title: [The effect of rehabilitation of flared root canal on the fracture resistance of root and post-core system].
abstract: OBJECTIVE
  To assess the effect of rehabilitation of flared root canal on the fracture resistance of root and post-core system.
  
  
  METHODS
  Thirty-two simulated tooth roots made of polymethyl methacrylate were divided into 4 groups, including the normal root canal group and 3 flared root canal groups. One flared root canal group was rehabilitated by light-cared composite, another group was rehabilitated by amalgam, and the third flared root conal group was not treated. Casting post and core restored every simulated tooth root. Each specimen was embedded in acrylic resin and then fixed in a special jig on the universal load-testing machine. A compressive load was applied at a 90-degree angle to the long axis of the core until fracture, at a crosshead speed of 1 mm/min; the maximum of load was recorded.
  
  
  RESULTS
  The means of load in normal root canal group, light-cared composite rehabilitated group, amalgam rehabilitated group, not treated group were 202.92 N, 194.60 N, 146.89 N, 142.09 N. It was shown that the load of normal root canal group is significantly greater than the load of not-treated group (P < 0.01); the light-cared composite rehabilitated group is significantly stronger than the not-treated group (P < 0.01), but there is no significant difference between the light-cared composite rehabilitated group and normal root canal group, and no significant difference between the amalgam rehabilitated group and not-treated group (P > 0.05).
  
  
  CONCLUSIONS
  The rehabilitation of flared root canal using suitable material not only changes the shape of root canal, but also increases the fracture resistance of root canal because of its thicker and stronger root canal wall which obviously improves the fracture resistance of post and core.
authors.affiliation: Department of Prosthodontics, West China School of Stomatology, Sichuan University, Chengdu 610041, China.
authors.forename: Rui
authors.initials: R
authors.lastname: Hou
authors.forename: Xinming
authors.initials: X
authors.lastname: Chen
authors.forename: Junhua
authors.initials: J
authors.lastname: Wu
authors.forename: Huijun
authors.initials: H
authors.lastname: Chang
mesh_terms: D000180:Acrylic Resins; D003188:Composite Resins; D003442:Crowns; D003776:Dental Porcelain / Q000737:chemistry; D017267:Dental Prosthesis Design; D003786:Dental Pulp Cavity / Q000473:pathology; D019232:Dental Restoration Failure; D003799:Dental Stress Analysis / Q000295:instrumentation; D006801:Humans; D011140:Polyurethanes; D011176:Post and Core Technique; D018915:Root Canal Preparation / Q000379:methods*; D014082:Tooth Fractures / Q000517:prevention & control*; D019553:Tooth, Nonvital / Q000150:complications*
chemical_list: D000180:Acrylic Resins; C029012:Composite Dental Resin; D003188:Composite Resins; D011140:Polyurethanes; D003776:Dental Porcelain