title: [Fracture resistence force of the cement-expanded composite screw post-core system].
abstract: OBJECTIVE
  This is a study comparing the effects of different post designs on the fracture resistence.
  
  
  METHODS
  Twenty-seven simulated tooth roots made of polymethyl methacrylate (PMMA) were divided into three groups, then the cement-expanded composite screw post-core system (CECSP), cement screw post-core system (CSP) and cast metal post-core system (CMP) were manufactured. The root and post-core system was compressed by the speed of 1 mm/min on the Instron 4302 and the fracture resistence force was recorded.
  
  
  RESULTS
  Statistical analysis of the measured values showed the fracture resistence force of CECSP and CMP to be significantly greater than that of CSP (P < 0.05), but there was no significant difference between the fracture resistence force of CECSP and CMP (P > 0.05).
  
  
  CONCLUSIONS
  The fracture mechanical properties of CECSP are much better than those of cement screw post-core system and are similar to cast metal post-core system. Therefore, it is possible to find a new way for restoration of endodontally treated teeth.
authors.affiliation: Deparment of Prosthodontics, West China Shcool of Stomatology, Sichuan University, Chengdu 610041, China.
authors.forename: Xin-min
authors.initials: XM
authors.lastname: Chen
authors.forename: Nian-bin
authors.initials: NB
authors.lastname: Wang
authors.forename: Yan
authors.initials: Y
authors.lastname: Yang
authors.forename: Tao
authors.initials: T
authors.lastname: He
authors.forename: Xiao-hong
authors.initials: XH
authors.lastname: Wu
authors.forename: Gul-ju
authors.initials: GJ
authors.lastname: Zhang
authors.forename: Lin
authors.initials: L
authors.lastname: Niu
authors.forename: Ping-ping
authors.initials: PP
authors.lastname: Li
mesh_terms: D003188:Composite Resins; D003442:Crowns; D019232:Dental Restoration Failure; D003799:Dental Stress Analysis; D006801:Humans; D011176:Post and Core Technique; D014082:Tooth Fractures; D014092:Tooth Root
chemical_list: D003188:Composite Resins