title: Fracture strength of teeth with flared root canals restored with glass fibre posts.
abstract: OBJECTIVE
  To investigate the fracture strength and pattern of failure of teeth with weakened roots reconstructed by different procedures.
  
  
  METHODS
  In an in vitro study root posts were placed in 50 endodontically treated canines, divided into 5 groups (n=10) as follows: cast metallic post; glass fibre post with smaller diameter than the root canal; glass fibre post with smaller diameter than the root canal + glass fibre strips; glass fibre post with smaller diameter than the root canal + accessory glass fibre posts; anatomical post (glass fibre post with smaller diameter than the root canal, relined with low viscosity composite resin). Posts were luted with resin cement and the coronal portion of posts was constructed with composite resin. Metallic crowns were cemented on the posts. Specimens were submitted to compressive load in a universal testing machine. Fracture strength values of each group were compared.
  
  
  RESULTS
  Fracture strength values were for Groups 1-5 respectively: 1087.06; 745.69; 775.41; 920.64; 876.12kgf, with significant differences between Groups 1 and 2 and between Groups 1 and 3 (p<0.05). Observed patterns of fracture were: Group 1 - 100% of roots fractured; Groups 2 and 4 - variable fracture modes; Group 3 - 60% of fractures occurred in the cervical root third; Group 5 - 50% of failures occurred in the coronal portion of the post.
  
  
  CONCLUSIONS
  The fracture strength of teeth with cast metallic posts, teeth with anatomical posts or teeth with glass fibre posts combined with accessory posts was similar. All teeth restored with cast metallic posts presented fractures and were unfavourable to maintenance of the remaining tooth structure. Teeth with fibre posts (Groups 2 to 5) presented variable fracture modes; however, the maximum percentage of unfavourable fractures was 30%.
authors: Gerson
authors: G
authors: Bonfante
authors: Osvaldo Bazzan
authors: OB
authors: Kaizer
authors: Luiz Fernando
authors: LF
authors: Pegoraro
authors: Accácio Lins
authors: AL
authors: do Valle
mesh_terms: D002858:Chromium Alloys / Q000737:chemistry; D003188:Composite Resins / Q000737:chemistry; D019245:Compressive Strength; D003442:Crowns; D003722:Dental Alloys / Q000737:chemistry; D003764:Dental Materials / Q000737:chemistry*; D017267:Dental Prosthesis Design; D003786:Dental Pulp Cavity / Q000503:physiopathology*; D003799:Dental Stress Analysis; D005898:Glass / Q000737:chemistry*; D006801:Humans; D008422:Materials Testing; D018583:Pliability; D011176:Post and Core Technique / Q000295:instrumentation*; D019279:Resin Cements / Q000737:chemistry; D018915:Root Canal Preparation / Q000379:methods; D013314:Stress, Mechanical; D013499:Surface Properties; D014082:Tooth Fractures / Q000503:physiopathology*; D014092:Tooth Root / Q000293:injuries / Q000503:physiopathology
chemical_list: D002858:Chromium Alloys; D003188:Composite Resins; D003722:Dental Alloys; D003764:Dental Materials; D019279:Resin Cements; C009753:fiberglass