title: The effect of spreader size on fracture resistance of maxillary incisor roots.
abstract: OBJECTIVE
  To assess the effect of spreader size used during cold lateral compaction of gutta-percha on fracture resistance of roots in maxillary incisor teeth.
  
  
  METHODS
  The crowns of 50 human maxillary incisor teeth having no carious lesions, no fracture or crazing were resected 2 mm coronal to the cemento-enamel junction. The root canals of the teeth were prepared as follows: Group 1: No canal preparation. Group 2: Preparation using the stepback technique to a size 40 master apical file. Group 3: Canal preparation to size 40 and filling with laterally compacted gutta-percha; the first spreader used was equal to size 40. Group 4: Same as group 3 except the first spreader was equal to size 35. Group 5: Same as group 3 except the first spreader was equal to size 25. For each root, a simulated periodontal ligament was prepared. The roots were than mounted in polyester resin and fractured vertically on a universal testing machine (Shimadzu, Tokyo, Japan). The fracture values of teeth were analysed using Kruskal-Wallis and Mann-Whitney U-tests (P = 0.05).
  
  
  RESULTS
  The uninstrumented group had the highest fracture resistance; instrumented, but unfilled roots, demonstrated the lowest resistance values (P = 0.009). There were no differences between the uninstrumented group and group 5 in which a size 25 spreader was used during filling. Use of spreaders larger than size 25 caused a significant reduction in fracture resistance of roots (P < 0.05).
  
  
  CONCLUSIONS
  Spreader size used during lateral compaction of gutta-percha can affect the fracture resistance of roots in extracted teeth.
authors.affiliation: Department of Restorative Dentistry & Endodontics, Ege University, Bornova, Izmir, Turkey.
authors.forename: B
authors.initials: B
authors.lastname: Pişkin
authors.forename: B
authors.initials: B
authors.lastname: Aydin
authors.forename: M
authors.initials: M
authors.lastname: Sarikanat
mesh_terms: D001729:Bismuth / Q000627:therapeutic use; D004338:Drug Combinations; D004867:Equipment Design; D006171:Gutta-Percha / Q000627:therapeutic use; D006801:Humans; D007180:Incisor / Q000503:physiopathology*; D008422:Materials Testing; D011145:Polyvinyls / Q000627:therapeutic use; D012387:Root Canal Filling Materials / Q000627:therapeutic use; D012389:Root Canal Obturation / Q000295:instrumentation* / Q000379:methods; D018915:Root Canal Preparation / Q000295:instrumentation / Q000379:methods; D013314:Stress, Mechanical; D013499:Surface Properties; D014082:Tooth Fractures / Q000503:physiopathology*; D014092:Tooth Root / Q000503:physiopathology*; D015034:Zinc Oxide / Q000627:therapeutic use
chemical_list: D004338:Drug Combinations; D011145:Polyvinyls; D012387:Root Canal Filling Materials; C014457:bismuth phosphate, copolymers of vinyl acetate, dichlorophen, propionyl-acetophenone, triethanolamine, vinyl chloride, vinylisobutyl ether, zinc oxide drug combination; D006171:Gutta-Percha; D015034:Zinc Oxide; D001729:Bismuth