title: Similar influence of stabilized alkaline and neutral sodium hypochlorite solutions on the fracture resistance of root canal-treated bovine teeth.
abstract: BACKGROUND
  Stabilizing sodium hypochlorite (NaOCl) at an alkaline pH is proposed to increase solution stability and tissue dissolution ability; however, a reduction on the flexural strength of dentin discs has been found to be a side effect. This study sought to determine whether a stabilized alkaline NaOCl reduces the fracture resistance of root canal-treated bovine teeth after root canal preparation compared with a neutral solution counterpart.
  
  
  METHODS
  The 4 anterior incisors were removed from 20 mandibular bovine jaws, and each 1 was randomly assigned to 1 of 4 groups (20 teeth each). Teeth were prepared with a sequence of 6 K-type files. The following experimental groups received a different irrigation regimen: G1: distilled water (negative control), G2: 5% NaOCl at a pH of 7.2, and G3: 5% NaOCl at a pH of 12.8; in the positive control group (G4), teeth remained untreated. The time of contact and volume of solution were carefully standardized. After bone and periodontal ligament simulation, teeth were subjected to a fracture resistance test.
  
  
  RESULTS
  A significant difference was observed among the 4 groups tested (analysis of variance, P < .05). The 5% NaOCl groups (G2 and G3) presented significantly lower resistance to fracture than the control (G1 and G4) (Tukey test, P < .05). Both NaOCl solutions similarly reduced the fracture resistance at approximately 30% (Tukey test, P > .05). No differences were observed between positive and negative control groups (Tukey test, P > .05).
  
  
  CONCLUSIONS
  Stabilized alkaline and neutral NaOCl solutions similarly reduced the fracture resistance of root canal-treated bovine teeth by about 30%.
authors.affiliation: Department of Dentistry II, Federal University of Maranhão, São Luis, Brazil. Electronic address: erickmsouza@uol.com.br.
authors.forename: Erick Miranda
authors.initials: EM
authors.lastname: Souza
authors.affiliation: Private Practice, São Luis, Brazil.
authors.forename: Amanda Martins
authors.initials: AM
authors.lastname: Calixto
authors.affiliation: Private Practice, São Luis, Brazil.
authors.forename: Camila Nara E
authors.initials: CN
authors.lastname: Lima
authors.affiliation: Department of Endodontics, Federal University of Pelotas, Pelotas, Brazil.
authors.forename: Fernanda Geraldo
authors.initials: FG
authors.lastname: Pappen
authors.affiliation: Department of Endodontics, Grande Rio University, Rio de Janeiro, Brazil.
authors.forename: Gustavo
authors.initials: G
authors.lastname: De-Deus
mesh_terms: D000468:Alkalies; D000818:Animals; D002417:Cattle; D003786:Dental Pulp Cavity / Q000187:drug effects; D003799:Dental Stress Analysis / Q000295:instrumentation; D003804:Dentin / Q000187:drug effects; D006863:Hydrogen-Ion Concentration; D008422:Materials Testing; D011897:Random Allocation; D012388:Root Canal Irrigants / Q000737:chemistry* / Q000494:pharmacology; D018915:Root Canal Preparation / Q000295:instrumentation / Q000379:methods*; D012973:Sodium Hypochlorite / Q000737:chemistry* / Q000494:pharmacology; D013314:Stress, Mechanical; D007507:Therapeutic Irrigation / Q000379:methods; D013997:Time Factors; D014082:Tooth Fractures / Q000503:physiopathology*; D019553:Tooth, Nonvital / Q000503:physiopathology*; D014867:Water / Q000737:chemistry
chemical_list: D000468:Alkalies; D012388:Root Canal Irrigants; D014867:Water; D012973:Sodium Hypochlorite
keywords: Alkaline NaOCl; bovine teeth; fracture resistance of endodontically treated teeth