OBJECTIVES: Stress transmission to the root through passive fitting dental posts is partly influenced by the thickness of the cement layer between the post and the prepared root canal surface as well as the fit of the post in the root canal. The objective of this study was to compare the cement gap between the post surfaces and the root canals using five prefabricated, tapered, unthreaded titanium posts of different manufacturers, without and with cement. METHODS: Following the endodontic treatment with hand instruments of 100 intact anterior teeth, post spaces were prepared using opening drills of the corresponding size of post. Fifty posts were cemented with zinc phosphate cement into the roots for each system while another 50 posts were inserted into the canal without using the cement. After histological sectioning, the cement gap was measured at six sites for three times at the coronal, middle and apical regions between the root canal wall and the post surface under a light microscope before and after cementation. RESULTS: Before cementation, the highest overall cement gap was observed with the Dr Mooser post system (46 microm) and the lowest with the Velva post system and Cylindro-Conical system (30 microm). Significantly less (P0.001) compared with Velva-Post (38, 20 microm) at the coronal and middle part, respectively (Mann-Whitney U-test, Boneferroni correction). Significant differences (P
