title: Intermittent loading of teeth restored using quartz fiber, carbon-quartz fiber, and zirconium dioxide ceramic root canal posts.
abstract: OBJECTIVE
  The purpose of the investigation was to compare the performances of teeth restored with quartz fiber, carbon-quartz fiber, and zirconium-dioxide posts covered with all-ceramic crowns when subjected to a cyclic loading test performed in a wet environment.
  
  
  METHODS
  Forty single-rooted human lower premolars having similar dimensions were endodontically treated and mounted in acrylic resin blocks with a simulated periodontal ligament. The teeth were divided into three experimental groups and one control group. Post holes 8 mm long were prepared in the roots of the experimental groups in which quartz fiber, carbon-quartz fiber, and zirconium dioxide posts were cemented. In the control group, no posts were used. The crown buildup was made with composite resin. The teeth were covered with all-ceramic crowns and intermittently loaded at an angle of 45 degrees to the long axis of the tooth at a frequency of two loads per second.
  
  
  RESULTS
  Only one failure (root fracture + post fracture) was observed in each of the fiber post groups, while in the zirconium dioxide post group, six failures were observed (one crown fracture and 5 root fractures + post fractures). The Kaplan-Meier analysis of the three experimental groups showed that the survival rate of zirconium dioxide posts was significantly lower than that of both types of fiber post. All the experimental groups showed a survival rate higher than that of the control group.
  
  
  CONCLUSIONS
  Fiber posts reduced to a minimum the risk of root fractures of teeth restored with composite cores and Empress crowns under the present experimental conditions (intermittent loading in a wet environment).
authors.affiliation: Department of Endodontics, University of Siena, Italy.
authors.forename: F
authors.initials: F
authors.lastname: Mannocci
authors.forename: M
authors.initials: M
authors.lastname: Ferrari
authors.forename: T F
authors.initials: TF
authors.lastname: Watson
mesh_terms: D000538:Aluminum Silicates; D001641:Bicuspid; D002244:Carbon; D000077482:Carbon Fiber; D003188:Composite Resins; D003764:Dental Materials; D003776:Dental Porcelain; D019232:Dental Restoration Failure; D004548:Elasticity; D006801:Humans; D008334:Mandible; D008422:Materials Testing; D011176:Post and Core Technique; D011791:Quartz; D016019:Survival Analysis; D014082:Tooth Fractures / Q000517:prevention & control; D014092:Tooth Root / Q000293:injuries; D015040:Zirconium
chemical_list: D000538:Aluminum Silicates; D000077482:Carbon Fiber; D003188:Composite Resins; D003764:Dental Materials; C075815:IPS-Empress ceramic; D003776:Dental Porcelain; D011791:Quartz; D002244:Carbon; D015040:Zirconium; C028541:zirconium oxide