title: Influence of periodontal ligament simulation on bond strength and fracture resistance of roots restored with fiber posts.
abstract: OBJECTIVE
  Considering that periodontal ligament simulation may influence the stress distribution over teeth restored with intraradicular retainers, this study aimed to assess the combined effect of mechanical cycling and periodontal ligament simulation on both the bond strength between fiber posts and root dentin and the fracture resistance of teeth restored using glass fiber posts.
  
  
  METHODS
  Ninety roots were randomly distributed into 3 groups (n=10) (C-MC: control; P-MC: polyether; AS-MC: addition silicone) to test bond strength and 6 groups (n=10) (C: control; P: polyether; AS: addition silicone, without mechanical cycling, and C-MC, P-MC and AS-MC with mechanical cycling) to test fracture strength, according to the material used to simulate the periodontal ligament. For the bond strength test, fiber posts were cemented, cores were built, mechanical cycling was applied (2×10(6) cycles, 88 N, 2.2 Hz, and 45º incline), and the teeth cut into 3 slices (2 mm), which were then subjected to the push-out test at 1 mm/min. For the fracture strength test, fiber posts were cemented, cores were built, and half of the groups received mechanical cycling, followed by the compressive strength (45° to the long axis and 1 mm/min) performed on all groups.
  
  
  RESULTS
  Periodontal ligament simulation did not affect the bond strength (p=0.244) between post and dentin. Simulation of periodontal ligament (p=0.153) and application of mechanical cycling (p=0.97) did not affect fracture resistance.
  
  
  CONCLUSIONS
  The materials used to simulate the periodontal ligament did not affect fracture or bond strength, therefore periodontal ligament simulation using the tested materials could be considered optional in the conditions of the study.
authors.affiliation: Department of Restorative Dentistry, School of Dentistry, Federal University of Santa Maria, Santa Maria, RS, Brazil.
authors.forename: Ana Maria Estivalete
authors.initials: AM
authors.lastname: Marchionatti
authors.affiliation: Department of Restorative Dentistry, School of Dentistry, Federal University of Santa Maria, Santa Maria, RS, Brazil.
authors.forename: Vinícius Felipe
authors.initials: VF
authors.lastname: Wandscher
authors.affiliation: Department of Restorative Dentistry, School of Dentistry, Federal University of Santa Maria, Santa Maria, RS, Brazil.
authors.forename: Juliana
authors.initials: J
authors.lastname: Broch
authors.affiliation: Department of Restorative Dentistry, School of Dentistry, Federal University of Pelotas, Pelotas, RS, Brazil.
authors.forename: César Dalmolin
authors.initials: CD
authors.lastname: Bergoli
authors.affiliation: Department of Stomatology, School of Dentistry, Federal University of Santa Maria, Santa Maria, RS, Brazil.
authors.forename: Juliana
authors.initials: J
authors.lastname: Maier
authors.affiliation: Department of Restorative Dentistry, School of Dentistry, Federal University of Santa Maria, Santa Maria, RS, Brazil.
authors.forename: Luiz Felipe
authors.initials: LF
authors.lastname: Valandro
authors.affiliation: Department of Restorative Dentistry, School of Dentistry, Federal University of Santa Maria, Santa Maria, RS, Brazil.
authors.forename: Osvaldo Bazzan
authors.initials: OB
authors.lastname: Kaizer
mesh_terms: D000818:Animals; D002417:Cattle; D003188:Composite Resins / Q000737:chemistry; D019245:Compressive Strength; D001840:Dental Bonding / Q000379:methods*; D019232:Dental Restoration Failure; D003799:Dental Stress Analysis; D005898:Glass / Q000737:chemistry; D008422:Materials Testing; D008855:Microscopy, Electron, Scanning; D010513:Periodontal Ligament; D011176:Post and Core Technique; D011897:Random Allocation; D015203:Reproducibility of Results; D013314:Stress, Mechanical; D013499:Surface Properties; D013718:Tensile Strength; D014082:Tooth Fractures
chemical_list: D003188:Composite Resins; C009753:fiberglass