The present study was carried out to compare between Ti post and Glass fiber reinforced composite post on stress distribution, failure load and mode of in-vitro endodontically treated maxillary central incisors with variable bone support. Both mechanical and computational methods were used. Computational 3-D FEA was used to determine the stresses created in specimens. Mechanical loading of specimens to failure was carried out to determine both failure loads and modes. These experiments aided in correlating stress distribution with both failure load and mode under different testing conditions. It was found that the failure loads and modes of the tested teeth is influenced by both post type and assumed alveolar bone level; Titanium posts provide higher fracture resistance but unfavorable mode of failure to endodontically treated teeth in contrast to fiber reinforced posts which provided lower fracture resistance but more favorable mode of failure. Failure load of endodontically treated teeth restored with tested post systems decrease with decreased simulated alveolar bone level. For both tested posts with decrease simulated bone support concentration of tension stresses increased in root , post and bone but decreased in core and crown. For both post types stresses are more concentrated apically but with less stress values created in case of the tested fiber post thus decreasing the risk for root fracture.