Retention of three post and core systems with and without etching

The retentive strength of post and cores fabricated entirely of composite material was compared to the retentive strength of Para Posts with composite cores in etched and unetched post preparations. Under tensile forces exerted upon the cores, only one post was removed. In all other samples the posts remained firmly embedded within the roots. The core material fractured at the occlusal surface of the roots. The Para Post with Composite core cemented into etched preparations was significantly more resistant to fracture than all other samples.