Objectives: Evaluation of different post-and-core systems for their fracture behavior at monotonously increasing loads subsequent to cyclic loading. Methods: This in vitro study examined the following post-and-core systems (each n=10): Perma-dor biodent post (palladium alloy) (DeguDent) [A], AF1/palladium-free (DeguDent) [B], ER platinum-iridium post (palladium-free) (Komet) [C], copy-milled ceramic post-and-cores (Celay procedure; Alumina blanks (Al₂O₃) [D] and Zirconia blanks (ZrO₂-reinforced Al₂O₃) (all Vita/Mikrona) [E]), Cerapost (ZrO₂) (Komet) [F], Composipost (carbon-fiber) (RTD) [G]. The control group consisted of root-filled teeth without posts [H]. The test teeth were identically fabricated roots corresponding to an upper central incisor made of a composite with a module of elasticity similar to that of dentine. All post-and-cores were inserted in the roots using Panavia. Subsequently, standardized crowns were cemented onto all roots. The cyclic loading (1.2 × 10⁶ cycles; 1.4 Hz; 30 N) was applied using a Willytec chewing simulator. For alternating and fracturing loading, the desmodont was simulated by an elastomeric material (Permadyne). The teeth were loaded palatally (135°; 0.5 mm/min) on an universal testing machine until fracture. Results: The following fracture load values (medians) were obtained: Metal posts: A: 475.4 N; B: 444.7 N; C: 422.4 N. The Kruskal-Wallis test (P £ 0.05) did not yield any significant differences between these three post-and-core systems. For the ceramic posts, medians of 432.2 N [D], 488.8 N [E], and 416.4 N [F] were found and 515.7 N for the carbon-fiber post [G]. For the control [H], a median of 363.4 N was obtained. The Zirconia post [E] differed significantly from F and H. Significant differences also existed between the carbon-fiber post on one hand and D, F, and H on the other. Conclusion: With regard to fracture behavior under load, carbon-fiber and Celay Zirconia posts are alternatives to the clinically proven Perma-dor post (Ottl and Lauer 1998).

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