title: Influence of irrigant, dowel type, and root-reinforcing material on fracture resistance of thin-walled endodontically treated teeth.
abstract: OBJECTIVE
  Unresolved controversy exists concerning the optimum restorative material to reinforce the thin-walled roots of endodontically treated teeth to improve their fracture resistance under occlusal load. This study evaluated the effectiveness of irrigant, dowel type, and root-reinforcing material on the fracture resistance of thin-walled endodontically treated teeth.
  
  
  METHODS
  The root canals of 140 maxillary central incisors were enlarged and equally divided into seven groups according to the canal irrigant: no irrigant (control), 5% hydrogen peroxide, 5% sodium hypochlorite, a combination of 5% hydrogen peroxide and sodium hypochlorite, 15% ethylenediaminotetraacetic acid (EDTA), 10% lactic acid, or 20% lactic acid. Within each group, root canals were lined with composite resin (PermaFlo) or glass ionomer cement (Fuji II LC). A light-transmitting plastic dowel (Luminex) was used to create space for a quartz fiber-reinforced dowel (Aestheti Post) or a titanium alloy dowel (ParaPost XH) and to cure the restorative materials. Following dowel cementation and restoration of the roots with composite core, the teeth were submitted to fracture resistance testing, and data were analyzed with 3-way ANOVA followed by Ryan-Einot-Gabriel-Welsch Multiple Range Test (α= 0.05).
  
  
  RESULTS
  Fracture resistance values were significantly different among irrigants, restorative materials, and their interaction (p < 0.001); however, the dowel type was not significantly different (p= 0.51).
  
  
  CONCLUSIONS
  Thin-walled roots that had the smear layer removed with lactic acid and that were then lined with composite resin had a higher fracture resistance.
authors.affiliation: College of Dentistry, University of Tanta, Egypt. ayadmf@hotmail.com
authors.forename: Mohamed F
authors.initials: MF
authors.lastname: Ayad
authors.forename: Salma A
authors.initials: SA
authors.lastname: Bahannan
authors.forename: Stephen F
authors.initials: SF
authors.lastname: Rosenstiel
mesh_terms: D001696:Biomechanical Phenomena; D003188:Composite Resins / Q000737:chemistry*; D003722:Dental Alloys / Q000737:chemistry; D003764:Dental Materials / Q000737:chemistry*; D003786:Dental Pulp Cavity / Q000503:physiopathology*; D003799:Dental Stress Analysis / Q000295:instrumentation; D003804:Dentin / Q000503:physiopathology; D004492:Edetic Acid / Q000627:therapeutic use; D005899:Glass Ionomer Cements / Q000737:chemistry*; D006171:Gutta-Percha / Q000627:therapeutic use; D006801:Humans; D006861:Hydrogen Peroxide / Q000627:therapeutic use; D007180:Incisor / Q000503:physiopathology; D019344:Lactic Acid / Q000627:therapeutic use; D008422:Materials Testing; D008855:Microscopy, Electron, Scanning; D011176:Post and Core Technique / Q000295:instrumentation*; D011791:Quartz / Q000737:chemistry; D012117:Resins, Synthetic / Q000737:chemistry; D012387:Root Canal Filling Materials / Q000627:therapeutic use; D012388:Root Canal Irrigants / Q000627:therapeutic use*; D018915:Root Canal Preparation / Q000295:instrumentation / Q000379:methods*; D012973:Sodium Hypochlorite / Q000627:therapeutic use; D013314:Stress, Mechanical; D014025:Titanium / Q000737:chemistry; D014082:Tooth Fractures / Q000503:physiopathology*; D019553:Tooth, Nonvital / Q000503:physiopathology*
chemical_list: D003188:Composite Resins; D003722:Dental Alloys; D003764:Dental Materials; C079765:Fuji II LC cement; D005899:Glass Ionomer Cements; C423507:PermaFlow; D012117:Resins, Synthetic; D012387:Root Canal Filling Materials; D012388:Root Canal Irrigants; D011791:Quartz; D019344:Lactic Acid; D006171:Gutta-Percha; D004492:Edetic Acid; D006861:Hydrogen Peroxide; D014025:Titanium; D012973:Sodium Hypochlorite