In vitro evaluation of push-out bond strengths of various luting agents to tooth-colored posts

Statement of problem. Different compositions of tooth-colored posts may influence the bonding capacity of various luting agents to these posts. An appropriate understanding of these interactions is presently unavailable. Purpose. This study initially evaluated the effects of various pretreatment procedures on bond strengths to zirconium-oxide Posts using a phosphate-methacrylate resin luting agent. Following that investigation, the bond strengths of various luting agents to tribochemically coated glass-fiber-reinforced composite (FRC) resin and zirconium-oxide posts were investigated. Material and methods. Two hundred zirconium-oxide posts (CosmoPost) divided into 10 groups (n=20) were luted into artificial post spaces prepared with drills provided by the manufacturer. In 4 groups the posts were luted with phosphate-methacrylate resin agent (Panavia F) after receiving one of the following pretreatment procedures: no treatment (control); airborne-particle abrasion; silica coating and silanization with an intraoral airborne-particle-abrasion device (CoJet); or silica coating and silanization with a laboratory airborne-particle-abrasion device in combination with airborne-particle abrasion (Rocatec). The other zirconium-oxide posts in the 6 remaining groups were silica coated (CoJet), silanated, and luted with 1 of 6 different luting agents (Multilink, Variolink, PermaFlo DC, RelyX Unicem, Clearfil Core, and Ketac Cem). Additionally, 60 FRC posts (FRC Postec) were silica coated (CoJet), silanated, and luted with 1 of the 6 resin luting agents (Panavia F, Multilink, Variolink, PermaFlo DC, RelyX, and Clearfil Core). Push-out tests were performed to evaluate the bond strengths between luting agents and posts. Qualitative scanning electron microscopy (SEM) analyses were performed to evaluate the effects of the pretreatment procedures on the surface of the zirconium-oxide posts. Data were analyzed using analysis of variance (ANOVA) followed by the post hoc Tukey B test (alpha=.05). Results. Bond strengths to the posts were significantly affected by the type Of luting agent and the type of post (P<.001; 2-way ANOVA). Bond strengths of all luting agents to the FRC posts were significantly higher than to the zirconium-oxide posts (P<.01), except for Multilink and PermaFlo DC, which demonstrated higher bond strength values to the zirconium-oxide posts (P<.001). Pretreatment procedures significantly increased the bond strength of Panavia F to the zirconium-oxide posts (P<.05). SEM analyses revealed distinctive irregularities on the surface of the pretreated zirconium-oxide posts compared to the untreated posts. Conclusion. Bond strengths of luting agents to tooth-colored posts arc significantly affected by the type of luting agent and the type of post. All investigated pretreatment procedures of zirconium-oxide posts significantly increased the bond strength of Panavia F.