In vitro evaluation of the fracture resistance of anterior endodontically treated teeth restored with glass fiber and zircon posts

Abstract

The published information is equivocal regarding the fracture resistance of endodontically treated teeth restored with fiber posts. Additionally, little is known about the biomechanical performance of glass fiber and zircon posts. This in vitro study investigated the fracture resistance of anterior endodontically treated teeth prepared with a 2-mm ferrule, restored with glass fiber and zircon posts and composite resin cores or cast posts and cores. Twelve matched pairs of teeth were obtained from 4 cadavers, and all were endodontically treated and prepared with a standardized 2-mm ferrule. According to a random number table, the 2 teeth from each matched pair were randomly divided into 2 groups. The test group consisted of 12 specimens restored with a glass fiber and zircon post (Fibio) and composite resin (Durafil) core. Twelve matching specimens restored with a nickel-chromium (NiCr) cast post and core served as the control. Specimens in both groups were cemented with resin cement (Panavia F). After cementation of cast NiCr complete crowns with zinc polycarboxylate cement (ShangChi), the specimens were loaded with an incremental static force at an angle of 135 degrees to the long axis of the root until failure occurred. A paired sample t test was used to compare the fracture resistance (N) of teeth restored with the 2 post-and-core systems (alpha=.05). The mean failure load of paired differences between the 2 groups was -261.3+/-237.3 N. The test group exhibited significantly lower failure loads than the control group (P=.004). All specimens displayed root fractures, most of which were oblique, with cracks initiating from the palatal cervical margin and propagating in a labial-apical direction. Within the limitations of this study, the teeth restored with glass fiber and zircon posts demonstrated significantly lower failure loads than those with cast NiCr post and cores. All specimens failed via root fractures.