title: Reinforcement effect of polyethylene fibre in root-filled teeth: comparison of two restoration techniques.
abstract: OBJECTIVE
  To compare in vitro two different fibre placement techniques on reinforcement of root-filled molar teeth with mesio-occluso-distal (MOD) cavities.
  
  
  METHODS
  Fifty sound extracted human mandibular molars were used (n = 10). Group 1 served as control. From group 2-5, endodontic access and standard MOD cavities were prepared. Following root canal treatment, group 2 was kept unrestored. In groups 3 and 4, the teeth were restored with composite resin (AP-X; Kuraray, Japan). A groove was prepared on occlusal surface of the finished restorations in group 4 from buccal to lingual direction. Polyethylene woven fibre (Ribbond; Seattle, WA, USA) was inserted in the groove in combination with flowable resin that was cured for 20 s and covered with composite resin. Cavity surfaces were covered with flowable resin in group 5, and polyethylene fibre was placed into the bed of resin in a buccal to lingual direction before the composite restoration was placed. All specimens were stored in 100% humidity at 37 degrees C for 24 h. Compressive loading of the teeth was performed by a universal testing machine at a crosshead speed of 0.5 mm min(-1) until failure. The data were recorded in Newton and submitted to anova and Tukey post hoc test.
  
  
  RESULTS
  The mean load necessary to fracture the samples in each group was: G1: 1671.57 +/- 131.54(a); G2: 375.21 +/- 34.30(b); G3: 749.47 +/- 124.54(c); G4: 1224.36 +/- 132.17(d); G5: 926.88 +/- 118.28(e). Different superscript letters demonstrate significant difference between groups.
  
  
  CONCLUSIONS
  Polyethylene fibre use over or under MOD composite restorations significantly increased fracture strength. However, when the fibre was placed on the occlusal surface of the restoration in buccal to lingual direction, significantly higher fracture resistance was observed.
authors.affiliation: Department of Endodontics, Faculty of Dentistry, Selcuk University, Konya, Turkey.
authors.forename: S
authors.initials: S
authors.lastname: Belli
authors.forename: A
authors.initials: A
authors.lastname: Erdemir
authors.forename: C
authors.initials: C
authors.lastname: Yildirim
mesh_terms: D003188:Composite Resins / Q000737:chemistry; D003737:Dental Cavity Preparation / Q000145:classification; D003764:Dental Materials / Q000737:chemistry*; D003793:Dental Restoration, Permanent / Q000379:methods*; D003799:Dental Stress Analysis; D006801:Humans; D008422:Materials Testing; D008689:Methacrylates / Q000737:chemistry; D008963:Molar; D011095:Polyethylenes / Q000737:chemistry*; D019279:Resin Cements / Q000737:chemistry; D012390:Root Canal Therapy; D013314:Stress, Mechanical; D013499:Surface Properties; D014082:Tooth Fractures / Q000503:physiopathology
chemical_list: C112828:Clearfil AP-X; C438313:Clearfil SE Bond; D003188:Composite Resins; D003764:Dental Materials; D008689:Methacrylates; D011095:Polyethylenes; C409388:Protect Liner F; C084063:RIBBOND; D019279:Resin Cements