Tensile Bond of Cemented Fiber Posts

As fiber posts become more frequently used in esthetic dentistry, it is necessary to investigate the cements and adhesive systems used to retain these posts.  Self adhesive cements eliminate etching and priming steps involved with adhesive post cementation. Objective: To measure and compare the tensile bond strength of 4 cements when used to cement 8 mm composite fiber posts in single rooted extracted teeth. Methods:  40 lower first premolars were sectioned with separating disks at the CEJ. The canals were accessed with rotary files to clean and shape the root canal. The largest apical file size of 45 was taken to a working length 1mm short of the apex. The canals were obturated with gutta percha. The roots were notched, embedded into acrylic and post spaces prepared with a post space bur. The teeth were divided into 4 groups with 10 teeth per group, and the 8mm fiber posts (GC Corporation) were cemented following the manufacturers' directions. The specimens were stored in water at 37⁰C for 24 hours. 3mm apical part was removed and remaining 5mm coronal section was tested. An acrylic fixture was placed over the end of the post extending from the tooth which was used to grasp the post during testing.  A tensile load was applied to the fiber posts until failure using an Instron (model 5565) with crosshead speed of 1mm/min. ANOVA and Tukey/Kramer post hoc test was used to compare intergroup differences (p=.05). Results: The peak failure loads were (N) 68±20 PanaviaF 2, 147±33Rely X UniCem Aplicap,/3MESPE; 129±27 - GCem,/GC; 68±20 – BisCem/BISCO, 109±27 – PanaviaF/Kuraray. BisCem produced tensile loads significantly lower than GCem, PanaviaF, or Unicem (p<0.05). All other comparisons were not significant. Conclusions: Self adhesive cements Unicem and GCem are possible alternatives for post cementation. Supported in part by GC America.