Purpose to compare fracture resistance of endodontically treated teeth restored with different lengths of fiber posts.
Materials and methods: Thirty- two freshly extracted sound mandibular premolars of approximate sizes, were mounted centrally and vertically in 12 x 12 x 20 mm acrylic block. Then, decoronated 2 mm above the cemento-enamel junction and were endodontically treated.
Teeth were randomly divided between 4 main groups (n= 8). For all groups, post holes were prepared (group A; post hole less than the crown length (3 mm), group B; post hole equal to the crown length (5 mm), group C; post hole half of the root length (7 mm), group D; post hole 2/3 of the root length (9 mm). Posts were cemented using self-adhesive resin cement. Using core former and light-cured core composite, cores for all specimens were built. A 0.5 mm finish line was prepared with 2 mm ferrule, to receive metal coping. Using universal testing machine, axial loadwas applied at crosshead speed of 0.5 mm/min, parallel to long axis of the tooth until failure.
Results: Group D scored the highest mean fracture resistance values (2670 ± 597.37 N) followed by Group A (2668 ±316.67 N) and Group B (2609 ±523.15 N). Group C scored the lowest fracture resistance values (2517 ±464.35 N). One-way ANOVA revealed no significant difference between groups (P=0.9). Chi-squre test also revealed no significant difference in restorability between the studied groups. (P=0.2).
Conclusions: The tested post lengths had no significant effect on fracture resistance of endodontically treated teeth. Posts having radicular lengths equal to half of the root, showed the most non-restorable fracture pattern among all tested groups.