title: [Fracture resistance of thin-walled teeth restored with different post and core materials].
abstract: OBJECTIVE
  To discuss the selection of appropriate post and core materials in order to obtain better fracture resistance for thin-walled teeth.
  
  
  METHODS
  Ninety maxillary incisors were endodontically treated and the crowns were cut off. Then they were randomly divided into 9 groups. The teeth in the first 4 groups were restored with cast (A1.3 and A1.6) and fiber (B1.3 and B1.6) posts of 1.3 and 1.7 mm diameters. The teeth in the other 5 groups were enlarged to simulate the 1 mm thin-walled teeth and restored with cast (C) and fiber posts. The fiber posts were reconstructed and cemented with Unicem (D1.3 and D1.6) and ParaCore (E1.3 and E1.6). All teeth were restored with full crown, and the fracture resistance and fracture mode were analysed. Statistical analysis was carried out using SPSS 16.0 software package.
  
  
  RESULTS
  Largest fracture resistance values (610.2 ± 45.6) N were found in Group A1.3 of ordinary root canals, and no significant difference (P>0.05) existed between Group A1.3, A1.6 and B1.3, B1.6. Group C received the largest fracture resistance value(584.5 ± 121.2) N in thin-walled root canals, and fiber posts reconstructed with ParaCore cement could increase fracture resistance [E1.3,(420.6 ± 95.7) N; E1.6,(517.9 ± 67.2) N], which was significant different compared with D1.3 and D1.6 (P<0.05), but similar to B1.3 and B1.6 in ordinary root canals.
  
  
  CONCLUSIONS
  The root can be better preserved by fiber post and the fracture resistance is not affected by the posts with diameters of 1.3 mm and 1.6 mm. The fracture resistance of teeth can be enhanced by reconstruction of root canals with Paracore.
authors.affiliation: Department of Stomatology, Shangyu People's Hospital of Shaoxing. Shaoxing 312300, Zhejiang Province, China.E-mail:wmeizhou@gmial.com.
authors.forename: Wen-mei
authors.initials: WM
authors.lastname: Zhou
authors.forename: Guo-wei
authors.initials: GW
authors.lastname: Huang
mesh_terms: D003188:Composite Resins; D003442:Crowns; D003738:Dental Cements; D003799:Dental Stress Analysis; D005899:Glass Ionomer Cements; D006801:Humans; D007180:Incisor; D011176:Post and Core Technique; D014082:Tooth Fractures; D019553:Tooth, Nonvital
chemical_list: D003188:Composite Resins; D003738:Dental Cements; D005899:Glass Ionomer Cements