Effect of ferrule and post placement on fracture resistance of endodontically treated teeth after fatigue loading

Objectives luate the influence of the ferrule effect (1) and the fibre-post placement (2) on the fracture resistance of endodontically treated teeth subjected to cyclic fatigue loading. s racted single-rooted upper pre-molars were sectioned at the CEJ (groups a and b) or 2 mm above the CEJ (groups c and d), and subsequently endodontically treated. After 24-h water storage at 37 °C, specimens were restored according to four build-up approaches (n = 10 per group): (a) NF–NP (no ferrule, no post), (b) NF–P (no ferrule, fibre-post), (c) F–NP (ferrule, no post) and (d) F–P (ferrule, fibre post). RelyX Posts (3M-ESPE) were used in groups NF–P and F–P, and were cemented with Panavia F 2.0 (Kuraray). A standardized composite core was built, after which specimens were restored with an all-ceramic crown (IPS Empress CAD, Ivoclar-Vivadent) Specimens were fatigued by exposure to 1,200,000 cycles using a chewing simulator (Willytech). All specimens that survived fatigue loading were fractured using a universal loading device (Micro-Tester, Instron). A two-way analysis of variance was used to determine the statistical significance of the factors ferrule and post on fracture resistance. s ne NF–NP specimen failed under fatigue. The ferrule effect significantly enhanced the fracture resistance of the restored teeth, regardless the use of a post (p = 0.003). F–NP obtained the highest fracture resistance (758.52 ± 121.89 N), which was not significantly different from F–P (647.58 ± 132.95 N); NF–NP presented the lowest fracture resistance (361.52 ± 151.69 N). For all groups, only ‘repairable’ failures were recorded. sions ng extra-removal of sound tooth structure, rather than placing a fibre post, can protect endodontically treated teeth against catastrophic failure. However, when any ferrule can be preserved, a fibre-post may improve the retention and fatigue resistance of the restoration.