Retention of four endodontic posts cemented with composite resin.

Retention was compared of an active post system (Flexi-Flange), a metal passive prefabicated post system (ParaPost), a passive prefabricated burnout post system (ExactaCast) with and without grooved dentin walls, and a zirconium oxide ceramic post design (Cerapost). The Flexi-Flange with Flexi-Flow Natural cement obtained the highest retentive value of 270.4 lb. The Cerapost cemented with Universal Cement had the lowest retention value of 23.4 lb. The ExactaCast with grooved dentin walls was significantly stronger than the ExactaCast without grooving, the ParaPost, and the Cerapost. The two ExactaCast groups and the ParaPost group had higher retention than the Cerapost group.