Article

In vitro fracture behavior of maxillary premolars with metal crowns and several post-and-core systems.

Department of Oral Function and Prosthetic Dentistry, College of Dental Science, University Medical Centre Nijmegen, Nijmegen, the Netherlands.
European Journal Of Oral Sciences (Impact Factor: 1.73). 07/2006; 114(3):250-6. DOI: 10.1111/j.1600-0722.2006.00357.x
Source: PubMed

ABSTRACT The in vitro fracture behavior of severely damaged premolars, restored with metal crowns with limited ferrule and several post-and-core systems, was investigated. Crowns of maxillary premolars were removed and canals were prepared with Gates Glidden drills and with Parapost drills. Groups of 11 samples were each treated with cast post-and-cores (Parapost XP, Wironium Plus) (group 1), prefabricated metal posts (Parapost XH) (group 2), prefabricated glass fiber posts (Parapost FiberWhite) (group 3), and custom-made glass fiber posts (EverStick Post) (group 4). Posts and composite cores and metal crowns in groups 2, 3, and 4 were adhesively cemented. Post-and-cores and crowns in group 1 were cemented with phosphate cement. Thermocycling was performed (6,000x, 5-55 degrees C). Two static load tests (30 degrees ) were applied. During the first load test (preloading) no failures occurred. Failure modes from the second load test were categorized into favorable and unfavorable failures. Mean failure loads among the four groups (group 1, 1,845 N; group 2, 1,718 N; group 3, 1,812 N; and group 4, 1,514 N) were not significantly different. Unfavorable failures were root fractures and favorable failures were postcrown displacements. No differences in frequencies of unfavorable/favorable failures were seen among the groups. The results suggest that different post-and-core systems have no influence on the fracture behavior of severely damaged premolars restored with metal crowns with limited ferrule.

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    • "The fracture susceptibility of teeth restored with posts may be related to factors such as the amount of remaining tooth structure, which provides resistance to the fracture of the tooth (Ng et al., 2006), as well as the characteristics of the post, such as the material composition, modulus of elasticity, diameter, and length (Fokkinga et al., 2006). A Root fracture is the most serious type of failure in post-restored teeth (Testori et al., 1993; Wu et al., 2004). "
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    • "resulting in fewer root fractures [2] [3] [4] [5] [6]. Other studies claim that if a severely damaged tooth is restored with a metal crown with a ferrule (collar) around the root, the post material does not play a big role in terms of fracture resistance [7] [8]. On the other hand, there are also studies showing that higher fracture resistance and fewer catastrophic failures are observed in teeth restored without a post [9] [10] [11] [12] [13] [14] [15]. "
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    • "complex resistance (Sorensen & Martinoff 1984, Trope et al. 1985, Assif & Gorfil 1994), providing enough retention and stability only for the prosthesis or coronal restorative material (Christensen 1996). In addition, the geometry, extension and mechanical properties of the post (Caputo & Hokama 1984, Sirimai et al. 1999, Fokkinga et al. 2006) could have an effect on dentine stress distribution, reducing the risk of root fracture. Posts with mechanical properties similar to dentine, which may distribute homogenously the stresses induced by occlusal forces, are favourable in reducing the likelihood of tooth fracture (Caputo & Hokama 1987, Boschian Pest et al. 2002). "
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