Evaluation of different surface treatments on fiber post cemented with a self-adhesive system

Surface treatment of fiber-reinforced posts can increase adhesion, especially on the post/resin cement interface. The purpose of this in vitro study was to evaluate the effect of different surface treatments on fiber post cemented with a self-adhesive system. Sixty fiberglass epoxy resin posts were cleaned, dried and divided into 6 groups (n=10): Control (no surface treatment), silane (silane coupling agent was applied homogeneously on surface), 24% hydrogen peroxide (H₂O₂) (immersion during 1min), blasting (blasting with aluminum oxide for 30s), NH₃ plasma (plasma treatment for 3min) and HMDSO plasma (plasma treatment for 15min). After the treatments, posts were inserted into a silicon matrix that was filled with the resin cement RelyX U200. Afterwards, the post/cement specimens were cut perpendicularly to the long axis of the posts into six 1.0mm thick discs and submitted to a push-out bond strength (POBS) test. Failure pattern was classified in 5 types: type I: cohesive in post; type II: cohesive in cement; type III: cohesive post and cement; type IV: adhesive post/cement; and type V: mixed (association between cohesive and adhesive). Data were analyzed by one-way ANOVA and Tukey HSD post hoc test (α=0.05). Silane (15.94±6.5), blasting (13.13±3.6), NH₃ plasma (14.44±4.0) and HMDSO plasma (13.23±5.3) showed higher POBS when compared to control (p<0.05) and similar among them. H₂O₂ (9.40±4.0) treatment showed POBS values statistically similar to control (9.65±3.6). Failures were predominantly cohesive post and cement, type III, in all groups. In conclusion, surface treatments influenced in the adhesion of fiberglass post with the self-adhesive cement RelyX U200. Silane, blasting with aluminum oxide and plasmas (NH₃ and HMDSO) showed results superior to 24% hydrogen peroxide.