In vitro fracture behavior of maxillary premolars with metal crowns and several post-and-core systems.
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.
- SourceAvailable from: Mohamed Ibrahim Abu-Hassan08/2011; , ISBN: 978-953-307-504-4
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ABSTRACT: This study evaluated the load bearing capacity of anatomically designed canines restored with FRC posts and experimental short fiber composite resin (FC). The effect of using three different types of tooth preparation and woven net on the fracture load was also investigated. Further aim was to evaluate the failure mode of each restoration. 80 maxillary frasaco-canines were divided into 10 groups (n=8). The anatomic crowns were cut perpendicular at CEJ of the tooth. Group 1 was composed of teeth with flattened surface. Groups 2, 3 & 4 were prepared of teeth with 2 mm ferrule. In the third group, everStick Net was applied above the ferrule. Group 5 was composed of teeth with large box type preparation. The root canals were enlarged, sandblasted and then surface treated with Stick resin for 5 min. Two types of FRC root canal posts were used. The crowns were prepared either with composite resin or with FC. A static load until failure was applied to the crowns at a 45 degrees angle. Failure modes were visually examined. ANOVA revealed that use of FRC-post and tooth preparation (p<0.001) had significant effect on fracture load of FRC-crown. The crowns made from only FC gave comparable fracture load to groups with FRC-post. No significant difference was found in load-bearing capacity between restorations reinforced with FRC net-substructure and those without (p>0.001). Chi-square test revealed that both, crown design and existence of FRC-post effected significantly fracture types (p<0.001). FC demonstrated similar load bearing capacity with restorations reinforced with FRC post. The presence of ferrule around the tooth increased the load bearing capacity significantly. EET - endodontically treated teeth; FRC - fiber-reinforced composite; semi-IPN - semi-interpenetrating network; CEJ - cementoenamel junction; FC - experimental short fiber composite; SiC - silicon carbide abrasive paper; N - newton; FEM - finite element method.The Open Dentistry Journal 01/2011; 5:58-65.
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ABSTRACT: The aim of the study was to evaluate the influence of fatigue and cementation mode on the fracture behaviour of endodontically treated bovine incisors restored with fiber-reinforced-composite (FRC) posts and crowns. Forty-eight endodontically treated incisors were restored with FRC posts, composite build-ups, and cast crowns. In 16 teeth, each of the posts were cemented conventionally with KetacCem (3M Espe) or adhesively with Panavia F (Kuraray) or RelyXUniCem (3M Espe). One-half of the specimens in each group were subjected to thermal cycling with 10,000 cycles at 5-55°C and mechanical aging, loading the specimens in 1,200,000 cycles with 50 N. Fracture resistance was determined by loading the specimens until fracture at an angle of 45°. The loading test showed that cementation mode and fatigue testing had an influence on the load bearing capability. Before fatigue testing no statistically significant differences between the different cementation modes could be detected. After fatigue testing, conventionally cemented FRC posts lead to statistically significant higher fracture loads compared to adhesively luted posts. Most specimens fractured in a favourable way, independent from the type of cementation.Dental Materials Journal 01/2011; 30(1):109-14. · 0.81 Impact Factor