title: Scanning electron microscopy analysis of two methods of root-end preparation.
abstract: OBJECTIVE
  This study evaluated changes in dental tissues of the apical third after root-end preparation.
  
  
  METHODS
  Sixty permanent single-rooted human teeth were used after apicectomy at 90 degrees to the long axis of the tooth. Crown removal was performed with a double-faced diamond disk, on a straight handpiece, and specimen standard length was set at 8 mm. Root-end cavities were prepared with an ultrasound system in 30 teeth (G1); in the other teeth, the cavities were prepared with a bur using a contra-angle and micro-handpiece (G2). The width of the root-end cavity was the diameter of the tip or bur, and its depth was 3 mm. Each group was divided into two subgroups with 15 teeth each; 37% phosphoric acid was applied to specimens in subgroups G1B and G2B. All specimens were photographed under scanning electron microscopy. Images were evaluated descriptively and data were compared for fractures, smear layer, uniform inner surface, regular edges, and whether root-end preparation including the whole foramen. A chi-square test and the kappa index were used to analyze results statistically.
  
  
  RESULTS
  Only two variables, uniform inner surface and regular edge, varied according to the method used (bur or ultrasound). The presence of smear layer was associated with the use of phosphoric acid.
  
  
  CONCLUSIONS
  Both methods seemed to be adequate for use in endodontic surgeries.
authors.affiliation: Specialization Program in Surgery and Maxillofacial Surgery and Trauma, School of Dentistry, Pontifícia Universidade Católica do Rio Grande do Sul, Porto Alegre, RS, Brazil.
authors.forename: C
authors.initials: C
authors.lastname: De Moraes Izquierdo
authors.forename: J F
authors.initials: JF
authors.lastname: Duarte Moraes
authors.forename: I
authors.initials: I
authors.lastname: Hellwig
authors.forename: M
authors.initials: M
authors.lastname: Gerhardt De Oliveira
authors.forename: J B
authors.initials: JB
authors.lastname: Blessmann Weber
mesh_terms: D006801:Humans; D008855:Microscopy, Electron, Scanning; D019246:Tooth Preparation / Q000379:methods*; D014092:Tooth Root / Q000648:ultrastructure*