title: Fracture susceptibility of endodontically treated teeth.
abstract: OBJECTIVE
  To assess the influence of cervical preparation on fracture susceptibility of roots.
  
  
  METHODS
  During root canal instrumentation, the cervical portions were prepared with different taper instruments: I: no cervical preparation; II: #30/.08; III: #30/.10; IV: #70/.12. The specimens were sealed with the following filling materials (n = 8), A: unfilled; B: Endofill/gutta-percha; C: AH Plus/gutta-percha; D: Epiphany SE/Resilon. For the fracture resistance test, a universal testing machine was used at 1 mm per minute.
  
  
  RESULTS
  anova demonstrated difference (P < 0.05) between taper instruments with a higher value for group I (205.3 ± 77.5 N) followed by II (185.2 ± 70.8 N), III (164.8 ± 48.9 N), and IV (156.7 ± 41.4 N). There was no difference (P > 0.05) between filling materials A (189.1 ± 66.3 N), B (186.3 ± 61.0 N), C (159.7 ± 69.9 N), and D (176.9 ± 55.2 N).
  
  
  CONCLUSIONS
  Greater cervical wear using a #70/.12 file increased the root fracture susceptibility, and the tested filling materials were not able to restore resistance.
authors.affiliation: School of Dentistry, University of Ribeirão Preto, Ribeirão Preto, SP, Brazil.
authors.forename: Caroline
authors.initials: C
authors.lastname: Zamin
authors.forename: Yara Terezinha Correa
authors.initials: YT
authors.lastname: Silva-Sousa
authors.forename: Aline Evangelista
authors.initials: AE
authors.lastname: Souza-Gabriel
authors.forename: Danielle Furtado
authors.initials: DF
authors.lastname: Messias
authors.forename: Manoel Damião
authors.initials: MD
authors.lastname: Sousa-Neto
mesh_terms: D000704:Analysis of Variance; D003799:Dental Stress Analysis; D006801:Humans; D007180:Incisor / Q000601:surgery; D012387:Root Canal Filling Materials / Q000737:chemistry*; D012389:Root Canal Obturation / Q000379:methods*; D018915:Root Canal Preparation / Q000295:instrumentation*; D014082:Tooth Fractures / Q000145:classification / Q000209:etiology* / Q000517:prevention & control; D014092:Tooth Root / Q000293:injuries*; D019553:Tooth, Nonvital / Q000150:complications*
chemical_list: D012387:Root Canal Filling Materials