Fracture Rsistance of Bovine Teeth Restored with Glass Fiber Posts

Objectives: This in vitro study compared the effect of 3 post designs on the fracture resistance and failure modes of endodontically treated teeth .

Methods: Ninety bovine incisors were selected and divided into 9 groups of 10 specimens. The teeth were assigned to 3 groups based on the post design: cylindrical(REFORPOST| FIBER GLASS) , tapered (EXACTO|FIBER GLASS)and double-tapered (WHITE POST DC). Each group was subdivided into 3 sub-groups in accordance with the diameter of the post: small (No.1), medium (No.2), and large (No.3). All posts were cemented with ED Primer dentine adhesive and Panavia F resin cement. Specimens were mounted in acrylic resin blocks with a layer of silicone rubber covering the roots. A universal testing machine compressively loaded the tooth specimens from the palatal side at a crosshead speed of 1mm/min at an angle of 135º to the long axis of the teeth until failure occurred. The failure mode was determined by visual inspection of all specimens. Data were analyzed by one-way analysis of variance - ANOVA and the Tukey test (p<0.05).

Results: The facture resistance was affected by the type of post (P<.0001). The narrower diameter for all of them allowed higher resistance. The main failure mode in the large cylindrical group was catastrophic fractures, while the main failure in the other eight groups were favorable.

Conclusions: It was concluded that the narrower diameters showed higher fracture resistance. The dominant failure pattern was repairable fracture, except for the large cylindrical group.