title: Fracture resistance of endodontically treated teeth restored with three different prefabricated esthetic posts.
abstract: OBJECTIVE
  This study was undertaken to evaluate the role of composition of prefabricated esthetic posts in fracture resistance of endodontically treated teeth in vitro.
  
  
  METHODS
  Thirty human, single-rooted teeth (maxillary central incisors and canines) with similar root dimensions, extracted for therapeutic reasons, were used in this study. The crowns were removed below the cementoenamel junction to obtain a standard root length of 17 mm. The roots were endodontically treated following the conventional manual technique and randomly assigned to three groups (n = 10) according to the post used: Aestheti-Post, Bisco, Schaumberg, Illinois; FibreKor Post, Jeneric/Pentron, Wallingford, Connecticut; and CosmoPost, Ivoclar Vivadent, Schaan, Liechtenstein. The root canals were rendered patent, and the root preparations were standardized through flaring with the manufacturers' drills included in the respective kits. The posts were cemented with an adhesive system and a resin cement (All-Bond 2 and C&B, Bisco, respectively), according to the manufacturers' directions. Composite resin (Tetric Ceram, Ivoclar Vivadent) crowns were built up using a preformed polyester matrix, and the specimens were mounted in metallic rings with cold-cure acrylic resin and kept in saline solution at 4 degrees C for 24 hours. Fracture resistance was then determined using an EMIC DL-2000 universal testing machine. The crosshead speed was 0.5 mm/min with the 45-degree compressing load at the middle third of the crown. Data were analyzed using one-way analysis of variance and Tukey's test (p < or = .001).
  
  
  RESULTS
  Mean fracture resistance was as follows: Aestheti-Post, 83.5 kgf; FibreKor Post, 85.7 kgf; and CosmoPost, 36.5 kgf. The fracture strength of CosmoPost was significantly lower than that of the other posts. Teeth restored with CosmoPost had post fractures, and in three specimens, those were associated with root fractures. Teeth restored with the other two posts presented fractures on the composite crowns.
authors.affiliation: Division of Operative Dentistry, Department of Prosthodontics, Pontifical Catholic University of Rio Grande do Sul School of Dentistry, Porto Alegre, RS, Brazil.
authors.forename: Paulo C A
authors.initials: PC
authors.lastname: Maccari
authors.forename: Ewerton N
authors.initials: EN
authors.lastname: Conceição
authors.forename: Mauro F
authors.initials: MF
authors.lastname: Nunes
mesh_terms: D000704:Analysis of Variance; D002244:Carbon; D000077482:Carbon Fiber; D003188:Composite Resins; D019245:Compressive Strength; D003481:Cuspid; D019232:Dental Restoration Failure; D003799:Dental Stress Analysis; D004548:Elasticity; D005898:Glass; D006801:Humans; D007180:Incisor; D008422:Materials Testing; D011176:Post and Core Technique; D011897:Random Allocation; D019553:Tooth, Nonvital; D015040:Zirconium
chemical_list: D000077482:Carbon Fiber; D003188:Composite Resins; C009753:fiberglass; D002244:Carbon; D015040:Zirconium; C028541:zirconium oxide