nowadays, by complication of production mechanisms from reservoirs and depletion of most of the reservoirs in iran, secondary production has become more important. regarding the nature of iranian reservoirs and carbonate inherencies and diagenetic and tectonic effects on these reservoirs, we see heterogeneities in them which cause uncertainty in predictions and performance of these reservoirs. ...

STATEMENT OF PROBLEM It is unclear which post and core system performs best when bonded to severely compromised endodontically treated teeth. PURPOSE The purpose of this study was to investigate the fracture resistance and mode of failure of severely compromised teeth restored with 3 different adhesively bonded post and core systems. MATERIAL AND METHODS Thirty extracted endodontically trea...

The purpose of this study was to determine the fracture resistance of 4 post and core systems. 40 extracted maxillary canines (for orthodontic reason) were used for this study. The samples were divided into 4 groups, which were: Group (1) Cast post luted with Rely X ARC; Group (2) Cast post cemented with zinc phosphate; Group (3) Fibre post luted with Rely X + Filtek Z-250 as core material; Gro...

STATEMENT OF PROBLEM Dentin and core materials that substitute for missing dentin are dissimilar materials. A core material with a lower elastic modulus may deform more under applied stress and therefore result in reduced stress concentration at the core/dentin junction. PURPOSE This in vitro study examined the effect of core stiffness on the fracture resistance and failure characteristics of...

Statement of problem: A dowel is essential to retain the core in case of severe tooth destruction. However, the placement of a dowel and core may actually weaken teeth and affect their failure pattern depending on their material properties and stress transfer. Purpose: The present study compared the fracture resistance and failure pattern of endodontically treated premolars with different amoun...

This case report describes the management of an oblique crown-root fracture of maxillary left lateral incisor. After removal of the fractured fragment, endodontic treatment, the remaining tooth was provisionally restored. The tooth was then orthodontically extruded by 3 mm to raise the defect supraginigivally. Periondonal fibres were cut with a surgical blade. A metallic screw type post was ins...

Recent three-point bend tests of size effect on the strength of geometrically scaled sandwich beams of three types – with no notches, and with notches at the upper or lower skin–foam interface, which were previously evaluated using simplified sandwich beam theory and equivalent linear elastic fracture mechanics, are now reanalyzed more accurately by finite elements. Zero-thickness interface ele...

The purpose of this study was to determine the effect of post types and sizes on fracture resistance in immature tooth model with various restorative techniques. Bovine incisors were sectioned 8 mm above and 12 mm below the cementoenamel junction to simulate immature tooth model. To compare various postand-core restorations, canals were restored with gutta-percha and resin core, or reinforced d...

PURPOSE This in-vitro study aimed to evaluate the fracture resistances and failure modes of endodontically treated mandibular premolars restored with endocrowns and conventional post-core retained crowns. MATERIALS AND METHODS Thirty mandibular premolars were assigned into three groups (n=10): GI, intact teeth; GE, teeth with endocrowns; GC, teeth with conventional post-core supported crowns....