title: Retreatment efficacy of gutta-percha removal using a clinical microscope and ultrasonic instruments: part I--an ex vivo study.
abstract: OBJECTIVE
  This study compared the efficacy of gutta-percha/sealer removal from endodontically treated extracted human teeth with and without the aid of a clinical operating microscope/ultrasonic instruments.
  
  
  METHODS
  Forty human extracted maxillary central incisors were prepared using a modified crown-down technique and filled with lateral compactation. Teeth were divided into 2 groups: group I, re-treated using a conventional technique with burs and solvent; and group II, re-treated using a conventional technique with burs and solvent plus clinical operating microscope/ultrasonic tips. Teeth were split longitudinally and photographed, and coded photos transfered to a computer workstation. Total canal space and remaining gutta-percha/sealer were quantified, and ratio of remaining filling material and root canal periphery was computed. Mean percentage of remaining gutta-percha/sealer in each group was compared using analysis of variance.
  
  
  RESULTS
  The average percentage of remaining gutta-percha/sealer was 25.21% in group I and 9.31% in group II, showing a statistically significant difference (P = .05).
  
  
  CONCLUSIONS
  The use of the dental operating microscope and ultrasonic tips removed the filling material from root canal walls better, but all examined teeth, in both groups, had remaining filling material on canal walls.
authors.affiliation: Center for Dental Research, São Leopoldo Mandic, Campinas, Brazil.
authors.forename: Jose Eduardo
authors.initials: JE
authors.lastname: de Mello Junior
authors.forename: Rodrigo Sanches
authors.initials: RS
authors.lastname: Cunha
authors.forename: Carlos Eduardo da Silveira
authors.initials: CE
authors.lastname: Bueno
authors.forename: Mario Luis
authors.initials: ML
authors.lastname: Zuolo
mesh_terms: D003786:Dental Pulp Cavity / Q000473:pathology*; D006171:Gutta-Percha / Q000627:therapeutic use*; D006801:Humans; D007091:Image Processing, Computer-Assisted; D008866:Microsurgery / Q000295:instrumentation*; D010781:Photography; D019233:Retreatment; D012387:Root Canal Filling Materials / Q000627:therapeutic use*; D012388:Root Canal Irrigants / Q000627:therapeutic use; D018915:Root Canal Preparation / Q000295:instrumentation*; D012973:Sodium Hypochlorite / Q000627:therapeutic use; D012997:Solvents / Q000627:therapeutic use; D014464:Ultrasonic Therapy / Q000295:instrumentation*
chemical_list: D012387:Root Canal Filling Materials; D012388:Root Canal Irrigants; D012997:Solvents; D006171:Gutta-Percha; D012973:Sodium Hypochlorite