Bond Strength of Fiber Posts to the Root Canal: Effects of Anatomic Root Levels and Resin Cements

Statement Of Problem: Decementation is one of the most frequent causes of failure in the post-cement system. The bond strength in different parts of the canal may be influenced by technical and anatomic factors.

Purpose: The purpose of this in vitro study was to assess the effects of anatomic root levels to reach the canal and different resin cements on the bond strength of fiberglass posts along the canal.

Material And Methods: One hundred thirty-five roots of bovine teeth were endodontically treated, prepared with 15-mm-long post spaces and divided according to the anatomic root level: coronal (with 15-mm post space), middle (with 10-mm post space), and apical (with 5-mm post space). Fiberglass posts were luted with the cements (n=15): conventional resin cement with 3-step etch-and-rinse adhesive system (RelyX ARC/SBMP); self-adhesive resin cement (RelyX U200) and autopolymerizing resin cement with etch-and-rinse adhesive system (C&B/All-Bond 2). After 24 hours, specimens were sectioned and subjected to the push-out test. The maximum extrusion load was recorded (0.5 mm/minute, 200 N). Data were analyzed with analysis of variance (ANOVA) and the Tukey test (α=.05). Failure mode was analyzed by using multinomial logistic regression.

Results: There were no significant effects of resin cements (P>.05). The bond strength at apical third was higher when the canal was reached at the apical level than at the coronal level (P=.022). When each root level was directly reached, the coronal bond strength was lower than apical (P=.001) and middle (P=.021) for all cements.

Conclusions: When the canal was reached at the coronal, medium, and apical levels, the bond strength of conventional, self-adhesive and autopolymerizing resin cements was lower in the coronal root third.