Effects of fiber-post placement techniques on tooth fracture resistance

OBJECTIVES: The aim of this in vitro study was to compare two different fiber post placement techniques and two glass fiber post systems on reinforcement of root-filled premolar teeth with mesio-occluso-distal (MOD) cavities. METHODS: Seventy extracted single-rooted human maxillary premolars were randomly assigned to seven groups (n = 10). Group 1 (control) did not receive any preparation. From groups 2 to 7 the teeth were root filled and standard MOD cavities were prepared. Group 2 was kept unrestored. Group 3 was restored with nano-hybrid composite (Synergy/D6, Coltène/Whaledent) using a self etch adhesive (One Coat Bond, Coltène/Whaledent). Group 4-6 were restored with two endodontic glass fiber post systems using self adhesive resin cement (Fiber Post RelyX, 3M-Espe and Dentoclic, Itena). The fiber post was sectioned 2mm under of the occlusal surface and the composite restoration was placed. Group 5-7 were restored with endodontic glass fiber post using self adhesive resin cement. The coronal 2mm of the post remained outside the root canal and a base was prepared (2x2x2mm) around the post with the adhesive cement and cavity was restored with nano-hybrid composite using a self etch adhesive. Compressive loading of the teeth was performed by a universal testing machine at a crosshead speed of 0.1 mm min-1 until fracture. The data were recorded in Newton and submitted to ANOVA and Tukey's Multiple Comparison tests. RESULTS: Groups 5 and 7 had significantly greater (P < 0.05) fracture resistance than groups 4 and 6. No significant differences were found between groups 4 and 6, 5 and 7 (P > 0.05). CONCLUSIONS: Glass fiber-post systems and a base around the post with the adhesive cement increased significantly fracture resistance of premolars with MOD cavities.