive cements to three post systems.

Methods: Three kinds of glass-fiber reinforced posts with a different matrix, namely epoxy resin (RelyX-Posts, 3M ESPE), methacrylate resin, (GC-posts, GC) and composite resin (FRC Plus, Ivoclar-Vivadent), and three types of resin cements, namely Bis-GMA-based (Variolink II, Ivoclar-Vivadent), 10-MDP-based (Clearfil Esthetic Cement, Kuraray) and self-adhesive (RelyX-Unicem, 3M ESPE), were used. Posts were not treated (control), treated with silane, or treated with Cojet/silane. Overall, 27 groups of 8 specimens each were tested. Posts were inserted up to 9 mm depth into composite blocks (Paradigm, 3M ESPE). After one week storage at 37°C, three sections (coronal, middle, apical) of 2 mm thickness were subjected to a push-out test using a universal loading device (5848-MicroTester, Instron, USA).

Results: Regarding the kind of post, the significantly highest push-out bond strength was observed for RelyX-Posts and GC-Posts (p<0.01). Regarding the post pre-treatment, the Cojet/silane treatment significantly improved the bond strength (p<0.01) for FRC Plus and GC-Posts. Regarding the cement, RelyX-Unicem scored higher (p<0.01).

Mean push-out bond strength (SD)
Post		Cement
	RelyX-Unicem	Clearfil Esthetic Cement	Variolink II
RelyX-Post
Untreated	12.40(2.67)abcd	8.42(2.02)ghilm	9.87(2.59)defgh
Silane	10.36(3.53)cdefg	8.41(2.53)ghilm	9.16(3.52)fghil
Cojet/Silane	14.49(3.39)a	9.30(3.86)fghil	8.80(2.50)fghilm
FRC Plus
Untreated	11.11(1.99)bcdef	7.30(2.89)hilmn	5.39(1.64)n
Silane	10.93(3.44)bcdefg	7.46(2.79)hilmn	5.39(2.20)n
Cojet/Silane	12.05(2.54)abcde	9.72(3.52)efghi	7.21(3.44)ilmn
GC-Post
Untreated	8.93(1.77)fghilm	6.4(1.97)lmn	6.34(1.73)mn
Silane	11.15(2.23)bcdef	6.97(3.04)lmn	9.20(3.20)fghil
Cojet/Silane	14.42(2.59)a	13.23(2.30)ab	12.86(3.25)abc
ANOVA: different superscript letters indicate significant difference (p<0.05)

The push-out bond strength was also found to be significantly different for the coronal, middle and apical sections (p>0.01).

Conclusion: Overall, the epoxy resin posts presented the best results. Silanization was not effective in enhancing the bond strength of any post system. Coating with silicated-alumina particles appeared to improve the bond strength to composite and methacrylate posts.