title: Bending resistance of unit cast posts-and-cores compared with noble posts following molten cast core attachment.
abstract: The aim of this in vitro study was to evaluate the bending resistance of unit cast posts-and-cores (UPC) and prefabricated high noble posts with cast-on cores. Tapered posts (ER post-restoring system) of three sizes in diameter (ISO 50, 90, 110) were investigated: UPC were cast of three different alloys (Au-Pt-Pd, Au-Ag-Pt, Co-Cr-Mo). Also, prefabricated tapered noble posts (Heraplat and Pt-Ir) were cast over with metal cores of the different alloys. Prefabricated titanium posts of each size were precision fit into the central core channels of the Co-Cr-Mo cores to serve as control specimens. The 0.2% yield strengths (R(0.2)) of all specimens were tested on a universal testing machine. One-way and three-way anova and Bonferroni-Dunn's multiple comparison tests were performed for the statistical analysis. The mean bending resistance R(0.2) of the unit cast posts-and-cores was 45 +/- 4-46 +/- 5 N for ISO 50 (control group: 54 +/- 3 N), 91 +/- 9-93 +/- 7 N for ISO 90 (control group: 117 +/- 11 N) and 115 +/- 13-130 +/- 12 N for ISO 110 (control group: 141 +/- 12 N). Except for the Au-Pt-Pd UPC of ISO 110, the yield strengths of the control groups were significantly superior to all unit cast alloy combinations (P < 0.05). Significantly lower bending resistance was found for Co-Cr-Mo cores cast over Heraplat and Pt-Ir posts compared with the corresponding Heraplat/Au-Ag-Pt, Heraplat/Au-Pt-Pd and Pt-Ir/Au-Ag-Pt posts-and-cores.
authors.affiliation: Department of Prosthetic Dentistry, School of Oral Medicine, University of Cologne, Germany. peter.pfeiffer@uni-koeln.de
authors.forename: P
authors.initials: P
authors.lastname: Pfeiffer
authors.forename: P
authors.initials: P
authors.lastname: Schmage
authors.forename: A
authors.initials: A
authors.lastname: Schulz
authors.forename: I
authors.initials: I
authors.lastname: Nergiz
mesh_terms: D003722:Dental Alloys; D003799:Dental Stress Analysis; D006801:Humans; D011176:Post and Core Technique / Q000295:instrumentation*; D013314:Stress, Mechanical; D014025:Titanium
chemical_list: D003722:Dental Alloys; D014025:Titanium