Microtensile bond strength between a quartz fiber post and a resin cement: effect of post surface conditioning

To test the bond strength between a quartz-fiber-reinforced composite post (FRC) and a resin cement. The null hypothesis was that the bond strength can be increased by using a chairside tribochemical silica-coating system.

Thirty quartz-FRCs (Light-Post) were divided into 3 groups according to the post surface treatment: G1) Conditioning with 32% phosphoric acid (1 min), applying a silane coupling agent; G2) etching with 10% hydrofluoric acid (1 min), silane application; G3) chairside tribochemical silica coating method (CoJet System): air abrasion with 30-microm SiOx-modified Al2O3 particles, silane application. Thereafter, the posts were cemented into a cylinder (5 mm diameter, 15 mm height) with a resin cement (Duo-Link). After cementation, the specimens were stored in distilled water (37 degrees C/24 h) and sectioned along the x and y axes with a diamond wheel under cooling (Lab-cut 1010) to create nontrimmed bar specimens. Each specimen was attached with cyanoacrylate to an apparatus adapted for the microtensile test. Microtensile testing was conducted on a universal testing machine (1 mm/min). The data obtained were submitted to the one-way ANOVA and Tukey test (alpha = 0.05).

A significant influence of the conditioning methods was observed (p < 0.0001). The bond strength of G3 (15.14 +/- 3.3) was significantly higher than the bond strengths of G1 (6.9 +/- 2.3) and G2 (12.60 +/- 2.8) (p = 0.000106 and p = 0.002631, respectively). Notwithstanding the groups, all the tested specimens showed adhesive failure between the resin cement and FRC.

The chairside tribochemical system yielded the highest bond strength between resin cement and quartz-fiber post. The null hypothesis was accepted (p < 0.0001).