Clinical studies have shown that
endodontically treated teeth restored with short posts or deficient ferrules show a high failure risk. This study. evaluated the influence of
fatigue loading on the quality of the cement layer between prefabricated
quartz coated
carbon fiber posts with restricted length and the root canal wall in maxillary pre-molars. Two adhesive
resin composite cements, chemical-cured
Panavia 21 (Group 1) and dual-cured
RelyX-ARC (Group 2), and one resin-modified
glass-ionomer cement, chemical-cured RelyX (Group 3), delta were selected for this study. Post- and-core restorations were made on single-rooted human maxillary premolars from which the coronal sections were removed at the level of the proximal cemento-enamel junction (CEJ). Following endodontic treatment, a post-and-core restoration with 6-mm post length was prepared for each tooth. The posts were directly cemented into the root canal and, after applying an adhesive (
Clearfil Photo Bond), they were built up with a core build-up composite (Clearfil Photo Core). For each group (n=8), half of the specimens were exposed to
fatigue loading (10(6) load cycles) almost perpendicular to the axial axis (85 degrees), while the other half were used as the control. Three parallel, transverse root sections, 1.5-mm thick, were cut from each specimen at the apical, medial and coronal location. These sections were examined by Scanning Electron Microscopy (SEM) to evaluate the integrity of the cement layer, while the retention strength of the cemented post sections was determined with the push-out test. The multivariate results of MANOVA showed that the condition main effect (
fatigue or control) was not significant (p=0.059); the two other main effects, type of cement and section location, were significant (p=0.001 and p=0.008). For both the push-out strength and SEM evaluation of the cement layer integrity, the results significantly improved from RelyX to
RelyX-ARC to
Panavia 21 and also from apical to coronal.