الفهرس 
An immunohistochemical study on expression of MDM2 in mucoepidermoid carcinoma and adenoid cystic carcinoma
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Abstract
The purpose of this study was to investigate the effect of load directions on fracture resistance of endodontically treated teeth restored with novel post system(positive locking post 2Wurzburg post system3 in comparison to the standard custom made post and core. Twenty mandibular second premolars with similar dimensions were collected. All teeth received endodontic treatment and were prepared to receive the different post systems. teeth were divided into two groups (n = 10) according to the post type. group I (receiving wurzburg post hager and meisinger, gmbH, germany) and group II ( receiving custom made post and core Ni - Cr, Wiron 99: BEGO, bremer, germany). Different posts were cemented using dual - cured resin cement (Rely X unicem, 3M ESPE). All samples received metal ceramic crowns. Each group was further subdivided into two subgroups (n = 5) according to the angle of load application; subgroup A: Load was applied at 90 degrees (vertical load along the long axis of the tooth ) and subgroup B: Load was applied at 45 degrees. To investigate the effect of different post systems on the fracture resistance, compressive load of 5 KN was applied vertically parallel to the long axis of the teeth in subgroup A and at a 45{u00B0} angle to the long axis of the teeth in subgroup B until fracture occurred